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Contents

41.1 Introduction . . . 751

41.2 Clinical Pictures . . . 752

41.2.1 Immediate-Type Reactions . . . 752

41.2.1.1 Contact Urticaria . . . 752

41.2.1.2 Protein Contact Dermatitis . . . 753

41.2.2 Irritant Contact Dermatitis . . . 754

41.2.2.1 Mechanical Irritation . . . 754

41.2.2.2 Chemical Irritation . . . 755

41.2.3 Allergic Contact Dermatitis . . . 755

41.2.3.1 Acute ACD: Acute Eczema . . . 755

41.2.3.2 Chronic ACD and the Example of “Tulip Fingers” . . . 755

41.2.3.3 Erythema Multiforme-like and Atypical Dermatitis . . . 757

41.2.3.4 Airborne Contact Dermatitis . . . 758

41.2.4 Photodermatitis (Phytophotodermatitis) . . 758 41.2.4.1 Phytophototoxicity . . . 758

41.2.4.2 Phytophotoallergic Contact Dermatitis . . . 761

41.3 Inducers of Dermatitis . . . 761

41.3.1 Alliaceae (Onion Family) . . . 761

41.3.2 Alstroemeriaceae (Alstroemer Family) and Liliaceae (Lily Family) . . . 762

41.3.3 Amaryllidaceae (Daffodil Family) . . . 764

41.3.3.1 Anacardiaceae, Ginkgoaceae, and Proteaceae 764 41.3.4 Compositae (Asteraceae) and Liverworts . . 769 41.3.4.1 Asteraceae/Compositae (Daisy Family) . . . 769

41.3.4.2 Liverworts (Jubulaceae) . . . 772

41.3.4.3 Sesquiterpene Lactone Allergens . . . 772

41.3.5 Cruciferae (Cabbage or Mustard Family, Brassicaceae) . . . 774

41.3.6 Euphorbiaceae (Spurge Family) . . . 775

41.3.7 Lichens . . . 776

41.3.8 Primulaceae (Primrose Family) . . . 778

41.3.9 Ranunculaceae (Buttercup Family) . . . 779

41.3.10 Umbelliferae/Apiaceae (Carrot Family), Rutaceae (Rue Family) and Moraceae (Mulberry Family) . . . 780

41.3.11 Woods . . . 781

41.3.11.1 American and Australian Woods . . . 782

41.3.11.2 Asian Woods . . . 783

41.3.11.3 African Woods . . . 783

41.3.11.4 European Woods . . . 784

41.3.12 Mushrooms . . . 785

41.3.13 Ferns . . . 785

41.3.14 Miscellaneous Plants . . . 785

41.1 Introduction Contact dermatitis from plants or plant products, phytodermatitis, is frequently observed in clinical practice. It is likely that the most frequent reactions of this type, which occur due to occasional and irri- tant contacts such as those encountered during lei- sure activities, are not seen by dermatologists. Practi- tioners usually see more severe dermatitis cases, with irritant or allergic mechanisms, of immediate or de- layed type, and sometimes photoworsened or even photoinduced dermatitis. Chapter 41 Plants and Plant Products Christophe J. Le Coz, Georges Ducombs 41

41.3.14.1 Araliaceae (Ginseng, Aralia, Ivy Family) . . . 785

41.3.14.2 Papaveraceae (Poppy Family) . . . 786

41.3.14.3 Guttiferae (St John’s Wort or Mangosteen Family) . . . 786

41.3.14.4 Hydrangeaceae . . . 786

41.3.14.5 Iridaceae (Iris Family) . . . 786

41.3.14.6 Solanaceae (Nightshade Family) . . . 786

41.4 Diagnosis of Plant Dermatitis . . . 787

41.4.1 Raw Plants . . . 787

41.4.1.1 Plant Identification . . . 787

41.4.1.2 Prick Tests . . . 787

41.4.1.3 Patch Tests . . . 787

41.4.2 Plant Extracts . . . 788

41.4.3 Allergen Identification . . . 788

41.4.4 Commercial Allergens . . . 788

41.4.5 Photopatch Testing . . . 788

41.4.6 Results and Relevance . . . 789

41.4.7 Multiple Plant Reactions and Cross-sensitivity . . . 790

41.5 Prevention and Treatment . . . 790

41.5.1 Removal of the Allergens and Irritants . . . . 790

41.5.2 Barrier Creams . . . 790

41.5.3 Gloves . . . 790

41.5.4 Acute Dermatitis . . . 790

41.5.5 Chronic Dermatitis . . . 790

41.5.6 Hyposensitization . . . 791

41.6 Example of Botanical Nomenclature . . . 791

References . . . 791

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The exact incidence of dermatitis from plants and plant products is not known, but this problem is not rare. Many patients likely self-medicate following self-diagnosis or diagnosis by a pharmacist, or attend their family doctor who prescribes palliative treat- ment without necessarily ascertaining the cause of the skin reaction. In other instances, cases do reach the dermatologist. For example, among 1752 patients considered to have occupational dermatitis, Fregert found that 8% of women and 6% of men were react- ing to plant-derived products [1]. We can therefore estimate that, among patients attending dermatolog- ic clinics for dermatitis, an average of 5–10% suffer from dermatitis caused by plants or plant products. It is, however, evident that geographical variations in flora considerably influence the epidemiology of plant dermatitis.

In Europe, many phytodermatitis cases are occu- pationally acquired. Florists, gardeners, horticultur- ists, foresters, woodworkers, farmers, cookers and people in contact with food preparation are at risk, as described by Paulsen [2–4]. Hobby gardeners, house- wives and those who handle or come into contact with plant materials non-occupationally are also at risk. Indeed, any persons enjoying leisure pursuits in the garden or countryside (children playing, camp- ers, walkers and so on) are likely to come into contact with plant material with the potential to cause con- tact dermatitis.

For plants and plant products, reactions of mixed aetiology are frequent, like allergic reactions super- imposed on irritant reactions due to Asteraceae, or mechanical plus chemical irritations evoked by stinging nettles. It is frequently hard to distinguish between allergic and irritant mechanisms in clinical examination and during patch test procedure, and the reader will have to bear this in mind constantly.

We will limit this chapter to plant contact, and will not consider the effect of systemic administration of plants of plant extracts.

It is clearly impossible to provide an exhaustive catalog of cutaneous side-effects of plants in this chapter (which owes much to the previous edition by Georges Ducombs and Richard J. Schmitt), and the reader will sometimes be invited to examine the question in more detail using other sources. Some books are prominent in botanical dermatology, like those written by Mitchell and Rook [5], Lovell [6], Sell [7], or Benezra, Ducombs, Sell and Foussereau [8]. Others focus on, are devoted to, or are restricted to geographical areas [9]. Many (but not all) impor- tant medical articles and reviews are indexed in international databases like the United States National Library of Medicine (see http : //www.nlm.nih.gov/).

We also warmly recommend the website BoDD (Bo-

tanical Dermatology Database, owner Richard J.

Schmitt, see http : //bodd.cf.ac.uk/index.html) for its interesting content [10].

41.2 Clinical Pictures

41.2.1 Immediate-Type Reactions

The types of reaction reviewed in this section belong to the class of immediate responses that have immu- nological or nonimmunological mechanisms.

41.2.1.1 Contact Urticaria

Contact urticaria appears within minutes following contact with the plant. It has been described for vari- ous species [11, 12].

Nonimmunological Contact Urticaria

Probably the best known urticant plants are the net- tles belonging to family Urticaceae, like Urtica dioica L., U. urens L., and U. pilulifera L. The stinging hairs are disposed on the ventral faces of the leaves, per- mitting skin penetration of histamine, acetylcholine and 5-hydroxytryptamine after only a very slight touch. Nettles are used for rheumatic disorders in folk medicine [7, 13].

Among other nonprotein substances, plant-de- rived pharmacological elicitors of urticaria are nu- merous, and include Myroxylon pereirae (balsam of Peru) and the cinnamic acid derivatives contained therein (Fig. 1), thapsigargin from Thapsia garganica L. (family Apiaceae) [11, 14, 15], and capsaicin from different species of capsicum, such as paprika and cayenne (Capsicum spp., family Solanaceae). The mechanism by which nonimmunologic urticant agents elicit their effect (at least for those agents list- ed above) appears to involve the release of histamine from mast cells.

