Mucolipidosis IV. Histopathology of conjunctiva, cornea, and skin.

The condition of a 4-year-old white girl of Ashkenazi Jewish parents was diagnosed as mucolipidosis IV on the basis of marked corneal clouding and severe psychomotor retardation, in the absence of facial-skeletal dysplasia or abnormal mucopolysacchariduria. The results of histochemical and ultrastructural studies of conjunctiva, skin, and corneal epithelium confirmed the combined storage of acid mucopolysaccharide and complex lipid substances. An unusual histopathologic feature of mucolipidosis IV is the predisposition of extreme storage involvement of corneal epithelial cells with relative sparing of the keratocytes, which is a finding of potential therapeutic implication. In addition, application of electron microscopic study of cultured amniotic cells and conjunctival biopsy specimens to assess for the parents the mother's subsequent pregnancy additional emphasizes the value of ultrastructural studies in the diagnosis of lysosomal storage disease.