[A case of progressive ossifying myositis caused by gene mutation].

A 2-year-and-10-month-old boy presented with multiple masses in the neck and chest for over 3 months. The child had a history of unstable walking, with hard lumps visible at the injury sites after falls, which would resolve on their own. Following a recent injury, a mass was discovered in the posterior neck, protruding above the skin surface and accompanied by limited joint movement.