Panniculitis, infection, and dermatomyositis: case and literature review

The most common cause of panniculitis (inflammation of the subcutaneous adipose tissue) is infection. Clinical panniculitis in dermatomyositis is rare. We found in the English literature 24 cases, including ours. Six cases involved children. Buttocks or thighs and arms were involved more frequently. Lobular panniculitis with lymphoplasmacytic infiltration was the usual pathology. Calcifications of the panniculus were found in 6/24 (25%) of the cases. Membrano-cystic changes were associated with worse prognosis. Sixteen of 18 cases (89%) without associated infection, responded to increased immunosuppression. Eighty-nine percent responded to steroids alone. Intravenous immune globulin (IVIG) was effective in steroid-resistant cases. No spontaneous improvement was reported. Three cases were associated with infection; Staphylococcus aureus in two and Mycobacterium chelonae in one. All three responded to antibiotics with simultaneous decrease of the immunosuppressive therapy. Concomitant infection may play a role in the worsening of panniculitis and needs to be aggressively identified and treated.