title: Invasive micropapillary variant of the gallbladder adenocarcinoma and its aggressive potential for lymph node metastasis.
abstract: An invasive micropapillary variant (IMPV) has recently been described in several organs but has not been reported in the gallbladder. It has been mentioned to have aggressive behavior with a high propensity for lymphovascular invasion, lymph node metastasis and poor clinical outcome. We analyzed the clinicopathologic findings of IMPV and compared them with those of a conventional adenocarcinoma in the gallbladder to clarify the highly aggressive potential of IMPV of gallbladder carcinoma. Ninety consecutive cases of surgically resected gallbladder carcinomas were studied for age, gender, type, depth of invasion and lymph node and distant metastases. Histologically, IMPV of gallbladder carcinoma was characterized by a small cluster of tumor cells lying within clear stromal spaces. This pattern mimicked extensive lymphatic invasion, but the cluster of tumor cells showed a distinctive retraction artifact from the surrounding stroma. In total, 20 (22.2%) cases had foci of IMPV, which ranged from 5% to 10% of the primary tumor tissue. Of those 20 cases, 17 (85.0%) carcinomas with IMPV also included lymph node metastasis, which was more frequent than in conventional carcinoma (32.8%, P < 0.001). Carcinomas with IMPV had a more advanced tumor status and showed severe lymphatic invasion (P = 0.001, P < 0.001, respectively). A multivariate regression analysis demonstrated that the presence of IMPV is an independent predictor of regional nodal metastasis (Odds ratio: 9.995, 95% confidence interval: 1.996-50.052, P = 0.005). IMPV is a useful predictor of regional lymph node metastasis in gallbladder adenocarcinoma.
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine, Toho University Omori Medical Center, Tokyo, Japan.
authors.forename: Seiichi
authors.initials: S
authors.lastname: Hara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kijima
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Okada
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Igarashi
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D002277:Carcinoma / Q000473:pathology*; D005706:Gallbladder Neoplasms / Q000473:pathology*; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis / Q000473:pathology; D016403:Lymphoma, Large B-Cell, Diffuse / Q000473:pathology; D015999:Multivariate Analysis; D009367:Neoplasm Staging; D012307:Risk Factors