Multiple pulmonary leiomyomatous hamartoma with secondary ossification

A 31-year-old woman presented with multiple pulmonary leiomyomatous hamarto ma (MPLH) with secondary ossification. She had a past history of parosteal osteosarcoma. The pulmonary lesions were composed of spindle-shaped cells a rranged in interlacing fascicles, among which glands or duct-like spaces we re scattered. As some lesions contained bony tissues, it was unclear whethe r or not the pulmonary lesions were metastases of parosteal osteosarcoma. H owever, the majority of spindle-shaped cells were positive for a-smooth mus cle actin, including cells proliferating around the bony tissues. Clonality analysis using a target of human androgen receptor (HUMARA) gene disclosed that the pulmonary nodules were polyclonal, These findings do not indicate that the lesions were metastatic. We would like to emphasize that MPLH can show osseous metaplasia.