Mucocele of the vermiform appendix misdiagnosed as an adnexal mass on transvaginal sonography

Mucocele of the vermiform appendix is a rare entity that may mimic a right-sided adnexal mass. We describe a case of appendiceal mucocele in a 78-year-old woman that was initially misdiagnosed as a potentially malignant right ovarian tumor and briefly review the literature on sonographic features of this entity. It is important to improve preoperative diagnosis so as to prevent rupture of mucocele at surgery, which may lead to pseudomyxoma peritonei, and also to seek intraoperatively for the presence of synchronous colorectal neoplasms.