Scleromyxedema histopathologically mimicking hypercellular fibrous papules (angiofibomas): Case report of an unusual histopathological presentation

Scleromyxedema

Scleromyxedema is a rare, cutaneous deposition disorder from the group of mucinoses, which can affect multiple organs and is virtually always associated with a monoclonal gammopathy. Cutaneous manifestations are usually generalized, 2 to 3 mm sized, dome-shaped or flat-topped, waxy, slightly red to skin-colored papules and sclerodermoid indurations. Neurological, rheumatological, cardiovascular, gastrointestinal, respiratory tract, renal and ophthalmologic manifestations can occur, with decreasing frequency. A serious and potentially lethal complication is the dermato-neuro syndrome which manifests with flu-like prodromes followed by fever, convulsions and coma. Untreated, scleromyxedema usually takes an unpredictable and potentially lethal progressive disease course over several years. According to a widely acknowledged classification by Rongioletti a diagnosis of scleromyxedema can be rendered when (1) generalized, papular and sclerodermoid eruption, (2) a histological triad of mucin deposition, fibroblast proliferation and fibrosis, and (3) monoclonal gammopathy are present, and (4) thyroid disease is absent. Apart from the classic microscopic triad, an interstitial granuloma annulare like pattern was also described. The pathogenesis of scleromyxedema is unknown. A potential role for various, as yet unknown serum factors has been discussed. An unequivocal causal relationship between paraproteinemia and disease manifestations could not be established to date. High dose intravenous immunoglobulins (IVIg) are the first-line treatment of choice according to the most recent European guidelines.