쐽 Contact urticaria from nonprotein chemicals is most often due to a non-immunological mechanism.

Immunological (IgE-mediated) Contact Urticaria Fruits and vegetables may induce allergic contact ur- ticaria, mainly in people with previous dermatitis,

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like atopic dermatitis (see Sect. 41.2.1.2, Protein Con- tact Dermatitis). For example, sensitization from birch pollen ( Betula alba L., family Betulaceae) may be complicated by immediate symptoms occurring after ingestion (mouth swelling) or skin contact (contact urticaria) due to apples, hazelnuts, almonds, plums, apricot, peach, cherries, or celery and carrot.

This is due to strong homologies with the birch pol- len allergens Bet v 1 and/or Bet v 2.

A case report of occupational contact urticaria and type I sensitization attributable to a gerbera (probably Gerbera jamesonii Bolus, family Astera- ceae) has been reported. Conjunctivitis and respira- tory symptoms are possible [16].

Airborne contact urticaria can be associated with rhinitis, conjunctivitis or asthma. This has been largely reported as an occupational problem in health workers with hypersensitivity to latex proteins from rubber gloves made with natural latex (usually derived from Hevea brasiliensis Muell.Arg., family Euphorbiaceae). Airborne transmission of the latex allergens is enhanced by their adsorption onto the cornstarch (derived from Zea mays L., family Grami- neae) used as glove powder [17]. Airborne contact ur- ticaria reported in a warehouseman resulted from

exposure to dust derived from cinchona bark ( Cin- chona spp., family Rubiaceae) [18].

Allergic urticaria may spread from the initial site of contact, become generalized or be associated with systemic symptoms of anaphylaxis.

쐽 Immunologic-type contact urticaria is due to specific IgE synthesis, mainly to proteins, and can be severe, with generalized or systemic symptoms.

41.2.1.2 Protein Contact Dermatitis

Protein contact dermatitis is mostly seen in persons (with atopy in 50% of cases) who handle foods, meat or vegetables, and has been described with frequent foods like onion, lettuce, potato, carrot or more rare- ly with asparagus (personal observation). It general- ly consists of a chronic dermatitis, mainly located on

Fig. 1.Cinnamic acid, CAS 621–82–9, cinnamic aldehyde, CAS 104–55–2, thapsigargin, CAS 67526–95–8 and capsaicin CAS 404–86–4

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hands and forearms, with acute urticaria appearing within minutes of contact with food proteins, which rapidly disappears. It is followed by worsening of the dermatitis within hours or days [19–23]. Protein con- tact dermatitis can be of irritant (nonspecific) or al- lergic (IgE-mediated) type. In such cases, atopy with immediate-type sensitizations to pollens is frequent.

쐽 Protein contact dermatitis due to plant or plant products consists of contact urticaria followed by worsening of a previous der- matitis, mainly occurring in food handlers.

41.2.2 Irritant Contact Dermatitis 41.2.2.1 Mechanical Irritation

A number of plants can provoke “macrotraumatic”

injury by mechanical means due to their armament of prickles, spines or thorns. Others, because of the knife-like morphologies of their leaf edges, may lac- erate the skin. Although typically a trivial and self- limiting event, such mechanical damage may lead to the development of sores, secondary infections such as pyodermitis or tetanus, and granulomatous le- sions that may develop insidiously some time after the initial trauma, after it has been forgotten. In arid regions of the Americas for example, cacti (family Cactaceae) are responsible for injuries that may be- come granulomatous, after dermal embedding of plant material [24, 25] (Fig. 2).

Certain plants are injurious because their bristles or barbs (named trichomes or glochids, respectively) can cause “microtrauma.” These structures can pene- trate the outer layer of the skin and cause papular dermatitis, prurigo and even symptoms of urticaria.

In 1956, Shanon and Sagher [26] described “Sabra dermatitis,” due to occupational contact with the prickly pear, also named the Indian or Barbary fig (Opuntia ficus-indica Miller, family Cactaceae) (Fig. 3). Dermatitis is caused by penetration of gloch- ids from the spine cushions of the plants and their fruits through the skin, and it simulates chronic ecze- ma or scabies.

Microtrauma (and chemical irritant action) from calcium oxalate needle crystals (named raphides) al- so causes a characteristic dermatitis resembling that from glass fiber [27]. Irritant contact dermatitis oc- curs almost systematically in people who handle

plants that contain crystals such as blue agave ( Agave tequilana Weber) [28]. Penetration of the skin by such raphides may be accompanied by intracutane- ous injection of plant sap. This can result in an irri- tant or allergic skin reaction to one or more of the sap constituents. Thus, preparation of the tubers of various aroids (plants of Araceae family) for food use

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Fig. 2.Granulomatous lesions on a child’s arm from cactus (courtesy of F. Vakilzadeh)

Fig. 3.Indian or Barbary fig (Opuntia ficus-indica Miller, fam- ily Cactaceae)

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(for example the malanga or cocoyam, Xanthosoma sagittifolium L.) carries with it the risk of dermatitis from the calcium oxalate needle crystals and the sap- onins it contains [29]. Similarly, calcium oxalate ra- phides in dumbcanes ( Dieffenbachia spp., family Ar- aceae), which are commonly grown as decorative house plants, are responsible for an edematous urti- caria-like dermatitis, and/or an edematous and bul- lous stomatitis in people who have handled damaged plant material or accidentally chewed the leaves. The reaction in the mouth renders the victim speechless (hence the common name of the plant, dumbcanes) and may even be life-threatening if the airway be- comes obstructed. The severity of the reaction has been ascribed to the presence of a protease named dumbcain in the plant sap, which contributes to the irritant reaction [30].

쐽 Trauma due to plants may be due several mechanisms. Prickles, spines or thorns provoke macrotraumas, and leaves may act like knifes. Microtrauma may be due to dermo-epidermic penetration of trichomes (bristles), glochids (barbs), or raphides (calcium oxalate needle crystals).

41.2.2.2 Chemical Irritation

Many plants contain irritant substances (Table 1) which vary from weakly irritant compounds, requir- ing repeated exposure or a damaged skin barrier to exert their effects, to some of the most irritant com- pounds known to Man, which can elicit inflamma- tion in microgram quantities, like these contained in Euphorbiaceae. Such potent skin irritants are also mucous membrane irritants, and can cause violent purgation after ingestion, and intense ocular irrita- tion that may lead to blindness when there is contact with the eyes. The mechanical role of calcium oxalate needles has been described above: they moreover en- hance the action of toxic chemicals such as the prot- eloytic enzyme bromelain (of pineapple), or the toxic glucosides contained herein, the so-called saponins.

Acute irritant dermatitis can arise after some min- utes or hours. Chronic dermatitis develops after re- peated contact with the irritant agent or on the back- ground of previous contact with weakened skin. The clinical presentation of irritant contact dermatitis is various, but lesions are generally monomorphous in

a patient (as with burns) and are limited to sites of contact, such as the hands, forearms, mucous mem- branes, perioral regions, buttocks, and so on. They consist of simple dryness of the skin, cracking and hyperkeratosis, inflammatory reactions with edema, erythema, papules, and vesicles. Pain rather than itching is also a feature. Strong irritant plants like spurges ( Euphorbia spp., family Euphorbiaceae) may induce blisters, ulceration, or necrosis by the way of their acrid milky juice. Ranunculaceae, such as Ra- nunculus bulbosus L. or R. repens L., are sometimes used in traditional medicine, have been reported to be strong irritants, inducing bullous or even necro- tizing dermatitis by the way of ranunculin [7, 13, 31].

쐽 Chemical irritation from plants (such as Euphorbiaceae) may induce severe chemical burns.

41.2.3 Allergic Contact Dermatitis

Allergic contact dermatitis (ACD) from plants can present in many forms, depending upon both the al- lergen and the method of exposure. Typical forms are represented by acute ACD, fingertips or periungueal chronic ACD, airborne ACD, contact urticaria, and erythema multiforme-like eruptions.

41.2.3.1 Acute ACD: Acute Eczema

The normal presentation is that of a typical ACD, in- volving exposed parts such as the hands, forearms, eyelids, and sometimes the genitals if the allergen is conveyed by the hands or clothing. Lesions onset at the site of contact are frequently diffuse, spreading on unexposed areas. The initial maculopapular or ve- sicular eruption may provoke blisters or develop into a full-blown erythroderma as, for example, with Frullania (Jubulaceae family) dermatitis.

