Myositis Ossificans - Morphology

Microscopic Features: At the interface between the innermost and intermediate zones of myositis ossificans there is an admixture of fibroblasts and osteoblasts and appearance of poorly-defined trabeculae with variable amounts of osteoid. Hypercellular chondroid foci may be present in some cases. Taken out of context, such foci may be mistaken for chondrosarcoma or chondroblastic osteosarcoma.