Mucinous Cystic Neoplasm of the Liver With Associated Neuroendocrine Carcinoma: A Case Report

Mucinous cystic neoplasms (MCNs) of the liver are relatively rare tumors that constitute less than 5% of liver cysts and are subcategorized into low/intermediate- and high-grade lesions based on the degree of epithelial dysplasia. An associated invasive carcinoma component occurs in 6% of cases, usually as adenocarcinomawith tubular growth. The liver is a frequent metastatic site for neuroendocrine carcinomas (NECs), whereas primary hepatic NECs are extremely rare. We present the case of a 63-year-old woman with a history of choledochal cyst, who now presented with abdominal pain. Computed tomography showed a multilocular cystic lesion in the liver. The cyst was surgically enucleated, and the histological examination revealed an MCN with low-grade dysplasia, with an associated invasive large cell NEC. To our knowledge, this is the first report in the literature of a biliary MCN with associated NEC.