41.2.3.2 Chronic ACD and the Example of “Tulip Fingers”

A number of examples of usually occupationally ac- quired finger dermatitis have been described, with some typical features. This takes the form of finger- tip dermatitis, painful rather than pruritic, fissured

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and hyperkeratotic, of which the best-known exam- ple is “tulip fingers,” seen in tulip pickers (Tulipa spp.

and cultivars, family Liliaceae). Lesions frequently spread on periungueal sites, inducing onychosis.

Similar reactions may arise in persons handling daf- fodil and narcissus bulbs (Narcissus spp. and culti- vars, family Amaryllidaceae), Alstroemeria flowers ( Alstroemeria spp. and cultivars, family Alstroemeri-

aceae) (Fig. 4a, b), garlic ( Allium sativum L., family Alliaceae), and so on. The most frequently involved fingers are those that are in direct and prolonged contact with the bulb. For garlic dermatitis in cooks, the nondominant hand is generally involved, since it is the one used to maintain the bulb. Although nomi- nally an immunological delayed-type reaction, tulip fingers and related eruptions such as “daffodil itch”

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Table 1.Main plants responsible for chemical irritant contact dermatitis

Family Botanical name English name French name German name Offending chemicals Agavaceae Agave americana Linné. Agave Agave d’Amérique Amerikanische Calcium oxalate

Agave Sapogenins

Amaryllidaceae Narcissus pseudo- Daffodil Jonquille Gelbe Narzisse Calcium oxalate narcissus

Narcissus poeticus L. Poet’s narcissus Narcisse des poètes Dichternarzisse Calcium oxalate Araceae Dieffenbachia picta Schott Dumb cane Dieffenbachia Dieffenbachie Calcium oxalate

Philodendron spp. Philodendron Philodendron Baumlieb

Bromeliaceae Ananas cosmosus Pineapple Ananas Ananas Calcium oxalate

Bromel(a)in Brassicaceae Armoracia rusticana Horse radish Raifort Meerrettich Isothiocyanates

Brassica oleracea var. Broccoli Brocoli Brokkoli italica

Brassica nigra L. True mustard Moutarde noire Schwarzer Senf Raphanus sativus L. var. Small radish Radis Radieschen sativus

Sinapis alba L. White mustard Moutarde blanche Weisser Senf

Euphorbiaceae Euphorbia spp. Spurge Euphorbe Wolfsmilch Latex:

Euphorbia pulcherrima Poinsettia Poinsettia Weinachtsstern esters of phorbol Willdenow

Codiaeum variegatum Croton Croton Wunderstrauch esters of ingenol Hippomane mancinella Manchineel tree Mancellinier Manzanillbaum

Ricinus communis L. Castor bean Ricin Rizinus, Wunderbaum

Liliaceae Hyacinthus orientalis L. Hyacinth Jacinthe Gartenhyazinthe Calcium oxalate

Polygonaceae Rheum rhaponticum L. Rhubarb Rhubarbe Rhabarber Calcium oxalate

Ranunculaceae Anemone pavonina Lam. Anemone Anémone Anemone Protoanemonin

Ranunculus acer L. Meadow Bouton d’or Butterblume butter-cup

Aquilegia vulgaris L. Columbine Ancolie des jardins Gemeine Akelei Caltha palustris L. Yellow marsh Souci d’eau Sumpfdotterblume

marigold

Solanaceae Capsicum frutescens L. Chillies Piment de Cayenne, Cayennepfeffer Capsaici langue d’oiseau

Capsicum annuum L. Sweet pepper, Poivron, piment Tachepfeffer, capsicum doux and piment Paprika

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or “lily rash” in daffodil bulb or flower handlers [32]

may arise in part from mechanical and/or chemical irritation.

41.2.3.3 Erythema Multiforme-like and Atypical Dermatitis

Bonnevie first described an erythema multiforme- like rash that developed after contact with leaves of Primula obconica Hance (family Primulaceae) [33].

The clinical picture resembles that of a drug erup- tion, with confluent pseudo-cockades arising on the contact area. Histopathological features are those of allergic contact dermatitis with severe edema and keratinocyte necrosis. Several authors have reported similar features following contact with poison ivy [34] or tropical woods such as Rio rosewood ( Dalber- gia nigra Allemão; pao ferro, Machaerium scleroxy- lon Tul., family Leguminosae) [35–38] (Fig. 5). Fur- ther nonoccupational cases have been reported in

the literature. An occupationally acquired airborne erythema multiforme-like eruption was due to py- rethrum ( Tanacetum spp., family Compositae) used as a pesticide [39].

Fig. 4a, b.

aAlstroemeria spp. family Alstroemeriaceae. b Allergic contact dermatitis in a nur- sery gardener from Alstroe- meria (courtesy of P.J.

Frosch)

a

b

Fig. 5. Erythema-multiforme-like reaction in a carpenter caused by wood dust (pao ferro) (courtesy of P.J. Frosch)

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Erythema multiforme-like dermatitis can be the expression of an active sensitization for several days following initial contact [40].

Intense blistering can evoke pemphigoid, as was observed in the wife of a woodworker who had been helping her husband work with bois d’Olon, a kind of satinwood ( Fagara heitzii Aubrév.and Pellegrin,fam- ily Rutaceae) [41].

41.2.3.4 Airborne Contact Dermatitis Hjorth et al [42] described an airborne ACD of plant origin, due to air-conveyed oleoresins of Compositae, mimicking and often misdiagnosed as a photoder- matitis. However, some features may differentiate it from photodermatitis, since airborne contact derma- titis involves the upper eyelids, the triangle of skin behind the earlobe, the backs of facial folds without respect for the triangle under the chin (Fig. 6). Al- though pollens were usually incriminated as the causative agents of airborne phytodermatitis, it is likely that finely pulverized materials derived from dead plants are the more likely etiological agents in the case of ragweeds ( Ambrosia spp.) and related members of the Compositae family. Vaporized aller- gens may be responsible for airborne contact derma-

titis in florists exposed to chrysanthemums ( Den- dranthema cultivars, family Compositae) [43] or to Alstroemeria L. [44]. It was also noted that simply walking in a forest may bring on an attack of eczema in patients who are sensitized to liverworts of the ge- nus Frullania (Frullania dilatata Dum., family Jubu- laceae for example), suggesting that either particles of liverwort or vaporized allergens are the causative agents [45]. Other reports describe airborne contact dermatitis from lichen particles [46, 47] or pine dust (unidentified species of the family Pinaceae) [48].

The last cases exhibited positive patch test reactions to colophony.

In North America and elsewhere it is recognized that the smoke from burning poison ivy ( Toxicoden- dron spp.) and related plants in the Anacardiaceae family may sensitize if the allergenic oleoresin is va- porized rather than pyrolyzed [49]. Airborne contact dermatitis to feverfew or congress grass ( Parthenium hysterophorus L., Asteraceae family) is a major der- matological problem, particularly in northern India.

The classical form involves exposed areas, but sebor- rheic-like dermatitis, widespread dermatitis, photo- sensitive lichenoid reactions and prurigo nodularis- like eruptions have been reported [9, 50]. Patients suffer seasonal relapses but sensitivity is lifelong, and sometimes complicated by the development of pho- tosensitivity [50, 51].

41.2.4 Photodermatitis (Phytophotodermatitis) 41.2.4.1 Phytophototoxicity

Oppenheim first described dermatitis bullosa striata pratensis, or “meadow dermatitis,” in 1926 [52, 53].

