Rupture of appendiceal mucocele due to endometriosis: report of a case.

We report a rare case of a mucocele of the appendix due to endometriosis which accidentally ruptured prior to surgery. A 56-year-old woman was referred to our institution for further evaluation of a cecal tumor. Colonoscopy showed a submucosal tumor at the appendiceal orifice in the cecum. Computed tomography and magnetic resonance imaging showed a well-circumscribed mass measuring 4 cm in diameter in the right lower quadrant. A preoperative diagnosis of a simple mucocele of the appendix was established. At laparotomy, a mucocele was identified in the right side of the abdomen; however, part of the mucocele had ruptured and yellow mucin was seen around the cecum. An ileocecal resection was performed. Histopathological examination was consistent with a mucocele of the appendix due to endometriosis. Cytology specimens from the yellow mucin showed few proliferating epithelial cells with a mild degree of cytological and architectural atypia. Mechanical pressure due to excess anteflexion during administration of epidural anesthesia may have contributed to the rupture of the mucocele. It is important to handle a mucocele of the appendix with great care to avoid rupture at the time of operation, including during the administration of epidural anesthesia.