General Pathology Practice Questions

Q: CD56 is a marker of which cellular process?

Extrinsic pathway of apoptosis. **Explanation:** **CD95 (Fas Receptor)** is a crucial cell surface receptor that triggers the **Extrinsic Pathway of Apoptosis** (also known as the Death Receptor Pathway) [2]. When the Fas ligand (FasL) binds to the CD95 receptor, it leads to the formation of the Death-Inducing Signaling Complex (DISC), which activates **Caspase-8**, eventually leading to programmed cell death [2]. *Note: There appears to be a typographical error in the question stem provided; **CD95** is the marker for apoptosis, whereas **CD56** is typically the Neural Cell Adhesion Molecule (NCAM) used as a marker for Natural Killer (NK) cells and small cell carcinoma.* **Analysis of Options:** * **Option B (Correct):** The extrinsic pathway is initiated by external ligands binding to death receptors like CD95 (Fas) or TNF-R1 [3]. * **Option A (Incorrect):** The intrinsic (mitochondrial) pathway is triggered by internal cellular stress (DNA damage) and is regulated by the Bcl-2 family and the release of Cytochrome C, not by CD95/CD56 [1]. * **Option C (Incorrect):** Necrosis is an unprogrammed, accidental cell death characterized by cell swelling and membrane rupture; it does not involve specific signaling receptors like CD95. * **Option D (Incorrect):** Cellular adaptations (hypertrophy, hyperplasia, atrophy, metaplasia) are reversible changes in response to the environment, distinct from the programmed cell death pathways. **NEET-PG High-Yield Pearls:** * **Initiator Caspases:** Caspase-8 and 10 (Extrinsic); Caspase-9 (Intrinsic). * **Executioner Caspases:** Caspase-3, 6, and 7 (Common to both pathways). * **FLIP Protein:** Inhibits the extrinsic pathway by blocking Caspase-8 activation. * **CD56 Fact:** If the question specifically asks for CD56 in a neuroanatomy context, remember it is **NCAM**, vital for cell-cell adhesion and neurite outgrowth.

Q: Fontana-Masson stain primarily stains which type of granules in the cytoplasm?

Melanin. **Explanation:** The **Fontana-Masson stain** is a silver-based histochemical method used to identify substances with **argentaffin properties**. Argentaffin cells or granules have the inherent ability to reduce silver nitrate to metallic silver without the need for an external reducing agent, resulting in a black/dark brown deposit. **1. Why Melanin is Correct:** Melanin is a pigment produced by melanocytes [1]. It possesses strong reducing properties (argentaffin), allowing it to reduce the silver salts in the Fontana-Masson stain. This makes it the primary stain used to identify melanin in skin biopsies or to confirm the diagnosis of amelanotic melanomas. It also stains argentaffin granules in carcinoid tumors (neuroendocrine cells). **2. Why Incorrect Options are Wrong:** * **Copper (B):** Best visualized using **Rhodanine stain** or **Orcein stain** (commonly used in Wilson’s disease). * **Ferritin/Iron (C):** Identified using the **Perls’ Prussian Blue** reaction, which stains ferric iron bright blue. * **Hemoglobin (D):** Usually identified via its natural golden-brown color on H&E or specific immunohistochemistry; it does not have argentaffin properties. **NEET-PG High-Yield Pearls:** * **Argentaffin vs. Argyrophil:** Argentaffin cells (e.g., Melanin) reduce silver *spontaneously*. Argyrophil cells (e.g., certain neuroendocrine tumors) require an *external reducer* (like hydroquinone) to turn silver black. * **Other Melanin Stains:** **Schmorl’s reaction** (turns melanin blue-green) and **Masson-Fontana** (turns it black) [2]. * **DOPA reaction:** A biochemical test used to identify the enzyme tyrosinase in melanocytes. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 633-634. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, p. 1146.

Q: Which of the following processes involves caspase-1 and caspase-11 activation?

