Peripartum pseudomalignant myositis ossificans of the finger.

Two cases of pseudomalignant peripartum myositis ossificans of the finger are reported. The benign diagnosis is confirmed by the histologically characteristic zone phenomenon, consisting of a transition from an inner zone of proliferating spindle cells to a middle zone of well-oriented osteoid and finally to an outer zone of mature bone. In Case No. 1, because of the question of malignancy, a ray amputation was performed. In Case No. 2, the patient was observed during the peripartum period to show diminution in the size of the tumor. The lesion was eventually treated by local excision.