Ultrastructural studies of the skin and cultured fibroblasts in I-cell disease.

The skin and cultured fibroblasts from a patient with I-cell disease were examined by electron microscopy. Multiple vacuolations were seen in fibroblast and/or histiocyte-like cells, secretory cells of eccrine glands, and Schwann cells of the skin. Vacuolar inclusions were single membrane-limited, and contained a few reticulo-floccular and vesicular materials, endothelial cells of the dermal capillaries contained other types of inclusions, which were also membrane-limited, more electron dense, and multivesicular. The epidermis and pilosebaceous appendages seemed to be normal. Cultured skin fibroblasts contained prominent inclusions which varied in size and morphology. Acid phosphatase activity was seen in some of those inclusions, indicating their derivation from lysosomes. These findings suggest that the I-cell disease is a type of lysosomal storage disease and that electron microscopic examination of normal-appearing skin in this disease may contribute to the diagnosis.