Proliferative myositis: A case report and review of literature

Abstract

Proliferative myositis is a benign, reactive, pseudosarcomatous fibroblastic proliferation associated with bizarre giant cells resembling ganglion cells. It is most commonly seen in 5 th decade of life. It is a skeletal muscle counterpart of proliferative fasciitis, which clinically and histologically resembles it. It most commonly affects skeletal muscles of shoulder, thorax, and thigh. Trauma is considered to be most common etiological factor. Grossly, it presents as a discrete solitary nodular mass with irregular margins measuring 1-6 cm in size. Histopathological examination of tissue shows sheets of myofibroblasts amixed with large cells, which resemble ganglion cells. Immunohistochemical evaluation of the tissue shows positivity for vimentin and SMA and negativity for desmin in myofibroblasts, whereas ganglion cell-like cells are focally positive for SMA. We report a case of proliferative myositis in a 42-years-old female patient who presented with a slow-growing, painless, irregular swelling in left forearm 3 cm below the elbow.