Angiokeratoma corporis diffusum associated with beta-mannosidase deficiency.

BACKGROUND: Angiokeratoma corporis diffusum (ACD) was at one time thought to be synonymous with Anderson-Fabry disease. However, it is well known that widespread angiokeratomas may also be found in other lysosomal enzyme disorders, as well as in patients with normal enzyme activities. beta-Mannosidase deficiency was first described in humans in 1986; since then, only 11 cases of beta-mannosidase deficiency, which occurred in 8 families, have been reported. Although the clinical manifestations are varied, mental retardation and neurologic disorders are present in practically all patients. OBSERVATIONS: We describe a 22-year-old woman who, since the age of 12 years, presented with progressive ACD affecting the lower limbs and the buttocks. Enzymatic studies revealed beta-mannosidase deficiency in cultured fibroblasts and in samples of serum and leukocytes. The patients's parents in turn exhibited intermediate enzyme levels, thus confirming the recessive autosomal hereditary nature of the disease. With the exception of an introverted character, the patient demonstrated no other anomalies.
CONCLUSIONS: This is the first case of beta-mannosidase deficiency diagnosed as a result of purely dermatologic findings, in the form of ACD. beta-Mannosidase deficiency should therefore be included when screening for enzyme abnormalities in patients with ACD, even in the absence of neurologic disorders or mental retardation.