Low-grade appendiceal mucinous neoplasm mimicking an adnexal mass.

We present a rare case of malignant epithelial neoplasm of the appendix, an uncommon disorder encountered in clinical practice, which poses a variety of diagnostic and therapeutic challenges. We report a particular case in which the appendix was abnormally located in the pelvis, mimicking an adnexal mass. Therefore, it was difficult to make the preoperative diagnosis on clinical examination, imaging studies and laboratory tests and we discovered the lesion during the diagnostic laparoscopy. No lymphadenopathy or mucinous ascites were found. The case was completely handled via the laparoscopic approach keeping the appendix intact during the operation. The frozen section, the detailed histopathology overview as well as multiple immunostaining with a complex panel of markers report diagnosed a low-grade appendiceal mucinous neoplasm (LAMN) with no invasion of the wall. No adjuvant therapy was considered needed. At a one-year follow-up oncological assessment, the patient was free of disease. In women with cystic mass in the right iliac fossa an appendiceal mucocele should be considered in the differential diagnosis. Laparoscopic appendectomy can represent an adequate operation for the appendiceal mucinous neoplasm if the histological report is clear and surgical precautionary measures are taken.