Mucolipidosis II (I-cell disease): ultrastructural observations of conjunctiva and skin.

Conjunctival and skin biopsies from a 25-monih-old patient with mucolipidosis II (I-cell disease) were studied by electron microscopy. In both tissues the subepithelial connective tissue was markedly hypercellular, as histiocytes and fbroblasts showed extensive vacuolation by single membrane-limited inclusions with fbrillogranular and membranous lamellar contents. The Schwann cells and axonal processes of peripheral nerves and the vascular perithelial cells were similarly affected. Histochemical and ultrastructural evidence indicates that these storage vacuoles may be derived from lysosomes which contain excessive amounts of acid mucopolysaccharide and glycolipid. Biomicroscopically visible granularity of the corneal stroma suggests the accumulation of these storage substances also within the cornea. Symmetrically enlarged corneas were also present.