III.13 Miescher Nevus

III.13.1 Definition

Miescher nevus is an acquired dermal melano- cytic nevus with a smooth, dome shape. This benign nevus is commonly located on the face.

III.13.2 Clinical Features

Miescher nevus is named after Guido Miescher [1, 2], who studied 100 melanocytic nevi and classified “nevus cells” into A, B, and C types according to their location within the dermis and their cytological appearance. More than half of the studied nevi were facial, endophytic, dermal lesions.

Clinically, this benign intradermal nevus presents as a dome-shaped papule with light brown or skin color. Most Miescher nevi are

Chapter III.13

Miescher Nevus

Steven Q. Wang, Harold H. Rabinovitz, Alfred W. Kopf

III.13

Contents

III.13.1 Definition . . . .139

III.13.2 Clinical Features . . . .139

III.13.3 Dermoscopic Criteria . . . .139

III.13.4 Relevant Clinical Differential Diagnoses . . . .139

III.13.5 Histopathology . . . .140

III.13.6 Management . . . .140

III.13.7 Case Studies . . . .140

III.13.7.1 Case 1 . . . .140

III.13.7.2 Case 2 . . . .140

References . . . 141

found on the face and neck. Typically, Miescher nevi are seen in people over the age of 30 years.

Today, most of the dermatology and derma- topathology textbooks simply refer to them as acquired intradermal nevi. The distinctions be- tween this acquired dermal nevus and other in- tradermal nevus, such as the Unna nevus, are no longer emphasized.

III.13.3 Dermoscopic Criteria

There are no specific dermoscopic patterns or structures that can differentiate Miescher nevus from other intradermal nevi. The most com- mon dermoscopic pattern associated with the Miescher nevus is the homogeneous globular pattern with focal and symmetric arrangement of dots and globules arranged in cobblestone distribution [3]. The globules can have light to dark brown, and occasionally blue, colors. These lesions often have light-brown or skin-colored homogeneous structureless area. Histologically, the globules correlate with nests of nevus cells.

In addition to the globules, Miescher nevus can have “comma-shaped” blood vessels and milia.

Pigmented networks, a hallmark structure of melanocytic nevi, are generally not seen in Mi- escher nevus, because like an intradermal ne- vus, there is no junctional component.

III.13.4 Relevant Clinical Differential Diagnoses

Stereotypical Miescher nevi are relatively easy to diagnose. The differential diagnosis of medi- um and small intradermal nevus includes a neurofibroma and a fibrous papule of the face.

140 S.Q. Wang, H.H. Rabinovitz, A.W. Kopf

III.13

III.13.5 Histopathology

Histopathologically, Miescher nevus is an intra- dermal nevus with no junctional component. At scanning magnification, Miescher nevus is a symmetrical, dome-shaped papule. The nevus cells are distributed in a wedge shape and ar- ranged deep into the reticular dermis. Because the nevus is commonly located on the face, nu- merous folliculosebaceous units can be seen on the tissue sections. By and large, the adenxa are avoided by the nevus cells. At a higher magnifi- cation, the nevus cells show “maturation” with large and more pigmented nevus cells on top and smaller cells in the deeper dermis.

III.13.6 Management

Miescher nevus is benign. It is very rare that these nevi are associated with a melanoma. For cosmetic reasons, most Miescher nevi can be re- moved with either shave or punch excision. It is unnecessary to remove the entire nevus, and the surgical specimen should be submitted for his- topathological examination because rarely in- completely removed intradermal nevi can recur and give rise to lesions which can be easily mis- taken for melanoma clinically and histopatho- logically. Access to the original biopsy sections reveals that the original lesion was completely benign. It is highly unlikely that the recurrence of pigmentation in the residual scar is melano- ma.

III.13.7 Case Studies

A 45-year-old Caucasian man presented with more than 5 years history of asymptomatic pap- ule on the left cheek. Clinically, the lesion was soft, exophytic, and about 1 cm in diameter.

Dermoscopic examination showed the presence of blood vessels and faint clusters of brown glob-

ules within a large homogeneous structureless area. The patient was reassured about the be- nign nature of this lesion, and no treatment was performed.

III.13.7.2 Case 2

A 39-year-old Caucasian man presented with a brown pigmented mole on the left chin within the bearded region. He reported occasional traumas to the area when he shaves. The mole was not painful. Clinically, it was a 1.3-cm brown mole with a mammilated surface.

Dermoscopic examination showed clustered light-brown globules with cobblestone arrange- ment and structureless area. Because of frequent trauma from shaving, the mole was shave re- moved.

Fig. III.13.1. Case Study

Miescher Nevus Chapter III.13 141

C

Core Messages

■ Miescher nevus is an intradermal acquired nevus commonly located on the face.

■ As a rule, Miescher nevus is benign but may be uncommonly be associated with a melanoma.

■ Dermoscopically, most Miescher nevi reveal a variation on the theme of a homogeneous globular pattern.

References

1. Ackerman AB, Magana-Garcia M. Naming acquired melanocytic nevi: Unna’s, Miescher’s, Spitz’s, Clark’s.

Am J Dermatopathol 1990; 12: 193–209

2. Miescher G, Albertini A von. Histologie de 100 case de naevi pigmentaires d’apres les methods de Mas- son. Bull Soc Fr Dermatol Syph 1935; 42: 1265–1273 3. Bauer J, Blum A. Dermoscopic features of common

melanocytic nevi of the junctional, compound, and dermal type. In: Marghoob AA, Braun RP, Kopf AW (2005) Atlas of dermoscopy. Taylor and Francis, UK, pp 181–188

Fig. III.13.2. Case Study