General Pathology Practice Questions

Q: The given pedigree chart most appropriately resembles which of the following diseases?

Duchenne's muscular dystrophy. ***Duchenne's muscular dystrophy*** - Exhibits classic **X-linked recessive inheritance** pattern with affected males, unaffected carrier females, and **no male-to-male transmission**. - The **dystrophin gene** mutation on the X chromosome causes progressive muscle weakness primarily in boys, matching the pedigree pattern. *Rett syndrome* - Follows **X-linked dominant inheritance** with affected females and is typically **lethal in males**. - Shows a different pattern where affected mothers can pass the condition to both male and female offspring. *Albinism* - Demonstrates **autosomal recessive inheritance** affecting both males and females equally when both parents are carriers. - Would show horizontal pattern in siblings rather than the **vertical male-predominant** pattern seen in X-linked conditions. *Marfan syndrome* - Follows **autosomal dominant inheritance** with **vertical transmission** through generations affecting both sexes equally. - Shows **50% risk** to offspring regardless of gender, unlike the sex-linked pattern in the pedigree.

Q: Which stain is used for melanin?

Masson Fontana stain. **Explanation:** **Masson Fontana stain** is the correct answer because it is a silver-based stain used to identify **melanin** and argentaffin granules. The underlying principle is the **argentaffin reaction**: melanin is a reducing agent that can reduce silver nitrate to metallic silver without the need for an external reducing agent, resulting in a black/brown deposit. **Analysis of Incorrect Options:** * **Oil Red O (Option A):** This is a fat-soluble dye used to demonstrate **neutral lipids and triglycerides** in frozen sections. It is not used for pigments like melanin. * **Gomori Methenamine Silver (GMS) (Option B):** While also a silver stain, it is primarily used to highlight **fungal cell walls** (e.g., *Pneumocystis jirovecii*) and certain bacteria. * **Periodic Acid-Schiff (PAS) (Option C):** This stain detects **glycogen, mucopolysaccharides, and basement membranes**. It is classically used for diagnosing clear cell carcinomas or fungal infections. **NEET-PG High-Yield Pearls:** 1. **Bleaching Test:** Melanin can be confirmed by "bleaching" it with strong oxidizing agents like hydrogen peroxide or potassium permanganate. If the pigment disappears, it is confirmed as melanin. 2. **Differentiating Pigments:** To distinguish melanin from **Hemosiderin**, use **Prussian Blue (Perl’s stain)**; melanin will be negative, while hemosiderin will turn blue. 3. **IHC Marker:** For malignant melanoma, **S-100** is sensitive, but **HMB-45** and **Melan-A** are more specific immunohistochemical markers.

Q: Which is the most common complement protein deficiency?

C2. **Explanation:** The complement system is a vital component of innate immunity. Among all the inherited complement deficiencies, **C2 deficiency** is the most common (Option B). **Why C2 is the correct answer:** C2 deficiency is an autosomal recessive condition and is the most frequently reported complement protein defect in Western populations. It is often associated with an increased risk of autoimmune diseases, particularly **Systemic Lupus Erythematosus (SLE)**, because C2 is essential for the classical pathway's role in clearing immune complexes. Interestingly, many individuals with C2 deficiency remain asymptomatic because the alternative pathway remains intact to handle bacterial pathogens. **Analysis of Incorrect Options:** * **C1 (Option A):** Deficiency of C1 (C1q, C1r, or C1s) is rare. It is most strongly associated with the development of SLE (over 90% of C1q-deficient individuals develop SLE). [1] * **C3 (Option C):** C3 is the central molecule for all three complement pathways. While not the most common, it is the **most severe** deficiency. Patients present with recurrent, life-threatening pyogenic bacterial infections (e.g., *S. pneumoniae*) and Type III hypersensitivity reactions. * **C4 (Option D):** C4 deficiency is also associated with SLE-like syndromes but is less common than C2 deficiency. **NEET-PG High-Yield Pearls:** 1. **Most common deficiency:** C2. 2. **Most severe deficiency:** C3. 3. **C1 esterase inhibitor deficiency:** Leads to **Hereditary Angioedema** (characterized by low C4 levels). 4. **C5-C9 (MAC) deficiency:** Increases susceptibility to **Neisseria** infections (meningitis and gonorrhea). 5. **CH50 Assay:** Used to screen the classical pathway; it will be low/zero in C1-C8 deficiencies. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, p. 228.

Question 1

All of the following are stress sensors/regulators for apoptosis, except?

Accepted Answer

BAX

Answer

Puma

Answer

Noxa

Answer

BiM

Question 2

The given pedigree chart most appropriately resembles which of the following diseases?

Accepted Answer

Duchenne's muscular dystrophy

Answer

Rett syndrome

Answer

Albinism

Answer

Marfan syndrome

Question 3

When should EDTA be added to a blood sample?

Accepted Answer

EDTA is added to the test tube before blood collection.

Answer

Administered orally several days prior to blood collection.

Answer

Administered intravenously before drawing blood.

Answer

EDTA is not an anticoagulant.

Question 4

Which immunoglobulin is primarily found in mucosal secretions?

Accepted Answer

IgA

Answer

IgG

Answer

IgM

Answer

IgD

Question 5

Which stain is used for melanin?

Accepted Answer

Masson Fontana stain

Answer

Oil red O stain

Answer

Gomori methenamine silver stain

Answer

Periodic acid-Schiff stain

Question 6

Which is the most common complement protein deficiency?

Accepted Answer

C2

Answer

C1

Answer

C3

Answer

C4

Question 7

Which of the following statements regarding the Human Leukocyte Antigen (HLA) complex is incorrect?

Accepted Answer

Class-I molecules are homodimers, whereas Class-II molecules are heterodimers.

Answer

Class-I antigens are expressed in all nucleated cells and platelets.

Answer

Class-II molecules are involved in the induction of helper T-cells.

Answer

Class-I molecules are involved in the induction of cytotoxic T-cells.

Question 8

Which of the following conditions is associated with coagulative necrosis?

Accepted Answer

Tuberculosis

Answer

Sarcoidosis

Answer

Cryptococcal infection

Answer

Gangrene

Question 9

Which of the following is characteristic of irreversible cell injury?

Accepted Answer

Mitochondrial densities

Answer

Cellular swelling

Answer

Blebs

Answer

None of the above

Question 10

Which gene is involved in endometrial carcinoma?

Accepted Answer

PTEN

Answer

BRAF

Answer

KRAS

Answer

Mismatch repair genes

General Pathology — MCQs

General Pathology — MCQs

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