Niemann-Pick Disease with the Type B phenotype is based on a moderate-to-severe deficiency in acid sphingomyelinase, which results in accumulation of sphingomyelin and other lipids within lysosomes of monocytes and macrophages.


Inheritance: autosomal recessive


Clinical features:

(1) normal pregnancy and delivery

(2) onset of illness during infancy or childhood

(3) hepatosplenomegaly, resulting in a protuberant abdomen

(4) chest X-rays show a diffuse reticular or finely nodular pulmonary infiltrate

(5) mild to severe respiratory disease which can progress to cor pulmonale

(6) usually no deterioration in intellect or neurologic status

(7) rare patients may show cerebellar ataxia

(8) a few patients may have a cherry red or gray granular macula

(9) occasional patients may have pancytopenia secondary to hypersplenism

(10) patients may develop cirrhosis with ascites


Laboratory findings

(1) acid sphingmyelinase activity < 10%

(2) lipid-laden foam cells (Niemann-Pick Disease or NPD cells) in bone marrow or liver biopsy


Course: death occurs from childhood to adulthood


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