Scleromyxedema is a sclerotic variant of papular mucinosis, in which lichenoid papules and scleroderma-like features are present. We describe a patient with scleromyxedema with IgG type lambda chain paraprotein, a systemic sclerosis-like illness, and myositis. The patient's serum contained Scl 70 antibodies, characteristic of scleroderma. Electromyography showed signs of acute myositis and the creatine phosphokinase (CPK) level was elevated. Multiply passaged fibroblasts from the patient's skin lesions showed altered growth response in vitro. The patient was treated with cyclosporin (4 mg/kg/day) with improvement.