Adult Niemann-Pick disease masquerading as sea blue histiocyte syndrome: report of a case confirmed by lipid analysis and enzyme assays.

We present the clinical, pathologic, and metabolic findings of an adult woman with debilitating coronary artery disease and hepatosplenomegaly who was discovered to have multiorgan infiltration by sea blue histiocytes. A diagnosis of sea blue histiocyte (SBH) syndrome was made and no further workup performed. The patient suffered from progressive heart failure and sepsis following coronary artery bypass surgery and died 9 months after presentation. Tissues examined at autopsy showed pronounced infiltrates of both granular sea blue histiocytes and foamy, vacuolated histiocytes, which were morphologically compatible with Niemann-Pick cells. Ultrastructural examination of these cells revealed lamellar myelin-like figures as described in Niemann-Pick (N-P) disease. Fibroblast enzyme assay studies and liver lipid analyses performed after the patient's death revealed pronounced sphingomyelinase deficiency and a lipid profile diagnostic of N-P disease, type B. This case adds further support to the claim that some cases of apparent SBH syndrome actually represent a type of N-P disease.