Dermal melanocytosis as a sign of GM1 gangliosidosis.

Abstract

GM1 gangliosidosis is an autosomal recessive hereditary disease resulting from deficiency of the enzyme β-galactosidase, which leads to massive accumulation of GM1 gangliosides in various tissues. Dermal melanocytosis is the persistence of dendritic melanocytes in the dermis: usually present as a Mongolian spot in the sacral region, it tends to spontaneously regress. A very extensive dermal melanocytosis both in the dorsal and ventral region and in the limbs, persistent and with an extensive tendency, is sometimes associated with gangliosidosis and can be a revealing sign of the disease. We describe the case of a 7-month-old girl in whom extensive dermal melanocytosis led to the early diagnosis of GM1 gangliosidosis.