The condition only develops under particular cir- cumstances. The individual, having been out in the sun for some time with areas of bare skin and having been sunbathing on damp grassy vegetation, notices the appearance, over several hours, of a pruritic ery- thematous and bullous rash in a distribution pattern mimicking the shape of the grass or the veins of leaves (Fig. 7). Damp vegetation may be replaced by atmospheric humidity or perspiration. The linear, figurate, and vesiculobullous nature of the lesions on sun-exposed skin leads one to suspect the phototox- ic nature of the dermatitis. Dermatitis generally peaks around 72 h, and healing is accompanied by postinflammatory hyperpigmentation. Currently, Oppenheim dermatitis occurs frequently after gar- dening, and the so-called strimmer rash appears to be a variant of this condition, having a diffuse rather than striated or figurate presentation; a “strimmer”

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Fig. 6. Airborne contact dermatitis from Compositae in a farmer. Note the marked infiltration on the forehead and the sharp upper border from wearing a hat (courtesy of N. Hjorth)

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(string trimmer) is an ingenious hand-held device for cutting vegetation with a mechanically whirled string (nylon filament) [54, 55]. Oppenheim derma- titis can easily be reproduced in individuals exposed to the same conditions [56], rapidly suggesting a nonallergic mechanism. Some peculiar situations have been reported, such as the epidemic of Oppen- heim dermatitis in 58 soldiers on an exercise in open country [57], or the phytophototoxicity with exten- sive linear and blistering skin lesions on the back of an 8-year-old girl that was mistaken for signs of whipping by her father [58].

Meadow dermatitis and associated conditions are commonly ascribed to contact with members of the Asteraceae/Umbelliferae plant family that grow in grassy meadows. In Europe in late summer these plants are in fact a common cause of bullous derma- titis, which may present in a wide variety of circum- stances. Such dermatitis is caused by furocoumarins (also known as furanocoumarins or psoralens) (Fig. 8), which are present in the implicated plants and cause exaggeration of the burning potential of sunlight or artificial ultraviolet light, generally UVA.

Numerous plants contain psoralens, although they have a limited distribution in the plant kingdom, the most important sources being the families Apia- ceae/Umbelliferae, Fabaceae/Leguminosae, Mora- ceae, and Rutaceae [5, 8, 59].

Coumarin derivatives such as isopimpinellin and limettin also possess photosensitizing properties, and large amounts have been isolated from citrus peels [60].

Another category of photosensitizers are the furo- quinolines, among them dictamnine, which is isolat- ed from the roots of Rutaceae such as Dictamnus al- bus L., Skimmia repens Nakai, Aegle marmelos Cor- rea, Zanthoxylum alatum Roxb., and Ruta graveolens L. [61–63] (Fig. 9). Important examples of phototoxic plants are reported in Table 2.

Phototoxic contact dermatitis may present as the so-called berloque dermatitis, induced by perfumes or perfumed cosmetics containing high amounts of psoralens, in particular oil of bergamot. Berloque dermatitis normally begins in the neck or décolleté, with erythema at the site where perfume runs down the skin and is irradiated by the sun. Again, this is normally followed by postinflammatory hyperpig- mentation, which may last months or years. This der- matitis is currently rare due to the avoidance of fra- grances containing psoralens, but it can be observed with artisan or traditional fragrances [64].

Fig. 7.Phototoxic dermatitis from furocoumarin-containing plants (courtesy of P.J. Frosch)

Fig. 8.Structures of psoralens. Psoralen (ficusin) CAS 66–97–7, 5-methoxypsoralen (bergapten) CAS 484–20–8, and 8-methoxyp- soralen (xanthotoxin or methoxalen) CAS 298–81–7

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Table 2.Main phototoxic plants

Family Botanical name English name French name German name

Apiaceae or Umbelliferae Ammi majus L. Bullwort, Bishop’s weed Ammi élevé Grosse Knorpelmöhre Angelica archangelica L. Garden angelica Angélique Engelwurz, Garten

Angelik Angelica sylvestris L. Wild angelica Angélique des Wilde Engelwurz

bois

Anthriscus sylvestris Cow Chérophylle

Hoffmann parsley sauvage, cerfeuil Wiesen-Kerbel

sauvage

Apium graveolens L. Wild celery Céleri sauvage, Echte Sellerie, Epf ache puante

Apium graveolens Celery Céleri à côtes Stielsellerie var.dulce Persoon

Daucus carrota L. Common garden carrot Carotte Karotte, Möhre ssp sativus Hayek

Foeniculum vulgare Fennel Fenouil Gemeiner Fenchel

Miller

Heracleum lanatum Cow parsnip, Grande berce Herkulesstaude,

Michaux. masterwort laineuse Bärenklau

Heracleum mantegaz- Giant hogweed, Berce du Kaukasicher zianum Somm and Lev. parsnip tree Caucase Bärenklau Heracleum sphondylium Hogweed Grance berce Wiesen-Bärenklau L.

Heracleum stevenii Palm of Tromsø – –

Manden

Pastinaca sativa L. Parsnip, madnep Panais, Pastinak,

queenweed pastenade Hammelmöhre

Petroselinum crispum Parsley Persil Petersilie

Fabaceae or Leguminosae Psoralea corylifolia L. Babchi, bakuci Psoralier Harzklee Myroxylon peirerae Balsam tree Baume du Pérou Balsam Baum Klotzsch.

Moraceae Ficus carica L. Fig tree Figuier Feigenbaum

Rutaceae Citrus aurantifolia Lime Citron vert Limone

Swingle

Citrus aurantium L. Bitter orange Bigaradier, Bittere Orange, orange amère Pomeranze, Citrus bergamia Risso Bergamot orange Bergamote Bergamottzitronen,

and Poit. Bergamotte

Citrus limetta Riss. Sweet lemon Citron doux Süsse Zitrone

Citrus limon (L.) Burm. Lemon Citron Zitrone

Citrus paradisi Macfad. Grapefruit Pamplemousse Pumpelmuss Citrus sinensis Osbeck Sweet orange Orange douce Apfelzine

Cneoridium dumosum Bushrue, berryrue – –

Dictamnus albus L. Gasplant, fraxinella, Fraxinelle, Weisser Diptam burning bush buisson ardent

Pelea anisata H. Mann Mokihana fruits Mokihana Mokihana Ruta chalepensis L. Fringed rue Rue à feuilles Aleppo-Raute

étroites, rue d’Alep

Ruta graveolens L. Rue, Herb of grace Rue fétide, rue Weinraute, des jardins Garten-Raute

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41.2.4.2 Phytophotoallergic Contact Dermatitis

Plant or plant-product-induced photoallergic der- matitis occurs only very rarely. Perhaps the only well- authenticated cases are a reaction to Parthenium hys- terophorus L. (family Asteraceae) [65] and a photoal- lergy to psoralens [66]. However, experimentally in- duced photoallergies to psoralens and to other cou- marins known to occur naturally have been de- scribed [67]. It is difficult to differentiate between a photoworsened allergic contact dermatitis and a true photoallergy. Photoworsening of an allergic contact dermatitis is the more likely diagnosis than true pho- toallergy when plant material is implicated as the cause of a photosensitivity reaction of the skin [46, 47] in lichen pickers with a history of photosensitiv- ity.

A rather different relationship between contact al- lergy and photosensitivity is seen in chronic actinic dermatitis (persistent light reaction, photosensitive eczema, or actinic reticuloid). In such patients, gen- erally men over 50 years, dermatitis occurs in photo- exposed areas during the sunny season, which then worsens with a chronic course, including itching, li- chenified, and extensive lesions or even erythroder- ma. Patients have a marked broad spectrum photo- sensitivity to UVB, UVA or even visible radiations. It is frequent to observe contact sensitivity (but not photoallergic reactions) to oleoresins from members of the plant family Asteraceae and sesquiterpene lac- tones contained herein, or photosensitivity to photo- allergens such as musk ambrette or sunscreens, but the disease expresses itself even in the absence of ex- posure to the plant material. It appears that an initial contact sensitization progresses to a generalized photosensitivity state with a relationship between plants of the family Compositae, the sesquiterpene lactones they contain, and chronic actinic dermatitis [68–71].

41.3 Inducers of Dermatitis

It is not possible to consider the whole panorama of plants liable to elicit contact dermatitis here, but the plants most often incriminated are described below.

Occupational contacts [12, 72] are usually the most frequent inducers of plant contact dermatitis.

