General Pathology Practice Questions

Q: Which stain is used for melanin?

Masson Fontana stain. **Explanation:** The correct answer is **Masson Fontana stain**. **1. Why Masson Fontana is correct:** Melanin is a non-lipid, non-hematogenous pigment produced by melanocytes [1]. It possesses **argentaffin** properties, meaning it has the inherent ability to reduce silver nitrate to metallic silver without the need for an external reducing agent. The Masson Fontana stain utilizes this property; the silver salts are reduced by melanin, resulting in a distinct **black** coloration of the pigment granules. **2. Analysis of Incorrect Options:** * **Alizarin red S:** This is a specialized stain used to identify **calcium** deposits. It reacts with calcium to form an orange-red lake. * **Von Kossa:** This is another method for **calcium** (specifically phosphates and carbonates). It is a metal substitution method where silver replaces calcium, appearing as black deposits. * **PAS (Periodic Acid-Schiff) stain:** This stain is primarily used to demonstrate **glycogen, mucopolysaccharides, and basement membranes**. It stains these structures magenta/bright pink. It is also the stain of choice for identifying fungal cell walls. **3. NEET-PG High-Yield Pearls:** * **Bleaching Test:** To confirm a pigment is melanin, "Melanin Bleaching" is performed using hydrogen peroxide or potassium permanganate. Melanin disappears, whereas other pigments like lipofuscin do not. * **Schmorl’s Reaction:** Another method used for melanin (and lipofuscin), which produces a blue-green color. * **DOPA Reaction:** Used to identify the enzyme tyrosinase in fresh tissue to confirm melanocytic activity. * **Iron Stain:** To differentiate melanin from hemosiderin (which looks similar), use **Prussian Blue (Perl’s stain)**; it stains hemosiderin blue but does not react with melanin. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 633-634.

Q: Deficiency of which of the following factors increases the incidence of thrombus formation?

Lipoprotein A. **Explanation** The question asks which **deficiency** increases the incidence of thrombus formation. This is a classic "except" style logic trap common in NEET-PG. **1. Why Lipoprotein (a) is the Correct Answer:** Unlike the other options, **Lipoprotein (a) [Lp(a)]** is a pro-thrombotic and pro-atherogenic factor. Therefore, its **elevation** (excess), not its deficiency, leads to thrombosis. A **deficiency** of Lp(a) would actually be cardioprotective and decrease the risk of thrombus formation. In the context of this specific question, it is the "odd one out" because the other three factors are natural anticoagulants whose deficiency causes a hypercoagulable state. **2. Analysis of Incorrect Options (Natural Anticoagulants):** * **Protein C & Protein S:** These are Vitamin K-dependent proteins. Protein C (activated by thrombomodulin) inactivates Factors Va and VIIIa, with Protein S acting as its cofactor. A **deficiency** in either leads to unchecked coagulation and venous thromboembolism (VTE). * **Antithrombin III (ATIII):** This is the most potent natural inhibitor of thrombin (IIa) and Factor Xa. **Deficiency** of ATIII leads to severe hypercoagulability and is clinically significant because it causes **heparin resistance**. **3. Clinical Pearls for NEET-PG:** * **Lp(a) Mechanism:** It is structurally similar to plasminogen; it competes for binding sites, thereby inhibiting fibrinolysis and promoting clot stability. * **Warfarin-Induced Skin Necrosis:** This occurs in patients with **Protein C deficiency** when starting Warfarin without a heparin bridge (due to the short half-life of Protein C). * **Most Common Inherited Thrombophilia:** Factor V Leiden (resistance to Activated Protein C). * **Antithrombin III Deficiency:** Suspect this if a patient’s PTT fails to prolong despite therapeutic doses of Heparin.

Q: Enzymatic degradation of chromatin by endonucleases is referred to as:

Karyolysis. ### Explanation The hallmark of irreversible cell injury and cell death is nuclear change [1]. These changes occur in a sequential or distinct manner depending on the type of necrosis. **Why Karyolysis is Correct:** **Karyolysis** refers to the fading of the basophilia of chromatin. This process is driven by the **enzymatic degradation of DNA by endonucleases** (specifically DNase) released from lysosomes. As the DNA is hydrolyzed, the nucleus loses its staining intensity and eventually disappears completely within 1 to 2 days. **Analysis of Incorrect Options:** * **B. Pyknosis:** This is characterized by **nuclear shrinkage** and increased basophilia. The DNA condenses into a solid, shrunken, dark mass. It is the first stage of nuclear morphology changes in cell death [1]. * **C. Karyorrhexis:** This follows pyknosis. The pyknotic nucleus undergoes **fragmentation** (rupture of the nuclear membrane), breaking into multiple small, dense "nuclear dust" particles [1]. **High-Yield NEET-PG Pearls:** * **Sequence of Nuclear Changes:** Pyknosis (Condensation) → Karyorrhexis (Fragmentation) → Karyolysis (Dissolution). * **Apoptosis vs. Necrosis:** While karyolysis is a classic feature of **necrosis**, the characteristic nuclear change in **apoptosis** is internucleosomal DNA fragmentation (forming a "ladder" pattern on electrophoresis), but the nucleus typically fragments into membrane-bound apoptotic bodies without complete enzymatic dissolution (karyolysis) in the same manner. * **Basophilia:** Loss of basophilia in karyolysis is due to the loss of DNA, which is the acidic component that binds basic dyes like Hematoxylin. **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. 53.

Question 1

Amyloid material can be best diagnosed by which method?

Accepted Answer

Polarized microscopy

Answer

Electron microscopy

Answer

X-ray crystallography

Answer

Scanning electron microscopy

Question 2

Yellow or green pigmentation of teeth is seen in which of the following conditions?

Accepted Answer

Erythroblastosis fetalis

Answer

Porphyria

Answer

Internal resorption

Answer

Nasmyth membrane

Question 3

Which stain is used for melanin?

Accepted Answer

Masson Fontana stain

Answer

Alizarin red S

Answer

Von Kossa

Answer

PAS stain

Question 4

Peripheral edema in congestive cardiac failure (CCF) is primarily due to which of the following mechanisms?

Accepted Answer

Increased hydrostatic pressure

Answer

Increased sympathetic tone

Answer

Atrial natriuretic peptide (ANP) release

Answer

Pulmonary hypertension

Question 5

Virchow's triad includes all except which of the following?

Accepted Answer

Intimal tear

Answer

Vessel wall endothelial injury

Answer

Thrombus formation

Answer

Local blood stasis

Question 6

Secondary amyloidosis is seen most commonly in which of the following conditions?

Accepted Answer

Tuberculosis

Answer

Actinomycosis

Answer

Rabies

Answer

Secondary syphilis

Question 7

Which of the following conditions can present with numbness of the lip in the absence of previous dental treatment?

Accepted Answer

Metastatic carcinoma

Answer

Central nervous system lesion

Answer

Osteomyelitis

Answer

Infection

Question 8

Deficiency of which of the following factors increases the incidence of thrombus formation?

Accepted Answer

Lipoprotein A

Answer

Protein C

Answer

Antithrombin III

Answer

Protein S

Question 9

Which of the following diseases is transmitted as an X-linked inheritance?

Accepted Answer

Alport syndrome

Answer

Phenylketonuria

Answer

Myotonic dystrophy

Answer

Spinal muscular atrophy

Question 10

Enzymatic degradation of chromatin by endonucleases is referred to as:

Accepted Answer

Karyolysis

Answer

Pyknosis

Answer

Karyorrhexis

Answer

None of the above

General Pathology — MCQs

General Pathology — MCQs

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