Acid sphingomyelinase deficiency: Epidemiologic and genetic aspects of a French cohort 1974-2021

Splenomegaly is the most common phenotype for Niemann-Pick disease type B (NPD-B), an autosomal recessive lipid storage disease caused by deficiency of the lysosomal enzyme acid sphingomyelinase. Although a spleen of massive volume is common in NPD-B, splenic rupture in this disease is rarely reported. We describe a patient with NPD-B who initially presented with spontaneous splenic rupture. Microscopic examination of the spleen specimen revealed expansion of the red pulp by abundant foamy histiocytes. A literature review revealed that splenic rupture resulting from latent splenomegaly may occur in middle adulthood in a mild form of NPD-B associated with SMPD1 variants of lower pathogenicity. We suggest that unexplained splenomegaly or splenic rupture should raise the possibility of a lysosomal storage disease, including NPD. For patients with NPD-B, spleen size should be evaluated periodically, and the risk of splenic rupture should always be considered.