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: Ans. is 'c' i.e. Parallel rays of tubular structure in lysosomeRef.: Robbin 6th/e p158, Oxford medicine 3rd/e p1927, Oxford Patho 5th/e p 1361First about PAS staining -PAS stain - It is a widely used stain to demonstrate polysaccharide in cells. So cells containing glycogen are strongly positive with PAS. However PAS also gives positive reaction with -GlycoproteinGlycolipidsProteoglycansNeutral mucinsNow, whether the PAS positivity of a particular cell is due to presence of glycogen or due to the presence of other substances can be determined by pretreatment with diastase.Diastase is an enzyme (an amylase) which digests glycogen. So 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. But if the cell is PAS positive due to presence of other substances mentioned, the cell will retain its PAS positivity even after pretreatment with diastase.So the presence of PAS positive and diastase resistant material in the cell indicates presence of one the following material in the cell. Glycoprotein, Glycolipids and neutral mucins.Now look at the clinical feature of the child.One year old boyHepatosplenomegalyDelayed milestonesThe above mentioned clinical features and likely presence of Glycolipids, Glycoprotein (PAS positive diastase resistant material) indicate some lysosomal storage disorder.Most probably it is a case of Niemann's picks diseaseSee the clinical features of Niemann Picks disease.Presence of hepatosplenomegalyMental retardationDelayed growthThe pathological feature of Niemann's Picks disease is characterized by the presence of large foam cells in bone marrow, liver and spleen.Electron microscopy will show pleomorphic inclusion, of lipids in Lysosomes. These lipids are enclosed in concentric or parallel lamellae.All the above mentioned features can be seen in Gaucher's disease too but the electron microscopy in Gaucher's is characterized by the presence of elongated distended Lysosomes containing the stored lipids in stacks of bilayers.
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