Uterine leiomyoma is the most common benign mesenchymal tumor of the uterus occurring in females of reproductive age group. It is derived from the smooth muscle. Leiomyomas usually show degenerative changes; however, metaplastic changes are relatively unusual. Lipomatous metaplasia and chondroid metaplasia in leiomyoma have been reported occasionally; however, both osseous and cartilaginous metaplasia of uterine leiomyoma is extremely rare.

A 39-year-old female presented with abnormal uterine bleeding and abdominal discomfort. Pelvic ultrasonography revealed a large subserosal fibroid with degenerative changes. Abdominal hysterectomy was done and the specimen showed a large fibroid with gray white areas on gross examination. Microscopy revealed leiomyoma with osseous and cartilaginous metaplasia, hyaline and myxoid degeneration. Other findings in the specimen were adenomyosis and chronic cervicitis with nabothian cyst.

Leiomyoma shows a wide spectrum of histopathological features, but osseous and cartilaginous metaplasia remains a rarely reported entity. Osseous and cartilaginous metaplasia may create a diagnostic dilemma; adequate sampling of the gross specimen and care histopathological examination can confirm the benign behavior of this entity and to rule out sarcomas with heterologous elements.