ABSTRACT
Niemann-Pick disease and beta-thalassemia are distinct conditions with specific clinical and morphological manifestations. Beta-thalassemia is the most common inherited blood disorder in Iran whereas Niemann-Pick disease, a lysosomal storage disorder, is rarely found in this country. This 5-month old girl, a known case of beta-thalassemia major was hospitalized for failure to thrive and hepathosplenomegaly. Because of unusual splenomegaly and liver enzymes disturbance that was not compatible with the first diagnosis, further evaluation revealed cherry red spot and high lipid profile suggestive of lysosomal storage disease. Foamy cells in the bone marrow and low activity of the specific enzyme led to the diagnosis of Niemann-Pick disease. This unique case illustrates the importance of looking for a second pathological condition in a patient whose clinical profile does not support the first diagnosis in its entirety