Myositis ossificans (sporadic form)

Rare, non-hereditary, acquired clinical picture characterized by painful nodes along tendons and tendon sheaths. These can also occur within the musculature. The changes often occur after a verifiable local trauma, but more rarely they occur spontaneously.

Unsolved. S.a. under fibrodysplasia ossificans progressiva.

Mainly shoulder, neck, arms, lower legs, trunk localized; less often on the tongue or orally.

Rapidly growing, usually painful, 1.0-5.0 cm large, inflammatory subcutaneous plates or nodules as well as rough, painful, nodular indurations of the musculature which are caked to the covering skin and the subcutis.

In the dermis cell-rich, polymorphic infiltrates of epithelioid cells and some multinucleated bizarre, giant cells, heart-shaped lymphocytes, leukocytes, haemorrhages and haemosiderotic pigment. In older foci, calcification or extraosseous ossification can be detected. Subepidermally free stripes, dense, cellular infiltration of the striated musculature, partly with sarcolysis.

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2. Bauer AH et al (2018) Fibrodysplasia ossificans progressiva: a current review of imaging findings. Skeletal radiol 47:1043-1050.
3. Chevalier X et al (1993) Proliferative myositis as a complication of rheumatoid vasculitis. J Rheumatol 20: 1259-1260
4. Kent MS et al (2002) Proliferative myositis: a rare pseudosarcoma of the chest wall. Ann Thorac Surg 73: 1296-1298
5. Core WH (1960) Proliferative Myositis: a pseudosarcomatous reaction to injury. Arch catholic 69: 209-216
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