MYOSITIS-OSSIFICANS CIRCUMSCRIPTA AND ISCHEMIC MUSCULAR INJURY - 2 CASES

Introduction, - Non-traumatic myositis ossificans circumscripta is a r elatively rare, well defined entity. The pathogenic role of ischemia i n its development is discussed. Exegesis. - We report two cases of myo sitis ossificans circumscripta that occurred in the harmstring muscle respectively 22 and 35 years after ischemic muscular injury in the sam e site. Clinical and radiologic informations and follow-up were reexam ined showing that patients are usually young and that the disease is e qually distributed between both genders. Though the lesion may develop in various muscle, it is preferentially observed in proximal sites. M ost patients have a history of localized pain or tenderness accompanie d by swelling of the affected site. Following a 5- to 12-week increase , the soft-tissue mass is less sensitive and better defined. it may al so resolve in less than 3 years. Conclusion. - Results of X rays, comp uterized tomography, MR imaging and biopsy are reviewed. Histologicall y, this lesion main feature is peripheral bone maturation within three areas. Mechanisms (traumatic or not) underlying these lesions are unk nown. To our knowledge, only one published case would be comparable to ours. Proliferation followed by change in mesenchymal cells leading t o heteropic ossification must be regarded as a consequence of either i schemia or repeated micro-trauma occurring during muscle shortening. ( C) 1998 Elsevier, Paris.