41.3.1 Alliaceae (Onion Family)

Members of the family Alliaceae are widely grown and used for culinary purposes. In addition, garlic ( Allium sativum L.) has both a contemporary and a folkloric history of use as a medicinal agent. Whilst the lachrymatory properties of onions ( Allium cepa L.) are widely appreciated, they are rarely discussed in the medical literature. Most commonly reported is occupational dermatitis from garlic and to a lesser extent from onion; this includes both immediate and delayed reactions [19, 73–78]. A typical presentation is a circumscribed irritable hyperkeratotic eczema on the fingers of one or both hands; sometimes the thumb, index and middle fingers of the nondominant (usually left) hand which may be used to grasp the garlic bulb whilst the knife is held in the right hand [79]. Less distinct patterns of eczema are likely more frequent than the presentation described above, but remarkable situations can occur, such as haemor- rhagic and blistering contact dermatitis [80], cheiro- pompholyx associated with the ingestion of garlic extract [81], dermatitis of the elbow flexures, lower back and periorbital regions with cheilitis [82], or airborne dermatitis due to garlic powder, which was also reported as a cause of immediate-type reactions such as conjunctivitis, rhinitis and asthma [83].

Garlic and other Allium species have often been reported to have both irritant and allergenic proper- ties, due to phytochemicals not present in undam- aged plant material, but released as a response to damage. They are derived from a variety of sulfur- containing amino acids present in the intact plants. A

Fig. 9.Structures of limettin CAS 487–06–9, isopimpinellin CAS 482–27–9, and dictamnine, CAS 482–27–9

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minor structural difference between the principal precursor compounds, namely S-(1-propenyl)-

L

-cys- teine sulfoxide and S-(2-propenyl)-

L

-cysteine sulfox- ide or alliin for garlic, results in an enzymatic trans- formation by the thermolabile alliinase: the lachry- matory thiopropanal- S-oxide from onion, but allicin and diallyldisulfide from garlic, as illustrated in Fig. 10 [84]. Diallyldisulfide, allylpropyldisulfide, and allicin have been identified as the principal low mo- lecular weight allergens of garlic [85]. Commercial diallyldisulfide seems to be a suitable preparation for the investigation of garlic dermatitis, although 1%

pet. may carry a lower risk of irritancy or can be neg- ative. Irritant reactions with plants are expected with fresh garlic concentrations higher than 10% but con- centrations up to 50% for garlic and onion in arach- nid oil were considered to be safe [78]. It is likely that each different extraction procedure affects the man- ner in which the irritants/allergens are released, making it virtually impossible to produce a standard extract. So, patch tests with plant extracts or plant material used as is must be interpreted with some caution [86]. Delayed-type cross-reactions between garlic and onion, although occasionally described, are unlikely.

41.3.2 Alstroemeriaceae (Alstroemer Family) and Liliaceae (Lily Family) These two families are considered together because members of the genera Alstroemeria L.(Peruvian lily, Inca lily) and Bomarea Mirb. (family Alstroemeria- ceae), and the genus Tulipa L. (family Liliaceae) pro- duce the same allergen, tulipalin A (Fig. 11). The sub- stance is released when the plant material (flowers, stems and leaves) is damaged [87–90]. Tulipalin A, otherwise known as α-methylene-γ-butyrolactone,is

obtained from a glucoside precursor known as tulip- oside A. This one can be present as 1-tuliposide A [91]

or more frequently identified as 6-tuliposide A [92–94].

Tulips contain a second glucoside, 6-tuliposide B [89], which is classically considered to be a nonsensi- tizer and has antibiotic properties, protecting the plant against bacteria [95]. Patients sensitive to tulips reportedly do not react to either tuliposide B or tu- lipalin B. However, it was demonstrated that tulipalin B ( β-hydroxy-α-methylene-γ-butyrolactone) is a sensitizer in guinea pigs, and that cross-reactivity between tulipalins A and B does occur [96]. Other tu- liposides have been detected in Alstroemeria species, for example tuliposide D [94]. There is evidence that the tuliposides themselves can elicit allergic contact dermatitis [88, 92], but this may be the outcome of some spontaneous degradation to tulipalin A on the skin [97].

Garden tulips are available both as “species tulips”

and as cultivars of hybrid origin. Dermatitis among bulb handlers and florists is a frequent but unpleas- ant occupational hazard. Bulb collectors, sorters and packers develop a characteristic dermatitis called

“tulip fingers,” a painful dry fissured hyperkeratotic eczema, at first underneath the true margin of the nails, spreading to the periungueal regions, fingers and hands [98]. Sometimes the dermatitis spreads to the face, forearms, and genital region. It seems cer- tain that both irritant and allergic contact dermatitis occurs.“Tulip fingers” is common in the Netherlands and other parts of Europe. The allergen is found mainly in the epidermis of the bulb, but dermatitis may also occur in those who handle the cut flowers [99].

Alstroemeria hybrids have been popular in the cut-flower trade since the 1980s due to their long last- ing and colored flowers (Fig. 4a, b). Horticulturists

41

Fig. 10.

Structures of thipropanal S-oxide CAS 32157–29–2, allicin CAS 539–86–6, diallyl disulfide CAS 2179–57–9, and allypropyl disulfide CAS 2179–59–1

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and florists are at high risk of both irritant and aller- gic contact dermatitis, and the rate of sensitization for tulipalin A can exceed 50% in workers of Alstroe- meria cultivation [100]. Handling of cut flowers pro- vokes a dermatitis affecting mainly the fingertips, which is similar to “tulip fingers” [101–103]. Depig- mentation may follow the resolution of Alstroemeria dermatitis or a positive patch test to plant [104]. Con- tact urticaria and rhinoconjunctivitis, with positive prick tests, were described for Alstroemeria [105].

In the preparation of plant material for patch test- ing, it should be remembered that the various culti- vars of Alstroemeria and Tulipa do not necessarily contain similar levels of tuliposide A or associated contact allergens. For example, the cultivar Rose Copeland is a notorious sensitizer [106], whereas Tu- lipa fosteriana Hoog cv Red Emperor has been found to contain very much less tuliposide than other culti- vars [98]. Nonsystematic concomitant patch test re- actions between tulips and Alstroemeria [101, 104]

may be due to differences in amount of allergens. Dif- ferent ways of performing patch testing have been

recommended, since the so-called short ether ex- tracts of Alstroemeria are too rich in tulipalin A and carry the risk of active sensitization [91]: a filtered 96% ethanol extract of the reference bulb of Tulipa cv Apeldoorn or an 80% acetone extract of the bulbs diluted with 70% ethanol immediately prior to use [98], a tuliposide-rich methanolic extract incorpo- rated into petrolatum [91], a 50- µl application of 6- tuliposide A at 0.01% or an α-methylene-γ-butyro- lactone at 0.001% in ethanol [92]. Currently, the 0.01% concentration in petrolatum seems to be effec- tive and safe for detecting sensitive people [91, 107].

쐽 Tulipalin A ( α-methylene-γ-butyrolactone) is the main contact allergen in Alstroeme- ria and Tulipa species. It frequently induces a fingertip allergy known as “tulip fingers,”

mostly in people who have occupational contact with flowers and bulbs.

Fig. 11.Structures of 1- and 6-tuliposides A (glycosidic precur- sors of tulipalin A) CAS 19870–30–5 and CAS 19870–31–6 re- spectively, tulipalin A (α-methylene-γ-butyrolactone) CAS

547–65–9 and tulipalin B (β-hydroxy-α-methylene-γ-butyro- lactone) CAS 38965–80–9

Core Message

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Common hyacinth ( Hyacinthus orientalis L.) have been described above as inducers of irritant contact dermatitis, due to calcium oxalate present in their bulbs. It is noteworthy that bulbs evoke pruritus in almost all workers who manipulate them, but derma- titis is less frequent [108]. We observed an unusual exposure in two schoolteachers who decided to de- scribe the structure of bulbs and explained in detail the way to cultivate hyacinth bulbs to their pupils (personal observations). Hyacinths likely contain as- yet unidentified allergens [106].

41.3.3 Amaryllidaceae (Daffodil Family) The Amaryllidaceae family comprises some 1100 spe- cies of plant in 85 genera, many of which are cultivat- ed for their showy flowers. Amongst these, daffodils ( Narcissus spp. and cultivars) are the most common, this term indicating several species such as trumpet narcissi ( Narcissus pseudo-narcissus L.), narcissi (other species, e.g., N. poeticus) and jonquils (Narcis- sus jonquilla L.), which constitute a significant der- matological hazard because of their irritant and al- lergenic properties. An important bulb and cut flow- er industry exists in the Netherlands and the Isles of Scilly in the United Kingdom, and with it the occupa- tional disease known as “daffodil itch” or “lily rash”

[98, 106], sometimes clinically close to “tulip fingers.”

