Low-grade appendiceal mucinous neoplasm with disseminated peritoneal adenomucinosis involving the uterus, mimicking primary mucinous endometrial adenocarcinoma: a case report.

We present a patient with a low-grade appendiceal mucinous neoplasm, resulting in disseminated peritoneal adenomucinosis (pseudomyxoma peritonei) with uterine involvement, and mimicking primary mucinous endometrial adenocarcinoma. On immunohistochemistry, neoplastic glands were cytokeratin 7-negative and cytokeratin 20-positive, indicating a gastrointestinal origin rather than a primary ovarian mucinous neoplasm. A diagnosis of uterine metastasis of appendiceal origin was made, based on the constellation of clinicopathological findings, that is, preceding appendiceal neoplasm, peritoneal involvement, absence of coexisting prototypical endometrioid adenocarcinoma or endometrial hyperplasia. The patient underwent hysterectomy and there was no evidence of disease progression at the 12-month follow up. This suggested the indolent nature of this particular neoplasm, despite its advanced stage.