Hospital: Hospital Ramon y Cajal.
Aut@r o Autores: S. Resano Pardo, I. Mota Goitia, I. Pecharroman De Las Heras, O. Sanz De Leon, A. Vicente Bartulos, C. Campos Ferrer.
The patient is a 46 years old woman who comes to the Emergency Service because she has functional impotency in the left shoulder and painful mass, it started a week ago and went worse. In the first technique, conventional Rx, we can see a calcified mass overlaying the humeral head. The calcification is mostly in the periphery of the theoric lesion. In the second technique, conventional CT without contrast, we can see a part of the calcified mass, which is located in the supraspinatus muscle, and plenty of inflammatory changes around it. Finally, we can see an MRI which is performed at the Radiology Service 2 days later: we confirm a big mass in the supraspinatus muscle and a lot of inflammatory changes (DP SPIR and T1w sequences).
Myositis ossificans (MO) is an inflammatory pseudotumor, generally located in a muscle. MO corresponds to an heterotopic metaplastic and non-malignant bone tumor, maybe developed due to a muscular trauma, but it is not always like this (sometimes, idiopathic). Quite a common presentation, as in this case, is a very inflammatory, rapidly growing, and painful muscular mass. In early phases it can be mistaken as a malignant soft tissue tumor. A key for the diagnosis is the dramatic onset of the symptoms, and the ossifications, which are peripheral and centripetal.
Pareostal osteosarcoma, some soft tissue sarcomas, and benign calcifications (gout, tumoral calcinosis, …) should be included in the differential diagnosis.
- Lacout A, Jarraya M, Marcy PY et-al. Myositis ossificans imaging: keys to successful diagnosis. Indian J Radiol Imaging. 2012,22 (1): 35-9 - Parikh J, Hyare H, Saifuddin A. The imaging features of post-traumatic myositis ossificans with emphasis on MRI