Linear and micronodular neuroendocrine cell hyperplasia in an ovarian mucinous cystadenoma

We report a rare case of an ovarian mucinous cystadenoma in which there were peculiar neuroendocrine micronests composed of gastrin-immunoreactive cells. There was no clinical evidence of hypergastrinemia. The mucinous component of the neoplasm was represented by columnar cells mostly expressing a gastric phenotype with MUC5AC and claudin 18 positivity, which was consistent with the presence of interspersed gastrin cells. The tumoral stroma displayed areas of luteinization with cells intensely positive for α-inhibin, MART-1 and calretinin.