Abstract

Scleromyxedema is a rare progressive fibromucinous disease characterized histologically by diffuse mucin in the dermis, proliferation of fibroblasts, and increased collagen deposition. Clinically, patients present with waxy papules and diffuse induration, often with cardiovascular, gastrointestinal, pulmonary, renal, neurological, and rheumatological complications. Most are found to have an underlying paraproteinemia and few cases progress to symptomatic myeloma. We present the case of a 66-year-old man with a 5-year history of scleromyxedema on intravenous immunoglobulin (IVIG) who presented with worsening skin thickening involving the legs, knees, thighs, lower abdomen, shoulder, nose, and mouth. Given the progression of his symptoms, repeat punch biopsies were performed of the right thigh to confirm diagnosis of scleromyxedema. Histopathology demonstrated mucinous degeneration of the collagen with interstitial infiltrates of histiocytes and focal lymphohistiocytic infiltrates, most suggestive of a granuloma annulare (GA)-like reaction. CD163 immunohistochemical staining highlighted the histiocytic component of the infiltrate. In the context of his clinical presentation and monoclonal gammopathy, the diagnosis was confirmed as progression of his scleromyxedema with GA-like histology. Unfortunately, the patient underwent bone marrow biopsy and met criteria for multiple myeloma; he continued treatment with IVIG, with the addition of lenalidomide, bortezomib and dexamethasone (RVD) regimen. This histological variant of scleromyxedema has been rarely described and increased awareness may expedite diagnosis and treatment. This case adds to the small number in the literature describing scleromyxedema with GA-like histology and highlights the importance of clinicopathological correlation in diagnosis.