Neuroendocrine carcinoma of the gall bladder: A clinicopathological report of 56 Cases from a tertiary care cancer center in North India.

Background: Gall bladder (GB) is a rare site of neuroendocrine carcinoma (NEC). Gallbladder neuroendocrine carcinoma (GB-NEC) comprises only ~0.2% of all gastrointestinal NECs and 4% of all GB cancers. In the published literature, only a few isolated case reports and rare case series of GB-NEC are available. Worldwide, the largest series of GB-NEC reported is of 19 cases from India. In this study, we present clinicopathological features of 56 cases of GB-NEC diagnosed in a tertiary care cancer hospital of northern part of India.

Aims: To study the clinicopathological and immunohistochemical features of GB-NEC from the archives.

Methods: Retrospective data of GB-NEC, diagnosed over 53 months were collected from institutional electronic medical records. Hematoxylin and eosin (H and E) stained slides and corresponding immunohistochemistry slides were reviewed and included in the study. Data was compiled and basic statistical analysis was done.

Results: GB-NEC constituted 3.19% (n = 56/1752) of all GB carcinomas. Histological types of GB-NEC were: small cell NEC (96.4%, n = 54), large cell NEC (n = 1), and NEC with sarcomatous differentiation (n = 1). The diagnosis was ratified by use of combination of two neuroendocrine markers in varying combination comprising of Synaptophysin, chromogranin and INSMI1. Ki-67 index ranged from 50%-80% in 6 cases and more than 80% in 10 cases where count of mitotic figures was limited by extensive areas of necrosis. Follow-up of 6-8 months was available for 22 patients out of which 21 cases were living with disease. Twenty-two patients were treated with palliative chemotherapy.

Conclusions: GB-NEC is a rare and aggressive malignancy with poor prognosis due to advanced clinical stage of presentation and limited availability of treatment options.