Diagnosis of type A Niemann-Pick's disease by conjunctival biopsy.

Electron microscopic examination of the conjunctive of four children affected with Niemann-Pick's disease revealed a widespread storage process. The epithelium, the connective tissue cells, the endothelial cells and the pericytes of the capillaries are filled with lysosomal inclusions with pleomorphic structure. The nerve fibres show destructive process of the myelin sheaths and accumulation of lipid material in the Schwann cells. The extension of the lesions is similar, as shown by morphologic and morphometric analysis in early and terminal stages of the diseases. Conjunctival biopsy allows an early and secure diagnosis of Niemann-Pick's disease, and should be performed when the clinical symptoms suggest a lysosomal disorder.