Pathologic features of diabetic thick skin.

Skin thickening simulating scleroderma, or progressive systemic sclerosis, has previously been reported in children and adults with insulin-dependent diabetes mellitus. We have studied eighty-nine patients with insulin-dependent diabetes mellitus and twenty-five normal control subjects. Clinical evidence of skin thickening (diabetic thick skin) was found in 22% of patients with insulin-dependent diabetes mellitus and in 4% of control subjects (p less than 0.05). Full-thickness skin biopsy specimens were taken from the forearm of nine patients with insulin-dependent diabetes mellitus and diabetic thick skin, four patients with insulin-dependent diabetes mellitus and clinically normal skin, four patients with progressive systemic sclerosis, and four normal control subjects. The sections stained with hematoxylin and eosin showed increased thickness of the dermis of the forearm skin in all diabetic patients. In diabetic thick skin the collagen bundles were large, disorganized, and separated by clear spaces. Small amounts of acid mucopolysaccharides were present in the upper reticular dermis of five patients with diabetic thick skin. Electron microscopy of the dermis showed capillary basement membrane thickening in Groups 1, 2, and 3. All patients with diabetic thick skin showed active fibroblasts and extensive collagen polymerization in the rough endoplasmic reticulum. Occasional collagen flowers were noted in all patients with diabetic thick skin. Measurements of 100 collagen fibers in the upper and lower reticular dermis of each biopsy specimen showed predominance of large fibers (greater than 60 nm) in Groups 1 and 2. Unlike scleroderma, diabetic thick skin resulted in small fiber sizes (less than 60 nm) only rarely, and bimodality of fiber sizes was not seen.(ABSTRACT TRUNCATED AT 250 WORDS)