Ultrastructural findings of rectal and skin biopsies in adult GM1-gangliosidosis.

We report the ultrastructural findings in rectal and skin biopsies in four cases with adult GM1-gangliosidosis. The rectal specimens taken under endoscopic control contained submucosal plexuses, which were easily identified on light-microscopic and electron-microscopic examination. In all cases the ganglion cells in submucosal plexus contained characteristic osmiophilic lamellar inclusions, some of which were typical membranous cytoplasmic bodies, were commonly observed in the ganglion cells, Schwann's cells, vascular endothelial cells, and perithelial cells in rectal biopsy, and membrane-bound clear vacuoles were occasionally seen in the cytoplasm of rectal and cutaneous fibroblasts. However, the axons of unmyelinated nerves in both biopsies showed a normal appearance, and there was no significant change in the eccrine glands in skin biopsy. Comparing rectal and skin biopsies, the former was found to be more valuable for morphological diagnosis of this disease, and our ultrastructural examination of rectal biopsy revealed that enteric nerve cells were involved even in adult GM1-gangliosidosis with a benign course and restricted cerebral lesions.