The rash has long been ascribed in part to the cal- cium oxalate needle crystals present in both the dry outer scales of the bulbs and in the sap exuding from cut flower stems [98]. Observation in the field related the method of picking and then gathering the flowers to the development of the daffodil pickers’ rash, at the points of contact of plant sap with the skin like the finger webs, the dorsum of the hand and the anterior aspect of the wrist [109]. Dermatitis may involve the

neck, face, and the genitals [8]. It is likely that the “lily rash” is mainly caused by an irritant mechanism [108], but that an allergic reaction is possible [110].

Among many irritant alkaloids, two allergenic ones were identified from N. pseudonarcissus L., namely masonin and homolycorine (Fig. 12) [32]. Patch tests may be performed with leaves, stems and flowers, or with ethanol, acetone or water [8].

41.3.3.1 Anacardiaceae, Ginkgoaceae, and Proteaceae

These plant families are considered together because they contain similar contact allergens and hence cause similar dermatitis. Nevertheless, the clinical picture may vary depending upon the precise mode of contact.

Anacardiaceae (Cashew Family)

The Anacardiaceae family includes 60 genera com- prising some 600 species of trees and shrubs, distrib- uted throughout the tropics, and also found in warm temperate regions of Europe, eastern Asia, and the Americas. They are considered to cause more derma- titis than all other plant families combined [5]. Some tropical species are of economic importance, such as Mangifera indica L., which provides mango fruits, Anacardium occidentale L., which yields cashew nuts, cashew nut shell oil, which is used in the manu- facture of brake linings, Semecarpus anacardium L.f., which is known as the Indian marking nut tree that provides black juice used as an indelible ink when la- beling clothing, the Japanese lacquer tree Toxicoden- dron vernicifluum F. Barkley, or several other species used for dying or tanning. The main dermatological- ly important plants are reported in Table 3.

41

Fig. 12.Structures of masonin CAS 568–40–1 and homolycorine, CAS 477–20–3

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Table 3.Dermatologically important Anacardiaceae plants

Botanical name Synonyms English name French name German name

Anacardium occidentale L. Cashew nut tree Anacardier, Kaschu, Elefantenlaus noix de cajou, Baum, westindischer pomme cajou Nierenbaum Comocladia dodonaea Comocladia ilicifolia Christmas bush, Bois de houx

Urban Sw.,Ilex dodonaea L. poison ash

Gluta laccifera Ding Hou Melanorrhoea laccifera Camboge lacquer Arbre à laque

Pierre du Cambodge

Gluta renghas L. East coast rengas,

ape-nut

Gluta usitata Ding Hou Melanorrhoea usitata Burmese lacquer tree, Arbre à laque

Wallich. theetsee de Birmanie

Holigarna ferruginea March.

Lithraea caustica Hook. Lithraea venenosa Litre, aroeira

and Arn. Miers.

Mangifera indica L. Mango tree Manguier Mangobaum

Metopium toxiferum Rhus metopium L. Poisonwood, coral

Krug and Urban sumac, Florida poison

tree, Honduras walnut

Semecarpus anacardium L. Anacardium orientale Indian marking nut Anacarde Tintenbaum

Auct. tree, bhilawa tree d’Orient

Smodingium argutum African poison ivy, Smodingie, Afrikanischer Giftefeu

E. Mey. um-tovane, tovana, lierre toxique

rainbow leaf d’Afrique

Toxicodendron Rhus diversiloba Torr. Western poison oak, Sumac irrégu- Sumach, verschieden- diversilobum Greene & Gray.R. toxicoden- Pacific poison oak lièrement lobé, lappiger Sumach

dron L. ssp. diversiloba sumac de l’ouest

Engl.

Toxicodendron radicans L. Rhus villosum Sessé & Western poison oak ssp.barkleyi Gillis Moçiño

Toxicodendron radicans L. T. divaricatum Greene, Western poison oak ssp.divaricatum Gillis Rhus divaricata Greene

Toxicodendron radicans L. T. eximium Greene, Western poison oak ssp.eximium Gillis Rhus eximia Stanley

Toxicodendron radicans L. Rhus toxicodendron L. Taiwan tsuta-urushi ssp.hispidum Gillis var. hispida Engl.,

R. intermedia Hayata

Toxicodendron radicans L. T. negundo Greene, Taiwan tsuta-urushi Herbe à puce

ssp.negundo Gillis T. arborigunum Greene grimpante

Toxicodendron radicans L. T. orientale Greene, Tsuta-urushi ssp.orientale Gillis Rhus orientalis

Schneider

Toxicodendron radicans L. R. toxicodendron L. var. Tsuta-urushi ssp.pubens Gillis pubens Engelm.

Toxicodendron radicans L. T. radicans Kuntze, Poison ivy, three-leaved Sumac radicant, Sumach, Kletter-Gift- ssp.radicans Gillis Rhus radicans L., ivy, eastern poison ivy, lierre toxique, sumach, Rankender

Rhus toxicodendron L. poison vine, black vine, herbe à puce Sumach, Giftefeu

markweed de l’est

T. radicans L. ssp. T. verrucosum Greene, Poison ivy, three-leaved verrucosum Gillis Rhus verrucosa Scheele ivy, poison vine, black

vine, markweed

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Although these and many other species in the family Anacardiaceae are dermatologically hazard- ous [111–120], perhaps the most important genus is Toxicodendron. This genus includes the poison ivy complex ( Toxicodendron radicans Kuntze and sub- species such as T. radicans Kuntze var. rydbergii Ers- kine), the poison oak complex with Toxicodendron diversilobum Greene (in western North America) and Toxicodendron toxicarium Gillis (in eastern North America), and the poison sumac ( Toxicoden- dron striatum Kuntze, T. vernix Kuntze) of North America and elsewhere [121–125]. Over half of the population of the United States is sensitive to poison ivy and its relatives [126] while, because the plants are not a part of the natural flora, poison ivy dermatitis is generally unknown in Europe [127]. Clinical as- pects vary with exposure. Dermatitis initially ap- pears on the fingers, forearms, arms, legs, and some- times genitalia [8, 126]. Lesions consist of papules, vesicles, and/or blisters. Erythema multiforme-like eruption is sometimes observed. Systemic contact dermatitis may occur after accidental, medicinal or alimentary ingestion of plant materials. It may present as eczema, as a generalized maculopapular eruption or as erythroderma occurring generally within 48 h following administration. When general- ized rash occurs, leukocytosis and neutrophilia are frequent, and liver dysfunction is possible [128, 129].

The same features with eczematous eruption of flex-

ural regions, mouth, and anal itching may occur after ingestion of cashew nuts in people previously sensi- tized to poison ivy [130]. The “black spot poison ivy dermatitis” is a rarer condition, consisting of black enamel spots, due to colored and dried plant sap, sec- ondarily surrounding patch dermatitis, mainly of al- lergic origin [131].

Early literature refers to poison ivy and its rela- tives as species of Rhus. On the basis of morphologi- cal grounds and phytochemical distinction, it ap- pears that Toxicodendron is more suited, and that the genus Rhus must be distinguished from the genus Toxicodendron [10, 132], although other authors argue for using the term Rhus [7]. There is conse- quently a frequent nomenclatural confusion in the dermatological literature, especially with the numer- ous synonyms. Individual subspecies of Toxicoden- dron rarely appear in the dermatological literature, largely because case reports of poison ivy dermatitis hardly warrant publication, partly because of the dif- ficulty in precisely identifying the subspecies of the plants. The distributions of the various Toxicoden- dron species and subspecies have been described for the United States [132–134]. The “black spot test” con- sists of carefully crushing sap from the leaves of the plant onto white paper: the test is positive with Toxi- codendron, the stain darkening on exposure to the air [135]. The same phenomenon occurs with wood sap (Fig. 13). Poison ivy, poison oak, and poison sumac

41

Table 3.Continued

Botanical name Synonyms English name French name German name

Toxicodendron rydbergii T. radicans Kuntze var. Rydberg’s poison ivy, Herbe à puce Greene poison ivy rydbergii Erskine, Rhus western poison ivy de Rydberg

rydbergii Small, R. toxi- codendron L. var. ryd- bergii Garnett

Toxicodendron striatum Rhus striata Ruiz and Manzanillo, hinchador

Kuntze Pavón,R. juglandifolia

Willd.

