A Rare Repeated Recurrence Of Myositis Ossificans In The Lateral Right Knee

Myositis ossificans (MO) is a benign condition characterized by abnormal heterotopic bone formation, typically involving the striated muscle and soft tissue. MO has an excellent prognosis but may appear clinically and radiologically as a malignant neoplasm. Sometimes the diagnosis of MO is very difficult to establish, even delayed. In the particular cases, when the calcific lesion appears in an atypical location in the body, MO is more likely to be misdiagnosed. A rare case of a MO in the lateral right knee was reported in this article, and surgical resection of the mass was performed. The final pathological diagnosis confirmed MO. Five months after the resective surgery a recurrence of MO took place and the patient underwent another surgical resection of the lesion. Three months later, the lesion reappeared for the third time in the same location. After a seven-year-four-month follow-up, the latest plain radiographs showed the MO to be still present in the lateral right knee. The range of motion of the affected knee and the neurologic examination of this patient were both normal. The cause of the multiple recurrence of MO was unknown. The biopsy of MO is the key factor to avoiding misdiagnosis.