Hyalinosis cutis et mucosae. Defective digestion and storage of basal lamina glycoprotein synthesized by smooth muscle cells.

Electron microscopy revealed accumulation of fibrogranular materials associated with laminated basal lamina around the smooth muscle cells of tunica dartos (most strikingly) and of blood vessels, vascular endothelial cells, pericytes, myofibroblasts (not usual fibroblasts) as well as Schwann cells and perineuria. Around the presumably regressive and slightly shrunken sweat duct, a network of basal lamina containing fibrogranular materials was found in a configuration indicating that it would have surrounded the remnants of cells (involuted cells) of the sweat duct, probably consisting of old, undegradated, residual basal lamina. Consequently, it was suggested that hyalinosis cutis et mucosae might be caused by accumulation and invasion of basal lamina glycoprotein involving the type IV (plusV?) collagen into normal collagen fibers (bundles) due to defective degradation.