A one year old boy presented with hepatosplenomegaly and delayed milestones. The liver biopsy and bone marrow biopsy revealed presence of histiocytes with PAS-positive Diastase-resistant material in the cytoplasm. Electron-microscopic examination of these histiocytes is most likely to reveal the presence of:
Correct Answer: Parallel rays of tubular structures in lysosomes
Description: PAS stain is a widely used stain which gives positive reaction with glycogen (primarily) and non glycogen substances like glycoprotein, glycolipids, proteoglycans and neutral mucins. Whether the PAS positivity of a paicular cell is due to presence of glycogen or due to latter can be differentiated with diastase (glycogen digesting enzyme). If the cell is PAS positive due to glycogen, the pretreatment with diastase will make it PAS negative. But if the cell is PAS positive due to non glycogen substances, the cell will retain its PAS positivity even after pretreatment with diastase. So, in the given question, the presence of PAS positive and diastase resistant material indicates presence of non glycogen substances. * The clinical feature of delayed milestones and hepatosplenomegaly in 1 year old boy is suggestive of some lysosomal storage disorder (like Niemann Picks disease). * This disease is characterized by the presence of large foam cells in bone marrow, liver and spleen. There is presence of pleomorphic inclusion of lipids in lysosomes enclosed in concentric or parallel lamellae.
Category:
Pathology
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