Pyroptosis. **Explanation:** **Pyroptosis** is a specialized form of programmed cell death characterized by the release of pro-inflammatory cytokines and cell swelling [1]. It is triggered by the activation of **inflammasomes** [2]. * **Mechanism:** Cytosolic sensors (like NLRP3) detect microbial products or danger signals, leading to the activation of **Caspase-1** (canonical pathway) [1][2]. In the non-canonical pathway, **Caspase-11** (in mice) or **Caspase-4/5** (in humans) directly sense bacterial LPS [1]. * **Execution:** These caspases cleave **Gasdermin D**, which forms pores in the plasma membrane, causing osmotic lysis and the release of IL-1β and IL-18. **Why other options are incorrect:** * **Necrosis:** This is an accidental, unregulated cell death resulting from severe injury (e.g., ischemia). It does not involve specific caspase activation. * **Necroptosis:** While it is "programmed" necrosis, it is **caspase-independent** [1]. It relies on the RIPK1-RIPK3-MLKL signaling complex [1]. * **Apoptosis:** This is "silent" programmed cell death. It involves **Caspase-3, 6, and 7** (executioners) and **Caspase-8 and 9** (initiators), but specifically excludes the inflammatory caspases (1 and 11). **High-Yield Pearls for NEET-PG:** * **Caspase-1** is also known as Interleukin-1 Converting Enzyme (ICE). * **Gasdermin D** is the definitive "pore-forming" protein in pyroptosis. * Unlike apoptosis, pyroptosis is **pro-inflammatory** and results in membrane rupture [1]. * **Ferroptosis** (another high-yield topic) is iron-dependent lipid peroxidation and is also caspase-independent. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Cellular Responses to Stress and Toxic Insults: Adaptation, Injury, and Death, p. 71. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, p. 196.

Question 1

Fibrinoid necrosis is seen in all of the following except:

Accepted Answer

Diabetes mellitus

Answer

Polyarteritis nodosa (PAN)

Answer

Malignant hypertension

Answer

Systemic lupus erythematosus (SLE)

Question 2

If a parent is heterozygous and the other parent is homozygous for an autosomal-recessive gene, what will be the genetic outcome for their children?

Accepted Answer

50% of children will be affected, and the rest will be carriers.

Answer

75% of children will be affected.

Answer

No child will be affected, but all will be carriers.

Answer

25% of children will be affected, and the rest will be carriers.

Question 3

Which anatomical site is least commonly affected by air embolism?

Accepted Answer

Liver

Answer

Kidney

Answer

Heart

Answer

Brain

Question 4

A 55-year-old male presents with severe chest pain radiating to the left arm. ECG shows ST segment elevation in the V4, V5, and V6 leads. CK-MB and troponin levels are found to be increased. What is the most likely cause for the increase in serum enzymes?

Accepted Answer

Cell membrane defects

Answer

Clumping of nuclear chromatin

Answer

Lysosomal Autophagy

Answer

Mitochondrial swelling

Question 5

Pyknosis is characterized by

Accepted Answer

Nuclear shrinkage

Answer

Nuclear basophilia

Answer

Nucleus disintegration

Answer

Nucleolus disintegration

Question 6

CD56 is a marker of which cellular process?

Accepted Answer

Extrinsic pathway of apoptosis

Answer

Intrinsic pathway of apoptosis

Answer

Necrosis of cell

Answer

Cellular adaptation

Question 7

Fontana-Masson stain primarily stains which type of granules in the cytoplasm?

Accepted Answer

Melanin

Answer

Copper

Answer

Ferritin

Answer

Hemoglobin

Question 8

Which of the following cells are involved in the process of efferocytosis?

Accepted Answer

Macrophages

Answer

T lymphocytes

Answer

B lymphocytes

Answer

NK cells

Question 9

Which of the following processes involves caspase-1 and caspase-11 activation?

Accepted Answer

Pyroptosis

Answer

Necrosis

Answer

Necroptosis

Answer

Apoptosis

Question 10

A one-year-old boy presented with hepatosplenomegaly and delayed milestones. The liver biopsy and bone marrow biopsy revealed the presence of histiocytes with PAS-positive cytoplasm. Electron microscopic examination of these histiocytes is most likely to reveal which of the following?

Accepted Answer

Parallel tubular aggregates in lysosomes

Answer

Birbeck granules in the cytoplasm

Answer

Myelin figures in the cytoplasm

Answer

Electron-dense deposits in the mitochondria

General Pathology — MCQs

General Pathology — MCQs

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