The stiff skin syndrome: case series, differential diagnosis of the stiff skin phenotype, and review of the literature.

BACKGROUND Stiff skin syndrome is a sclerodermalike disorder that presents in infancy or early childhood with rock-hard skin, limited joint mobility, and mild hypertrichosis in the absence of visceral or muscle involvement, immunologic abnormalities, or vascular hyperreactivity. OBSERVATIONS We describe 6 children who fit criteria for stiff skin syndrome. A review of the clinical range of this disorder and discussion of the differential diagnosis is presented. The age at onset in our cases ranged from infancy to 6 years of age. Stony-hard skin was noted mostly on the thighs, buttocks, and lower back with shoulder and arm involvement in 2 cases. There was associated hypertrichosis in 3 of 6 cases. Extracutaneous manifestations consisted primarily of joint restriction, and several patients had resulting postural and thoracic wall irregularities. Histopathologically, our cases showed areas of fascial sclerosis or showed increased fibroblast cellularity with thickened, sclerotic, horizontally oriented collagen bundles in the deep reticular dermis and/or subcutaneous septa without associated inflammation. CONCLUSIONS Stiff skin syndrome is characterized by an early, insidious onset of stony-hard skin, often with associated contracturelike joint restriction, hypertrichosis, and postural and thoracic wall abnormalities. Supportive histopathologic findings consisting of either fascial sclerosis or increased fibroblast cellularity with sclerotic collagen bundles in the deep reticular dermis and/or subcutaneous septa may help to confirm this diagnosis.