Histochemical characterization of the cutaneous involvement of acromegaly.

We evaluated the pathogenesis of skin thickening in three patients with acromegaly. Growth hormone levels were normal in one patient and were elevated in two patients. Skin biopsy specimens were obtained from the forearm. Hematoxylineosin staining showed slight epidermal thinning and, in two of the patients, a small increase in the number of fibroblasts. Selective stains for collagen, elastic, and reticular fibers disclosed normal connective tissue. The most striking abnormality was increased glycosaminoglycan deposition on the slides stained with colloidal iron. Glycosaminoglycan infiltration occurred mostly in the papillary and upper reticular dermis and was not directly related to the simultaneous growth hormone levels. Tissue digestion with specific enzymes identified hyaluronic acid, chondroitin-4- and 6-sulfate, and dermatan sulfate as the most prominent glycosaminoglycans in the dermis. The skin ultrastructure appeared to be preserved on electron microscopy. We conclude that cutaneous mucinoses is the main cause for the thickening of the skin in acromegaly.