Amar S, Mountjoy L and West M
Neuroendocrine tumors (NET) of the gallbladder are extremely rare and coexistence with an adenocarcinoma in the same specimen has only rarely been reported. There is a newly defined entity of mixed adenoneuroendocrine carcinoma (both components should be >30%), but not all cases qualify. It is unclear if the NET dedifferentiates into the adenocarcinoma elements or vice versa. We report the case of a woman who presented with non-specific cholecystitis like symptoms and was found to have elements of a high-grade NET of the gallbladder with an area of adenocarcinoma. The prognosis is determined by the high-grade NET element and the patient was treated with surgery followed by concomitant chemo-radiation. The incidence and prevalence of NET ranges from 1.09 per 100,000 individuals over the past 50 years, with a 6.4-fold increase in incidence since 2012.
Diagnosis of NET are commonly made post-surgically, and thus patients will likely present with symptoms ranging from vague epigastric pain, anorexia, weight loss, and jaundice. A patient who present without carcinoid symptoms, including diarrhea, flushing, and skin rashes, defines a poorer prognosis due to poorly differentiated neuroendocrine cells. This case reports a woman with a long history of epigastric pain and bloating who was found to have a primary adenocarcinoma of the gallbladder with dedifferentiation into high grade NET. Pathology showed poorly differentiated nest of neuroendocrine cells within the high-grade adenocarcinoma. Cases of dedifferentiated neuroendocrine cancer of the gallbladder are extremely rare and this case highlights unique pathologic findings. Currently, it is unclear whether pathological findings of adenocarcinoma with neuroendocrine features, arises from linear plasticity, of which specified DNA alterations induce transformation, or that this is a subtype of mixed tumor types.