Bilateral Ovarian Fibromatosis in a Postmenopausal Female: A Case Report with Emphasis on MRI Findings and Differential Diagnosis

Ovarian fibromatosis is a rare non-neoplastic condition that causes ovarian enlargement in women, typically around the age of 25. This enlargement is due to the proliferation of the collagen-producing ovarian stroma. On T2-weighted MRI, a key diagnostic feature of ovarian fibromatosis is the ‘black garland sign,’ characterized by multilobulated very low signal intensity along the ovarian surface. This condition also features the preservation of normal ovarian stroma or follicles internally. We present a case involving a 65-year-old postmenopausal female who was pathologically misdiagnosed with ovarian fibroma. However, the diagnosis was later revised to ovarian fibromatosis based on characteristic MRI findings. The case report discusses the differential diagnosis and pathologic findings associated with ovarian fibromatosis.