Sixteen-year-old male, a known case of thalassaemia major since 5 years of age had massive splenomegaly. He was receiving 2 units of whole blood transfusion every month. Therapeutic splenectomy was performed.

Spleen weighed 700 gm. On cut surface it was tan colour and homogeneous. Histologically on Haematoxylin and Eosin stain, spleen showed few lymphoid follicles with dilated sinusoids packed with foamy histiocytes, which showed eccentric nucleus with abundant eosinophilic cytoplasm with crumpled silk appearance (Fig. 1). These cells were PAS positive and diastase resistant. Zeihl-Neilsen and GMS stains are negative for acid-fast bacilli and fungus respectively. Electron microscopy showed cells with eccentric nucleus and normal to degenerated mitochondria in the cytoplasm. Cytoplasm showed inclusion, which were fibrillary, surrounded by a single membrane (Figs. 2,3).

Storage cells in spleen are known to occur in Gaucher's disease.2 Ultrastructurally Gaucher's cells show cytoplasmic inclusion with smooth walled tubules. They have also been reported in various haematological conditions like thalassaemia major, chronic myeloid leukaemia, idiopathic thrombocytopenic purpura where they represent histiocytes that have phagocytosed erythrocytes, leucocytes or platelets respectively. Products of ingested cells accumulated in the cytoplasm of histiocytes due to absolute or relative insufficiency of catabolic enzymes resulting in incomplete metabolism.1

Sen Gupta et al have shown that the foamy appearance is due to accumulation of an acidic mucopolysaccharide due to the breakdown of immature erythroid cells in thalassaemia. Study of the incidence of the foamy cells in thalassaemia and other conditions indicate that the foam cells are demonstrable in varying numbers in almost all cases of thalassaemia.3 However, these cells were seen in large numbers in only 4 out of 30 cases studied.3 Ultra structurally these cells show cytoplasmic inclusion containing bundles of fine fibrils surrounded by single membrane similar to our case.

Fig. 1 : Section from spleen shows histiocytes with eccentric nuclei and abundant eosinophilic cytoplasm having crumpled silk appearance. (H and E, 20 X).

Zaino et al considered these histiocytes to be Gaucher's cells as spleen of one patient with thalassaemia contained slight increase in glucocerebroside.2 However, Beltrami et al do not support this view and have not found typical Gaucher's cells in the spleens of more than 150 thalassaemic patients studied by light microscopy.1 They believe that the ultra structure of storage cells observed in thalassaemia serves to distinguish them from the storage cells seen in Gaucher's disease.1

Figs. 2,3 : Electron microscopy - cytoplasmic inclusions containing fibrillar material surrounded by a single membrane (X 6000 and X 50 K).

We conclude that foamy histiocytes resembling Gaucher's cells may be seen in the reticulo-endothelial system in thalassaemia major. These storage cells result from incomplete catabolism of red cells especially their glycolipid rich membranes.2 These should not be mistaken for hereditary Gaucher's disease. Electron microscopy helps to distinguish these storage cells from those seen in hereditary Gaucher's disease.