38
Mucinoses
In this group of disorders, there is deposition of glycosaminoglycans, previously referred to as mucopolysaccharides (‘mucin’), within the skin, especially the dermis. Most frequently, the deposit is composed of hyaluronic acid. While several of the entities are idiopathic, underlying disorders include autoimmune thyroid disease, a monoclonal gammopathy, and diabetes mellitus.
Scleredema
• Symmetric diffuse induration of the skin, usually limited to the upper back and posterior neck, that may require palpation to be appreciated; a peau d’orange appearance may be present with prominent follicular orifices, and occasionally there is blanching erythema in the sites of involvement (Fig. 38.1).
Fig. 38.1 Scleredema in association with diabetes mellitus. Diffuse induration of the upper back and neck with overlying erythema.
• DDx: systemic sclerosis (diffuse form), scleromyxedema, and other sclerodermoid disorders (see Table 35.4); occasionally, cellulitis if erythema is present.
Scleromyxedema/Papular Mucinosis
• A spectrum of clinical findings that varies from multiple linear arrays of firm, 2- to 3-mm, waxy, skin-colored papules (Fig. 38.2) to diffuse induration of the skin with thickened folds, including leonine facies (Fig. 38.3; Table 38.1); involvement is symmetric and often widespread.
Fig. 38.2 Scleromyxedema/papular mucinosis. A, B Numerous monomorphic, firm, skin-colored papules which can have a linear arrangement (most obvious on the upper back).
Fig. 38.3 Scleromyxedema/papular mucinosis. Thickening of the skin of the forehead (A) and trunk (B), leading to deep furrows and folds. Scleromyxedema is one of the causes of leonine facies. Courtesy, Joyce Rico, MD.
Table 38.1
Leonine facies – associated dermatologic diseases.
Additional causes include sarcoidosis, mastocytosis, multicentric reticulohistocytosis, and progressive nodular histiocytosis.
• DDx:
