Diffuse muscular calcification with subcutaneous cysts

OBJECTIVE: Diffuse muscular calcification was rare myopathological change due to abnormal metabolism of calcium, which was mainly found in dermatomyositis and myositis ossificans progressiva. Here we reported a case of diffuse muscular calcification that clinically mimicked myositis ossificans progressiva. The disease might be a new type of congenital calcium metabolic disease. METHODS: A 15-year-old girl developed subcutaneous cysts in the wrist and ankle when she was 1 year old. At the age of 9, she developed recurrent fever with myalgia, fatigue and diffuse muscular calcification. It was difficult for her to squat, run or walk. Protuberance presented in the subcutaneous tissue of her trunk. Some nodules ruptured with outflow of chalky material. ESR, ENA, RF, CRP, PTH, CK were in normal limits. EMG was unremarkable. X-ray confirmed diffuse calcification in the muscle and subcutaneous tissues. Biceps muscle biopsy was performed. RESULTS: Numerous inflammatory cells infiltrated around vessels in the perimyosium with perifascicular muscle fiber atrophy and degeneration. Many RRF and SDH positive fibers were also observed. EM showed tubular reticular inclusions in vascular endothelium. CONCLUSION: Diffuse muscular calcification indicated existence of systemic calcium metabolic abnormality. As the clinical symptoms and distribution pattern of calcification were different from dermatomyositis with subcutaneous calcification and myositis ossificans progressiva, our case might be a new type of disease. The microvascular changes might result in the lesion of muscle fibers.