Israel Medical Association Journal

Neuroendocrine tumors (NETs) are a group of rare, heterogenous neoplasms that maintain unique morphologic and clinical features of neuroendocrine neoplasia and account for approximately 0.5% of all newly diagnosed malignancies. NETs are divided into two groups based on their histopathological morphology: well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs). Well differentiated NETs are classified as G1, G2, or G3 based on their proliferation rate, whereas NECs are highly proliferative and poorly differentiated by definition [1]. Neuroendocrine neoplasms can occur almost anywhere in the body; however, they are most often seen in the gastrointestinal tract, pancreas, and lungs [2]. The extrahepatic bile duct is one of the rarest primary sites for NETs, accounting for 0.1% to 0.2% of NETs of the gastrointestinal tract [3]. Signet ring cell bile duct NETs are extremely uncommon and have no established incidence and prognosis due to their rarity. There is sparse information available regarding these tumors, and only a few cases have been reported in the literature to date. In this report, we presented the clinical course and surgical management of a 31-year-old female patient with a Klatskin signet ring cell NET.

Objectives: To examine the proliferative index, as expressed by Ki67, in various subtypes of basal cell carcinoma, and to assess its relationship to various histological and clinical variables.

Methods: In this retrospective study 51 lesions of BCC were examined. In each case, the following data were gathered: demographic (age and gender), anatomic location, size of the lesion, and clinical follow-up.  Each case was stained immunohistochemically with anti-Ki67 antigen (MIB-1), and the proliferative index was determined. Histologic analysis was performed for the following data: presence of an ulcer, intensity of inflammatory infiltrate, histologic subtype, mitotic count, and the presence of perineural invasion.

Results: Basal cell carcinoma exhibited a wide variation of proliferative indices, ranging from 1% to 61%. A significant statistical correlation was observed between the proliferative index and the mitotic activity, tumor ulceration and brisk tumor-infiltrating lymphocytes.

Conclusions: The wide variation in the degree of proliferation (from almost no activity to highly proliferative tumors) suggests that basal cell carcinoma exhibits a wide spectrum of biological characteristics. Ulcerated lesions were characterized by high proliferative index. No true correlation was demonstrated between the proliferative index and the aggressive histologic subtypes, implying that other factors were more biologically significant. The degree of proliferation also showed significant statistical correlation with the degree of tumor infiltration by lymphocytes. The significance of this proliferation-associated increased immunogenicity needs to be further studied.