An unusual case of an osteosarcoma arising in a leiomyoma of the uterus

Abstract

Leiomyoma is the most common uterine neoplasm. It has several histological variants such as atypical, cellular, myxoid, and epithelioid. Leiomyoma with heterologous elements is a rare variant of leiomyoma, which may contain heterologous elements such as fat, skeletal muscle, and chondroid and osseous tissues. The heterologous sarcomatous differentiation is also rarely seen. We report on a 53-year-old woman who was admitted with abnormal vaginal bleeding and symptoms related to an abdominal mass. She had a huge uterine leiomyoma that contained osteosarcomatous differentiation in several foci. Although malignant progression for leiomyoma is exceedingly rare, when it occurs it may result not only in a leiomyosarcoma but also in a heterologous sarcomatous differention. We have reported histopathological, immunohistochemical, and clinical features of this rare case and reviewed the published studies.

Figure 1

Macroscopic section (1A) and radiographic appearance (1B) of the mass (Arrows: radiopaque calcification foci).

Figure 2

Histopathological features of the mass. A: Junction of the leiomyoma (lower part) and osteosarcomatous (upper part) areas are seen (HE stain, ×100). B: Atypical mesenchymal cells and numerous osteoclast type giant cells are near the osseous metaplasia area (HE stain, ×100). C: Atypical mesenchymal cells have high mitotic count and were producing osteoid (HE stain, ×400). D: Osteoclast type giant cells are positive with CD 68 (Diamino benzidine, ×100).