Low-grade Appendiceal Mucinous Neoplasm Presenting as Adnexal Mass: A Case Report.

An appendiceal mucocele is a dilatation of the appendix and it is the result of benign or malignant diseases, which cause the obstruction of the appendix and the consequent accumulation of mucus secretion. The preoperative diagnosis is difficult due to non-specific clinical manifestations of the disease. We present a case of an 83-year-old female patient with a history of breast cancer that was referred to our hospital for an evaluation of a right adnexal mass discovered during her yearly follow-up. The patient underwent an exploratory laparotomy with a provisional diagnosis of a right adnexal mass. A perioperative, appendiceal mucocele was diagnosed. She underwent a formal appendectomy and histopathology of the specimen revealed a low-grade mucinous neoplasm. Appendiceal mucinous neoplasms represent a rare form of pathology among all appendectomy specimens. A preoperative diagnosis is difficult due to the lack of specific symptoms and it is often misdiagnosed as an adnexal mass. The perforation of the appendix and subsequent extravasation of its contents into the abdominal cavity may lead to pseudomyxoma peritonei, which has a very poor prognosis if not treated properly.