Abstract
A gallbladder neuroendocrine neoplasm (GB‑NEN) is a bizarre heterogeneous neoplasm arising from neuroendocrine cells, which are present in minimal amounts on the GB mucosa either due to conversion of undifferentiated stem cells, chronic inflammation and resulting in pathological metaplasia or switching of GB adenocarcinoma to neuroendocrine one. Among all the GB malignancies, GB-NEN accounts for approximately 2.1%. A 41-year-old lady presented with right upper abdomen pain and distension for 2 weeks. Contrast CT showed heterogeneously enhancing wall thickening involving fundus-body of the GB with large exophytic component involving segments IV/V of liver, peripheral enhancement and central low attenuating necrotic areas. Middle hepatic and left branch of portal vein was filled with enhancing lesion, tumor thrombi. She underwent left trisectionectomy followed by adjuvant chemotherapy. Postoperative biopsy reported as poorly differentiated unifocal small cell GB-neuroendocrine carcinomas (GB-NEC). Resected margins were free of tumor with periportal lymph nodes negative for tumor. Follow-up PET-CT after six months of treatment completion shows no tumor recurrence or metastases. She has completed 12 months following the surgery and is asymptomatic. As the occurrence of GB-NEC is rare, there are little data regarding etiology, pathogenesis, treatment and prognosis of it. Even though metastasis is early and most frequent to lymph nodes, liver, lung and peritoneum, the presence of tumor thrombus in GB-NEC is rarely reported. Though most reports suggest very poor outcomes, radical surgery followed by adjuvant chemotherapy can yield good short-term results as seen in this case.