Congenital deficiency in lysosomal sphingomyelinase, which results in sphingomyelin, cholesterol and glycolipid accumulation in macrophages in liver, spleen, bone marrow, hepatocytes and CNS cells.
Pancytopenia caused by suppression of hematopoiesis in the marrow. Other symptoms vary, depending on other affected organs.
Bone marrow is hypercellular with suppressed hematopoiesis and an increased number of large macrophages, which have eccentric nuclei and abundant foamy cytoplasm.