15 Gallbladder
(Carcinoid tumors and sarcomas are not included.)
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SUMMARY OF CHANGES
• The T and N classifications have been simplified in an effort to separate locally invasive tumors into potentially resectable (T3) and unresectable (T4).
• There is no longer a distinction between T3 and T4 based on the depth of liver invasion.
• Lymph node metastasis is now classified as Stage IIB, and Stage IIA is reserved for large, invasive tumors (resectable), without lymph node metastasis.
• Stage grouping has been changed to allow Stage III to signify locally unresectable disease and Stage IV to indicate metastatic disease.
C23.9 Gallbladder
INTRODUCTION
Cancers of the gallbladder are staged according to their depth of penetra- tion and extent of spread. These cancers frequently spread to the liver, which is involved in 70% of patients at the time of surgical evaluation. Malignant tumors of the gallbladder can also directly invade other adjacent organs, particularly the common bile duct, the duodenum, and the transverse colon. Gallbladder cancers are insidious in their growth, often metastasizing early, before a diagnosis is made. Tumors can also perforate the wall of the gallbladder, eventually causing intra-abdominal metastases, carcinomatosis, and ascites. Because gallbladder cancer is uncommon and is usually diagnosed late, physicians have tended to ignore anatomic staging, even though its importance for survival, management, and prognosis has been emphasized. Many cases are not suspected clinically and first discovered at laparoscopy or incidentally by the pathologist. More than 75%
of carcinomas of the gallbladder are associated with cholelithiasis. Survival cor- relates with the stage of disease.
ANATOMY
Primary Site. The gallbladder is a pear-shaped saccular organ located under the liver in the gallbladder fossa. It has three parts: a fundus, a body, and a neck that tapers into the cystic duct. The wall of the gallbladder is much thinner than that of the intestine and lacks a circular and transverse muscle layer. The wall has a mucosa (that is, an epithelial lining and lamina propria), a smooth muscle layer analogous to the muscularis propria of the small intestine, perimuscular connective tissue, and serosa. In contrast to the intestine, there is no submucosa.
Along the attachment to the liver, no serosa exists, and the perimuscular con- nective tissue is continuous with the interlobular connective tissue of the liver.
Tumors that arise in the cystic duct are classified according to the scheme for the extrahepatic bile ducts.
Regional Lymph Nodes. Accurate tumor staging requires that all lymph nodes that are removed be analyzed. Optimal histologic examination of a re- gional lymphadenectomy specimen should include analysis of a minimum of three lymph nodes. The regional lymph nodes include the following: hilar, celiac, periduodenal, peripancreatic, and superior mesenteric. The hilar nodes include the lymph nodes along the common bile duct, hepatic artery, portal vein, and cystic duct (Figure 15.1).
Metastatic Sites. Cancers of the gallbladder usually metastasize to the peri- toneum and liver and occasionally to the lungs and pleura.
DEFINITIONS Primary Tumor (T)
TX Primary tumor cannot be assessed T0 No evidence of primary tumor Tis Carcinoma in situ
T1 Tumor invades lamina propria or muscle layer T1a Tumor invades lamina propria (Figure 15.2) T1b Tumor invades muscle layer (Figure 15.2)
T2 Tumor invades perimuscular connective tissue; no extension beyond serosa or into liver (Figure 15.3)
T3 Tumor perforates the serosa (visceral peritoneum) and/or directly in- vades the liver and/or one other adjacent organ or structure, such as the stomach, duodenum, colon, pancreas, omentum, or extrahepatic bile ducts (Figures 15.4A, B)
T4 Tumor invades main portal vein or hepatic artery or invades two or more extrahepatic organs or structures (Figures 15.5A, B)
FIGURE 15.1. Regional lymph nodes of the gallbladder.
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T1a T1b
Subserosa Serosa Lamina propria Muscle layer
FIGURE 15.2. T1a is defined as tumor invading lamina propria; T1b is defined as tumor invading muscle layer.
Lamina propria Muscle layer T2
T2
Subserosa Serosa
FIGURE 15.3. Two views of T2: tumor invading perimuscular connective tissue (illustration and inset below dotted line) and tumor with no extension beyond serosa into the liver (illustration above dotted line).
T3
T3
A T3
B
FIGURE 15.4. A. Two views of T3: tumor perforating the serosa (visceral peritoneum) (below the dotted line) and/or directly invading the liver (above the dotted line). B. T3 may also be defined as tumor invading one other adjacent organ or structure, such as the duodenum (as illustrated), or the stomach, colon, pancreas, omentum, or extrahepatic bile ducts.
Regional Lymph Nodes (N)
NX Regional lymph nodes cannot be assessed N0 No regional lymph node metastasis
N1 Regional lymph node metastasis (Figure 15.6) Distant Metastasis (M)
MX Distant metastasis cannot be assessed M0 No distant metastasis
M1 Distant metastasis
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T4
Main portal vein Hepatic artery
A
T4
Hepatic flexure of colon Duodenum
B
FIGURE 15.5. A. T4 is defined as tumor invading main portal vein or hepatic artery (as illustrated), or invading two or more extrahepatic organs or structures.
B. T4 invading two or more extrahepatic organs or structures (here, colon and duodenum).
N1
FIGURE 15.6. N1 is defined as metastasis to regional lymph nodes.
STAGE GROUPING
0 Tis N0 M0
IA T1 N0 M0
IB T2 N0 M0
IIA T3 N0 M0
IIB T1 N1 M0
T2 N1 M0
T3 N1 M0
III T4 Any N M0
IV Any T Any N M1
