May Be Caused by

 Common

Hemangioma

Hematoma

Lipoma

Myositis ossificans

Osteosarcoma

Synovial osteochondromatosis

Synovial sarcoma

 Uncommon

Benign mesenchymoma

Calcifying aponeurotic fibroma

Chondroma

Chondrosarcoma

Desmoid tumor

Epithelioid sarcoma

Fibrosarcoma

Hemangioendothelioma

Hemangiopericytoma

Leiomyoma

Leiomyosarcoma

Liposarcoma

Malignant fibrous histiocytoma

Malignant mesenchymoma

Malignant peripheral nerve sheath tumor

Myofibromatosis

Neurofibroma

Schwannoma

Tumoral calcinosis