Toxicodendron Rhus succedanea L. Japanese wax tree succedaneum Kuntze

Toxicodendron T. quercifolium Greene, Eastern poison oak, Sumac véné- Echter Gifstsumac toxicarium Gillis T. toxicodendron L. oak leaf ivy neux à feuilles

Britten,Rhus querci- de chêne

folia Steudel, R. toxico- dendron L. var. querci- folium Michx., R. toxi- carium Salisb.

Toxicodendron vernici- Rhus verniciflua Stokes, Japanese lacquer tree, Sumac à laque, Lacksumach fluum F. Barkley R. vernicifera DC. varnish tree vernis vrai

Toxicodendron vernix Rhus vernix L., Poison sumac, poison Sumac à vernis, Giftsumach

Kuntze R. venenata DC. dogwood, swamp bois chandelle

sumac, poison elder

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are native to North America but can be exported. The dermatitis can present after an individual has been in contact with the plant whilst visiting an endemic ar- ea. As the plant has the potential to grow in Europe too (Fig. 14a), it is possible for an individual to be sensitized and subsequently to develop the rash without leaving their country [136], particularly in the case of workers at botanical gardens (personal observations).

Cross-reactivity between Anacardiaceae has been reported for a long time. Similarities between uru- shiols from poison ivy and cashew nut shell oil are well known. In South America, species of Lithraea, and especially L. caustica Hook. and Arn. [10], are a frequent cause of a poison ivy-like dermatitis. In 17 Lithraea-sensitized subjects, reactions to poison oak urushiol were constant, and reactions to extracts pre- pared from Lithraea molleoides Engl. and Lithraea brasiliensis Marchand occurred in 13/17. The respons- es to poison oak urushiol were stronger and occurred at lower concentrations than those to Lithraea extracts [137]. Similar studies of cross-reactivity between Lithraea and other members of the Anacar- diaceae were reported [138, 139]. Concomitant reac- tions have been observed, but without systematic cross-reactivity, as in a patient sensitized to poison ivy or poison oak ( Toxicodendron spp.) whilst in the United States and who subsequently showed appar- ent cross-reactions to Rhus copallina L., R. semialata Murray (syn. R. javanica L.), and R. trichocarpa Miq.

[127].

Ginkgoaceae (Maidenhair Family)

Ginkgo biloba L.,the ginkgo tree,is the solitary repre- sentative of the family Ginkgoaceae and is regarded as one of the world’s oldest surviving tree species.

Contact dermatitis from the ginkgo tree is not due to its leaves but to its malodorous fruits [140], in fact to the ovules exclusively borne by female trees (Fig. 14b). Contact occurs through inadvertent con- tamination of the skin with the fruit pulp [141], col- lecting and using the nut within the fruit in an Asian cooking style [141, 142], or in children through play- ing marbles with the fallen fruits. The lesions consist of erythematous papules and vesicles, with severe swelling in severe cases. They usually affect the face, the forearms and the thighs, and sometimes the gen- italia [142, 143]. Stomatitis, cheilitis, and proctitis fol- lowing ingestion of ginkgo fruit were described [144].

Cross-reactions between ginkgo fruit pulp, poison ivy, or ginkgo and cashew nut have been discussed [145]. They were, however, not supported by a recent study of the ginkgolic acids found in Ginkgo fruits

Fig. 13.Stain darkening of sap ofToxicodendron species is the basis of the “black spot test”, here demonstrated with sap of here demonstrated with sap of a recently cut down Japanese lacquer tree (Toxicodendron vernicifluum F. Barkley)

Fig. 14a, b. a Toxicodendron radicans growing in the botanical garden of Strasbourg, France.bFemale Ginkgo tree (Ginkgo biloba L.) bearing ovules (Jardin botanique, Strasbourg, France)

a

b

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and urushiol from Toxicodendron [146]. Patch testing can be performed with fruit pulp in 1% acetone [144].

Proteaceae

The Proteaceae family comprises 1050 species in 62 genera found in tropical areas. In Australia, members of the family Proteaceae are the cause of a poison ivy- like dermatitis. The best known are probably the so- called silky oak or silver oak (Grevillea robusta Cunn.) and related Grevillea species and cultivars.

Contact with the wild and cultivated tree [147–149], as well as with objects made from the wood [150], have been recorded as being allergenic. “Grevillea poisoning” was described as a severe contact derma- titis on exposed areas in people cutting trees or maintaining electric power lines in the Los Angeles area [151]. Allergic dermatitis following contact with

flowers of Kahili or Bank’s Grevillea ( Grevillea bank- sii R. Br.) was described in Hawaii [152].

Allergens

The allergenic agents in all these members of the An- acardiaceae, Ginkgoaceae and Proteaceae are deriva- tives of catechol, phenol, resorcinol or salicylic acid with a side chain (-R) (Fig. 15). This side chain is mostly a C

15

(sometimes a C

17

) alkyl (saturated) or alkenyl (one, two or three double bonds C=C) chain [4, 8]. The alk(en)yl catechols are also known as uru- shiol, a generic name that in fact refers to the blend of several close molecules (urushiols) naturally con- tained in the plant. An urushiol with a C

15

side chain is named pentadecylcatechol (a term sometimes em- ployed in medical literature for poison ivy urushiol), and an urushiol with a C

17

side chain is a heptadecyl-

41

Fig. 15.Structures of urushiol and related allergens from Anacardiaceae (T. radicans Kuntze, A. occidentale L.), Proteaceae (G. ro- busta L.), and Ginkgoaceae (G. biloba L.) families

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catechol (mostly encountered in poison oak uru- shiol). Phenol, resorcinol, and salicylic acid com- pounds substituted with an alk(en)yl chain have tra- ditionally been called cardanol, grevillol and gink- golic acid, respectively. Because the allergenic natural plant material is a mixture of closely related com- pounds, and because of the close similarity between individual compounds from a variety of botanical sources, there is the possibility of cross-sensitization between different species throughout the world [153].

The risk of cross-sensitization extends to families other than those described in this section. The genus Philodendron (family Araceae) yields sensitizing al- kyl resorcinols [154]. The genera Phacelia and Wi- gandia belonging to the Hydrophyllaceae family yield alkenyl hydroquinones. Prenylated quinones and prenylated phenols were identified in W. caraca- sana Kunth [155], and geranylhydroquinone in P. cre- nulata Torrey (Fig. 16); this molecule does not cross- react with poison oak or ivy [156].

쐽 Plants of the family Anacardiaceae are frequent cause of contact dermatitis.

The skin reaction occurs following sensiti- zation to various alkyl or alkenyl catechols (urushiol), phenols, resorcinols or salicylic acid derivatives. These compounds are also primary irritants.

41.3.4 Compositae (Asteraceae) and Liverworts

The two families are considered together because they contain sesquiterpene lactones as allergens.

41.3.4.1 Asteraceae/Compositae (Daisy Family)

The family Asteraceae/Compositae comprises some 13,000 to 20,000 species in over 900 genera. Repre- sentatives are found throughout the world, and ex- amples may be found living in almost every situa- tion, the majority being herbaceous plants. The fam- ily provides a number of food plants, for example let- tuce, endive, chicory, dandelion, salsify, scorzonera, and artichoke. Many more are grown for their deco- rative flowers, such as chrysanthemums, dahlias, and heleniums. Others are widespread and common weeds [157]. Additionally, some species such as arni- ca, chamomile or feverfew are used medicinally, by skin application or systemic administration. It is therefore difficult to avoid contact with these plants.

Plants of dermatological interest are indicated in Table 4.

Allergic contact dermatitis from Asteraceae has several clinical presentations (Fig. 6). Accidentally exposed subjects can develop an acute and single epi- sode of dermatitis. Chronic exposure, of occupation- al origin for example, can induce acute dermatitis that can often relapse, or a primary chronic and sec- ondarily lichenified dermatitis. When the lesions are localized to the elbow or knee flexures, they can sim- ulate atopic dermatitis. The eczema, which may be lo- calized initially on the face, hands, and genitals, can become generalized as an erythroderma and can even be, in rare instances, fatal [158].

