General Pathology Practice Questions

Q: Oil Red O staining is used for which type of specimen preparation?

Frozen section. **Explanation:** **1. Why Frozen Section is Correct:** Oil Red O is a lysochrome (fat-soluble) dye used to demonstrate **neutral lipids and triglycerides**. The fundamental principle of lipid staining is that the dye must be more soluble in the lipid than in its solvent. In routine histological processing (paraffin embedding), specimens undergo dehydration with **alcohol** and clearing with **xylene**. These organic solvents dissolve lipids, leaving behind empty vacuoles (as seen in adipocytes). To preserve lipids within the tissue, the specimen must bypass these solvents. **Frozen sections** (using a cryostat) are the gold standard because they maintain the chemical integrity of lipids, allowing the Oil Red O to physically dissolve into the fat droplets, staining them bright red. **2. Why Other Options are Incorrect:** * **Alcohol & Formalin fixed specimens (C & D):** While formalin itself does not dissolve lipids, the subsequent processing steps required for paraffin embedding (dehydration via graded alcohols and clearing agents) remove the lipids entirely. * **Glutaraldehyde fixed specimen (B):** This is primarily used for Electron Microscopy to provide superior protein cross-linking but does not prevent lipid loss during the routine dehydration required for light microscopy. **High-Yield Clinical Pearls for NEET-PG:** * **Sudan Black B:** Another common lipid stain; it is more sensitive for phospholipids and myelin. * **Clinical Application:** Oil Red O is used to diagnose **Fat Embolism Syndrome** (in lung/kidney biopsies) and to identify lipid-rich tumors like liposarcomas or xanthomas. * **Osmium Tetroxide:** The only fixative that also acts as a stain for lipids, turning them black (used in EM). * **Mounting:** Always use **aqueous mounting media** (e.g., glycerin jelly) for lipid stains, as organic mounting media will dissolve the stain.

Q: Which of the following can be stained using the technique shown?

Collagen. ***Collagen*** - **Masson's Trichrome staining** specifically highlights **collagen fibers** in blue or green color, making it the primary target structure. - This technique is widely used to assess **fibrosis** and **connective tissue** distribution in pathological specimens. *Bone* - Bone tissue requires **decalcification** before routine staining and is better visualized with **von Kossa** or **alizarin red** stains. - **Masson's Trichrome** does not effectively demonstrate **mineralized bone matrix** or **osteoid**. *Skin tissue* - While skin contains collagen that can be stained, **skin tissue** as a whole is not the specific target of this technique. - **Masson's Trichrome** stains the **collagen component** within skin, not the entire skin structure itself. *Cartilage* - Cartilage matrix is primarily composed of **proteoglycans** and **chondroitin sulfate**, not collagen fibers. - **Alcian blue** or **safranin O** are preferred stains for demonstrating **cartilage matrix** and **glycosaminoglycans**.

Question 1

An elderly male's autopsy reveals brown atrophy of the liver. Microscopic examination shows a finely granular, yellow-brown pigment that frequently encircles the nucleus. Brown atrophy is attributed to the accumulation of which substance?

Accepted Answer

Lipofuscin

Answer

Melanin

Answer

Hemosiderin

Answer

Hematin

Question 2

What is the cause for caseous necrosis in Tuberculosis?

Accepted Answer

High lipid content

Answer

Hydrolytic enzymes

Answer

Mycolic acid

Answer

Hydrophobic changes by the bacterial wall

Question 3

All of the following are methods of cellular adaptation EXCEPT?

Accepted Answer

Dysplasia

Answer

Atrophy

Answer

Hyperplasia

Answer

Hypertrophy

Question 4

In apoptosis, permeabilization of which membrane occurs?

Accepted Answer

Mitochondrial membrane

Answer

Nuclear membrane

Answer

Cytoplasmic membrane

Answer

Lysosome

Question 5

Which cation is found in extremely high concentrations in cells that have undergone coagulative necrosis?

Accepted Answer

Calcium

Answer

Potassium

Answer

Iron

Answer

Cobalt

Question 6

Annexin V is a marker of?

Accepted Answer

Apoptosis

Answer

Necrosis

Answer

Gangrene

Answer

Aging

Question 7

Oil Red O staining is used for which type of specimen preparation?

Accepted Answer

Frozen section

Answer

Glutaraldehyde fixed specimen

Answer

Alcohol fixed specimen

Answer

Formalin fixed specimen

Question 8

DNA integrity and replication are ensured at which stage of the cell cycle?

Accepted Answer

End of G2

Answer

End of M

Answer

End of G1

Answer

End of S

Question 9

Which of the following is a characteristic of classical Mendelian inheritance of an autosomal dominant disease?

Accepted Answer

Variable expressivity

Answer

Complete penetrance

Answer

Affected individuals have unaffected parents

Answer

Very early onset in life

Question 10

Which of the following can be stained using the technique shown?

Accepted Answer

Collagen

Answer

Bone

Answer

Skin tissue

Answer

Cartilage

General Pathology — MCQs

General Pathology — MCQs

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