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Introduction: Lysosomal storage disorders (LSD) are characterized by the accumulation of partially degraded insoluble metabolites within lysosomes. GM1-gangliosidosis type 1 is a hereditary deficiency of lysosomal acid beta-galactosidase, particularly severe entity with marked central nervous system involvement. Facial dysmorphism, hepatosplenomegaly, and generalized skeletal dysplasia are usually present in infantile cases. Dermal melanocytosis encompasses a clinical spectrum of cutaneous diseases such as Mongolian spots among others. The association of dermal melanocytosis with LSD is uncommon and still poorly understood. We report here a case of dermal melanocytosis associated with GM1-gangliosidosis type 1. Patient: A 9-month-old caucasian boy referred for evaluation of severe generalized hypotonia, lethargy and developmental delay. Extensive and unusual blue macules resembling Mongolian spots with larger lesions distributed over posterior trunk and axilla were found. In addition to the skin lesions, the infant had coarse facial features with low nasal bridge, broad nose, long philtrum; gingival hypertrophy, hepatomegaly, bilateral hydrocele and lumbar cyphosis also were found. Blood count reveal vacuolated lymphocytes. Elevated urine oligosaccharides and beta galactosidase activity deficient confirm the diagnosis of GM1. Discussion: In the appropiate clinical setting, an unusual presentation of dermal melanocytosis may be a cutaneuos sign of an underlying LSD.

Dermal Melanocytosis; GM1-Gangliosidosis