Exposure to the sesquiterpene lactones by the way of airborne plant material produces an airborne con- tact dermatitis (sometimes mistaken for a photoder- matitis). In the United States, this is known as “rag- weed dermatitis” because it is largely caused by rag- weeds, which are species of Ambrosia [159, 160] or

“weed dermatitis” in regions where other composite weeds predominate [161], such as Ambrosia, Artemi- sia, Helenium, and Iva [162–171] species. For example, cases of severe airborne ACD from triangle-leaf bur- sage ( Ambrosia deltoidea) were reported in the USA, with positive reactions to ether extracts of the plant [172].

In Australia, the same condition is described as

“bush dermatitis” due to species such as Arctotheca, Cassinia, Conyza, Cynara, and Dittrichia [167, 173–176]. In India, another variant has been called

“parthenium dermatitis” [9, 177, 178] after the offend- ing plant ( Parthenium hysterophorus L.).

The environmental conditions favoring ragweed dermatitis and its variants in hot and arid climates are not normally encountered in the temperate re- gions of Europe. Nevertheless, there are also Europe-

Fig. 16.Structure of geranylhydroquinone CAS 10457–66–6, from Phacelia crenulata Torrey

Core Message

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41

Table 4.Dermatologically important Apiaceae/Umbelliferae plants Asteraceae/Compositae

Correct name Synonyms English name French name German name

Achillea millefolium L. Achillea lanulosa Nuttall Yarrow, nosebleed, Achilée mille- Gemeine Schafgarbe milfoil, thousand leaf feuille, herbe à

la coupure

Ambrosia acanthicarpa Franseria acanthicarpa Bur-ragweed, sandbur Franserie Falsche Ambrosie

Hook. Cov. lampourde

Ambrosia artemisiifolia Ambrosia elatior L. Short ragweed, Ambroisie à Beifussblättrige Am-

L. common ragweed feuille d’armoise, brosie, hohes Tauben-

ambroisie élevée kraut, Wermutblätt- rige Ambrosie

Ambrosia psilostachya Western ragweed, Herbe à poux Ausdauernde

DeCambolle perennial ragweed, vivace Ambrosie

common ragweed

Ambrosia trifida L. Ambrosia aptera DC. Giant ragweed, Dreispaltige Ambrosie tall ragweed

Anthemis arvensis L. Field chamomile, corn Fausse camomile, Acker Hundskamille

ssp. arvensis chamomile (scentless) camomille

sauvage, anthémis des champs

Anthemis cotula L. Maruta cotula DC. Stinking chamomile, Anthémis cotule, Stinkende corn chamomile anthémis fétide Hundskamille (scented)

Arctotheca calendula Arctotis calendulacea L., Capeweed Artothèque souci Dune Calendula

Levyns Cryptostemma calendu-

lacea R. Br.

Arnica montana L. Arnica, mountain Arnica, tabac des Berg-Wohlverleih,

tobacco, wolf ’s bane Vosges, quinqui- Arnika na des pauvres

Artemisia ludoviciana Artemisia ludoviciana Dark-leafed mugwort, Armoise argentée Edelraute

Nutt. Nutt., prairie sage

Artemisia purshiana

Artemisia vulgaris L. Common mugwort Armoise vulgaire, Gewöhnlicher Beifuss, herbe aux cent Fliegenkraut goûts

Cassinia aculeata R. Br. Common cassinia,

dogwood, cauliflower bush

Chamaemelum nobile Anthemis nobilis L. Roman chamomile, Camomille Römische Kamille

All. dog fennel romaine

Cichorium endivia L. Common endive Endive, chicorée Winter Endivie

spp.endivia L. des jardins

Cichorium intybus L. Chicory, wild chicory Chicorée sauvage, Wilde Zichorie, barbe de capucin gemeine Wegwarte,

Sonnenwedel

Conyza bonariensis Erigeron bonariensis L. Fleabane Érigéron crépu Südamerikanisches

Cronq. Conyza ambigua DC., Berufskraut

Conyza crispa Rupr.

Cynara cardunculus L. Cynara cardunculus L. Cardoon Cardon, carde Kardone, Gemüse-

ssp.cardunculus; Cynara Artischocke

cardunculus L. ssp.

flavescens

Cynara scolymus L. Cynara cardunculus L. Globe artichoke Artichaut Artischoke,

ssp.scolymus; Cynara Alcachofra

cardunculus L. ssp.

flavescens

Dahlia variabilis Desf. Dahlia x hortensis Dahlia Dahlia Dahlia

Dendranthema Chrysanthemum x Autumn flowering Chrysanthème Chrysanthemen, hortorum W. Miller, chrysanthemum de Chine, Allerseelen-Aster

Chrysanthemum mori- chrysanthème

folium Ramat. d’automne

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Table 4.Continued

Correct name Synonyms English name French name German name

Dittrichia graveolens Inula graveolens Desf, Stinkwort Inule fétide Duftender Alant Greuter Erigeron graveolens L.

Gaillardia pulchella Gaillardia picta Sweet Showy gaillardia Gaillarde Kurzlebige

Foug. Foug. pulchella Kokardenblume

Helenium autumnale L. Sneezeweed, Hélénie Sonnenbrot

swamp sunflower, automnale false sunflower

Helenium amarum Helenium tenuifolium Sneezeweed, – –

H. Rock Nutt.,Gaillardia amara bitterweed Raf.

Helianthus annuus L. Sunflower Tournesol, soleil Einjährige Sonnen-

blume

Inula helenium L. Elecampane, Aunée officinale, Echter Alant, Muxiang

horseheal, scabwort grande aunée, inule aulnée

Iva angustifolia Nutt. Narrow-leaf

marshelder

Iva xanthifolia Nutt. Marshelder

Lactuca sativa L. Lettuce Laitue Lattich

Leucanthemum vulgare Tanacetum leucanthemum Marguerite, ox-eye Marguerite Gemeine Wucher-

Lam. Schultz-Bip,Chrysan- daisy blume, Wissen-

themum leucanthemum L. Margerite

Matricaria chamomilla Matricaria chamomilla German chamomile, Matricaire, Echte Kamille, L. var recutita Grieson L.,Matricaria recutita wild chamomile camomille deutsche Kamille

L.,Chamomilla recutita allemande

Rauschert

Parthenium argentatum Guayule Guayule Guayule

A. Gray

Parthenium hystero- Congress grass, Absinthe bâtard Parthenium

phorus L. Santa Maria, whitetop hysterophorus

Petasites albus Gaertner White butterbur Pétasite blanc Weisse Pestwurz Saussurea lappa C.B. Saussurea costus Lipsch. Costus Costus Costus Clarke

Silybum marianum Blessed milk-thistle, Chardon de Mariendistel

Gaertn. holy thistle Marie

Tagetes minuta L. Tagetes glandulifera Small-flowered Tagète des Tagetes

Schrank marigold, stinking décombres

roger

Tanacetum cinerariifo- Chrysanthemum cinera- Pyrethrum, Pyrèthre Dalmatinische

lium Schultz-Bip. riifolium Vis., Pyrethrum Dalmatian Insektenblume

cinerariifolium Trevir. pyrethrum

Tanacetum parthenium Chrysanthemum parthe- Feverfew Grande Mutterkraut,

Schultz-Bip. nium Bernh., Matricaria camomille Falsche Kamille

parthenium L.

Tanacetum vulgare L. Chrysanthemum tanace- Tansy, bitter buttons Tanaisie, tanacée, Gemeiner Rainfarn,

tum Karsch., C. vulgare herbe aux vers Wurmkraut

Bernh.

Taraxacum officinale Leontodon taraxacum Dandelion, blowball Pissenlit, laitue Gebräulicher Löwen-

Weber L.,Taraxacum dens- de chien, dent zahn, Kuhlblume

leonis Desf., T. taraxa- de lion

cum Karst

Xanthium spinosum L. Spiny cocklebur Lampourde Dornige Spitzklette

épineuse, petite bardane

Xanthium strumarium L. Noogoora burr Lampourde ordi- Gemeine Spitzklette, naire, herbe aux Kropfspitzklette écrouelles

X. italicum Moretti X. californicum Greene, Californian burr Lampourde Italienische

Xanthium strumarium d’Italie Spitzklette

L. ssp italicum D. Löve

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