Abstract

A healthy 4-year-old boy presented with 2 months of episodic, painful bumps under the skin associated with headaches and fever. They started on the bilateral calves then spread to his forearms, thighs, feet, and lower back. Physical examination revealed symmetrically distributed pink nodules on the back and indurated annular erythematous plaques on the extremities. The clinical differential diagnosis included panniculitis, generalized morphea, and eosinophilic fasciitis. MRI showed diffuse fasciitis and soft tissue edema of the lower abdomen, pelvis, and lower extremities. Peripheral eosinophilia was absent. ESR and CRP were elevated, and ANA was 1:320 in a speckled pattern. Punch biopsy demonstrated a dense lobular panniculitis composed of foamy histiocytes, plasma cells, and small to medium-sized lymphocytes focally rimming adipocytes. There was mild septal sclerosis, but no visible fascia. The CD4:CD8 ratio was 4:1, and the infiltrate was negative for CD56, delta TCR, and EBER. T cell receptor clonality was negative. Rheumatology started empiric treatment for eosinophilic fasciitis with a systemic steroid taper, but the patient flared upon decreased dosing and developed subsequent cutaneous atrophy. A second incisional biopsy again demonstrated a lobular panniculitis, but without prominent fascial sclerosis or eosinophils, solidifying a diagnosis of lipoatrophic panniculitis. Work-up for associated causes including trauma, infection, connective tissue disease, alpha-1 antitrypsin, and pancreatitis was negative. Lipoatrophic panniculitis is a rare entity characterized by fever and recurrent tender subcutaneous nodules most commonly on the lower extremities of children, which heal with lipoatrophy. Some presentations have involved deeper structures with synovitis, tendonitis, and arthritis. This case highlights a previously unreported presentation of fasciitis and the critical role of clinicopathologic correlation in the diagnosis of lipoatrophic panniculitis.

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