Primary ovarian leiomyoma: Imaging in a rare entity

Primary ovarian leiomyoma is a very rare benign mesenchymal tumor arising from the smooth muscle of walls of ovarian blood vessels. It is usually seen between 20 65 years of age. Being asymptomatic in many patients, these are incidentally detected. Ultrasonography and magnetic resonance imaging are preferred modality while imaging these lesions. Hereby we present a case of a 35-year-old female with incidentally detected right ovarian mass lesion which was hypointense on ultrasonography, hypointense on both T1W and T2W images, and on histopathology confirmed as primary ovarian leiomyoma. T1- and T2-weighted hypointensity on MRI with early homogenous postcontrast enhancement help in its diagnosis, though many a time it is difficult to differentiate it from other mesenchymal fibrous tumors such as fibroma and fibrothecoma. Histopathology and immunohistochemistry remain the mainstay in final confirmatory diagnosis. It is important to keep this entity in the differential diagnosis of solid T1 and T2 hypointense lesions of the ovary.