Proliferative myositis. A case report with fine structural analysis.

A report is given on a case of proliferative myositis in a 75 year old woman. By fine structural analysis it can be shown, that the characteristic giant cells in proliferative myositis are mesenchymal cells with an intensive protein metabolism. They can be compared to fibroblasts; for a myogenic origin of these cells we found noevidence. Furthermore, various stages in the development and function of the proliferating cells were observed, by which the course of the disease can be expalined.