General Pathology Practice Questions

Q: What is the most common fixative used in pathology?

Formaldehyde. **Explanation:** **Formaldehyde (Option C)** is the most commonly used fixative in histopathology. It is typically used as **10% Neutral Buffered Formalin (NBF)**. It works by creating cross-links between proteins (specifically forming methylene bridges), which preserves the tissue architecture and prevents autolysis and putrefaction. Its popularity stems from its low cost, ease of preparation, and the fact that it allows for a wide range of subsequent staining techniques, including H&E and Immunohistochemistry (IHC). **Analysis of Incorrect Options:** * **Glutaraldehyde (Option A):** This is the fixative of choice for **Electron Microscopy**. It provides superior preservation of ultrastructural details but penetrates tissue very slowly and makes it too brittle for routine light microscopy. * **Alcohol (Option B):** Ethanol or methanol are "dehydrating" fixatives. They are primarily used for **cytological smears** (e.g., Pap smears) because they preserve nuclear detail well, but they cause significant tissue shrinkage. * **Picric acid (Option D):** Found in **Bouin’s fluid**, it is excellent for preserving glycogen and delicate morphology (like testicular or intestinal biopsies) but can cause significant tissue hardening and yellow discoloration. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Formaldehyde acts by **cross-linking of proteins**. * **Concentration:** 10% Formalin is actually a 4% solution of formaldehyde gas in water. * **Best for EM:** Glutaraldehyde. * **Best for Lipids:** Frozen section (Formalin dissolves lipids during processing). * **Best for Enzyme Histochemistry:** Cold acetone or frozen sections. * **Carnoy’s Fluid:** A rapid fixative used for urgent biopsies and preserving nucleic acids.

Q: Which of the following conditions is due to a defect in the normal keratinization of the oral mucosa?

White sponge nevus. **Explanation:** **White Sponge Nevus (WSN)** is the correct answer because it is a rare, autosomal dominant hereditary condition caused by mutations in the genes encoding **Keratin 4 and Keratin 13**. These keratins are specifically expressed in the suprabasal layers of non-keratinized stratified squamous epithelium (like the oral mucosa). The mutation leads to a defect in the normal keratinization process, resulting in thick, bilateral, white, "spongy" plaques on the buccal mucosa. Histologically, it is characterized by significant **parakeratosis and intracellular edema** (clear cell change) of the spinous layer. **Analysis of Incorrect Options:** * **Erythema Multiforme:** This is an acute, self-limiting **Type IV hypersensitivity reaction** (often triggered by HSV or drugs). It involves subepithelial or intraepithelial vesiculation and "target lesions," not a primary keratinization defect. * **Incontinentia Pigmenti:** This is an X-linked dominant disorder affecting the skin, teeth, and CNS. It is characterized by a defect in the **IKBKG gene**, leading to melanin incontinence (pigment falling into the dermis), not a primary oral keratinization defect. * **Systemic Sclerosis:** This is an autoimmune connective tissue disorder characterized by **excessive collagen deposition** and fibrosis of the skin and internal organs. Oral manifestations include microstomia and widening of the PDL space, but the underlying pathology is fibrotic, not a keratin defect. **High-Yield Clinical Pearls for NEET-PG:** * **Gene Mutation:** KRT4 and KRT13 (highly specific for WSN). * **Clinical Presentation:** Asymptomatic, white, folded/velvety patches that appear in early childhood and do not disappear when stretched (unlike Leukoedema). * **Differential Diagnosis:** Must be distinguished from **Leukoplakia** (premalignant) and **Candidiasis** (scrapable). WSN is entirely benign and requires no treatment.

Question 1

What is the most common fixative used in pathology?

Accepted Answer

Formaldehyde

Answer

Gluteraldehyde

Answer

Alcohol

Answer

Picric acid

Question 2

Which of the following cytoplasmic structures contains fragmented mitochondria?

Accepted Answer

Autophagosomes

Answer

Pinocytotic vacuoles

Answer

Primary lysosomes

Answer

Heterophagosomes

Question 3

Alpha fetoprotein is genetically and structurally related to which of the following proteins?

Accepted Answer

Albumin

Answer

Transferrin

Answer

Fibrinogen

Answer

Growth hormone

Question 4

Chronic urethral obstruction due to benign prostatic hyperplasia can lead to which of the following changes in the kidney parenchyma?

Accepted Answer

Atrophy

Answer

Hyperplasia

Answer

Hypertrophy

Answer

Dysplasia

Question 5

Which of the following conditions is due to a defect in the normal keratinization of the oral mucosa?

Accepted Answer

White sponge nevus

Answer

Erythema multiforme

Answer

Incontinentia pigmenti

Answer

Systemic sclerosis

Question 6

Which of the following is NOT a chemokine?

Accepted Answer

Histamine

Answer

IL-8

Answer

IL-1

Answer

Eotaxin

Question 7

Chromosomal studies are best done during which stage of the cell cycle?

Accepted Answer

Metaphase

Answer

Prophase

Answer

Telophase

Answer

Anaphase

Question 8

Platelet dense granules contain all except?

Accepted Answer

vWF

Answer

ADP

Answer

5-HT

Answer

Calcium

Question 9

What is the characteristic appearance of a 'lardaceous spleen'?

Accepted Answer

Amyloidosis

Answer

Chronic Myeloid Leukemia (CML)

Answer

Hodgkin's lymphoma

Answer

Malaria

Question 10

In comparison to hyperplasia, hypertrophy is defined as?

Accepted Answer

Increase in cell size without an increase in number

Answer

Increase in cell size and number

Answer

Increase in cell number without an increase in size

Answer

Increase in cell size and decrease in number

General Pathology — MCQs

General Pathology — MCQs

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