Scleromyxedema and Monoclonal Gammopathy
Scleromyxedema (SM), also known as generalized lichen myxedematosus (LM), is a cutaneous mucinosis. Although LM is considered a chronic nonlethal disease, its generalized form (SM) is associated most frequently with monoclonal gammopathy and other systemic disorders that may result in death.[1,2] By contrast, the more localized forms of LM are not associated with paraproteinemia and usually have no systemic manifestations. SM is a rare disease of unknown etiology that usually affects middleaged adults between 30 and 80 years of age.[3] It is characterized by a generalized papular and sclerodermoid eruption, mucin deposition, increased fibroblast proliferation, fibrosis, and monoclonal gammopathy, in the absence of thyroid disease. An increased production of hyaluronic acid by fibroblasts occurs, possibly due to paraprotein stimulation.[2,3]
Clinically, SM appears as a generalized eruption of 2 mm to 3 mm waxy lichenoid (flattopped) papules, often in a linear arrangement; lesions are most common on the hands, elbows, forearms, upper trunk, face, and neck. These lichenoid lesions coalesce, leading to induration of the underlying tissue that resembles scleroderma. Typical involvement of the glabella with deep longitudinal furrows can be reminiscent of leonine facies[1,4] and a characteristic elevated rim with central depression can be seen on the proximal interphalangeal joints ("doughnut sign"). Histologic examination of involved skin demonstrates fibroblast proliferation, fibrosis, and dermal deposition of mucin.[4] Systemic manifestations of SM are serious and have been fatal in some cases, secondary to mucin deposition in various organs. It may involve the cardiovascular, gastrointestinal, pulmonary, rheumatologic, and central nervous systems. Dysphagia is the most common extracutaneous manifestation of SM.[2,3] Up to 83% of cases have an associated paraproteinemia, predominantly an immunoglobulin G (IgG) lambda subtype, and a minority of these patients develop a plasma cell dyscrasia or multiple myeloma (10%).[1,2] Other associated diseases include Waldenstrom's macroglobulinemia as well as Hodgkin's and non-Hodgkin's lymphomas.[1,2]
Work-up, including serum protein electrophoresis, immunofixation electrophoresis, and measurement of immunoglobulin levels, is critical in all patients with suspected SM. Follow-up should be done at least every 6 months.[4] SM is characteristically quite resistant to therapy, although anecdotal reports attest to the efficacy of melphalan, thalidomide, and intravenous immunoglobulins (IVIG).[2,3] Autologous stem cell transplantation could be beneficial in some cases.[4,5]
Skin Therapy Letter. 2013;18(4) © 2013 SkinCareGuide.com
