General Pathology Practice Questions

Q: Which stain is used for glycogen?

PAS (Periodic Acid-Schiff). **Explanation:** **PAS (Periodic Acid-Schiff)** is the correct answer because it is the gold-standard histochemical stain for detecting carbohydrates, specifically **glycogen**, glycoproteins, and mucins. The mechanism involves periodic acid oxidizing the carbon-carbon bonds in glucose residues to form aldehydes, which then react with the Schiff reagent to produce a characteristic **magenta/deep pink** color. **Analysis of Incorrect Options:** * **Congo Red:** This is the specific stain for **Amyloid**. Under polarized microscopy, amyloid stained with Congo red exhibits a pathognomonic "apple-green birefringence." * **Prussian Blue (Perl’s Stain):** This is used to detect **Ferric iron ($Fe^{3+}$)**. It is clinically significant in diagnosing conditions like hemochromatosis or identifying sideroblasts and hemosiderin-laden macrophages ("heart failure cells"). * **Alcian Blue:** This stain is used for **acidic mucopolysaccharides** (glycosaminoglycans). It is frequently used to identify intestinal metaplasia (Barrett’s esophagus) where it stains goblet cells blue. **Clinical Pearls for NEET-PG:** * **Diastase Sensitivity:** To confirm that PAS-positive staining is specifically due to glycogen (and not other carbohydrates), a **Diastase** test is performed. Diastase digests glycogen; if the staining disappears after treatment, it confirms the presence of glycogen. * **PAS-Positive Structures:** Basement membranes, fungal hyphae (e.g., Candida, Histoplasma), and the thick secretions in Whipple’s disease (Tropheryma whipplei) are all PAS-positive. * **Best’s Carmine:** An older, highly specific stain for glycogen, though less commonly used today than PAS.

Q: What is considered the most severe form of Ehlers-Danlos syndrome?

Type 4. **Explanation:** **Ehlers-Danlos Syndrome (EDS)** is a heterogeneous group of inherited connective tissue disorders characterized by defects in collagen synthesis [1]. **Why Type 4 is Correct:** **Type 4 (Vascular Type)** is considered the most severe and life-threatening form of EDS. It results from a mutation in the **COL3A1 gene**, leading to deficient synthesis of **Type III collagen**. Since Type III collagen is a major structural component of blood vessels and hollow organs, patients are predisposed to spontaneous **rupture of large arteries** (e.g., aorta), **bowel perforation**, and **uterine rupture** during pregnancy [1]. These catastrophic events often lead to sudden death at a young age. **Analysis of Incorrect Options:** * **Type 1 & 2 (Classical Type):** These are caused by mutations in **Type V collagen** (COL5A1, COL5A2). While they present with significant skin hyperextensibility, "cigarette paper" scarring, and joint hypermobility, they are generally not life-threatening [1]. * **Type 8 (Periodontal Type):** This is a rare variant characterized primarily by severe early-onset periodontitis leading to premature loss of teeth and skin fragility, but it lacks the fatal systemic complications of the vascular type. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Most EDS types are Autosomal Dominant (including Types 1, 2, and 4). * **Kyphoscoliotic Type (Type 6):** Notable for lysyl hydroxylase deficiency; presents with ocular fragility (corneal rupture) [1]. * **Key Clinical Triad:** Hyperextensible skin, hypermobile joints, and fragile tissues (poor wound healing) [1]. * **Vascular EDS Sign:** Translucent skin with visible underlying veins and characteristic "aged" facial features (acrogeria). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 154-156.

Q: Which of the following is characteristic of a dental cyst?

Has a cystic lining of stratified squamous epithelium. **Explanation:** A **Dental Cyst** (also known as a **Radicular Cyst** or Periapical Cyst) is the most common inflammatory odontogenic cyst. It typically forms at the apex of a non-vital (necrotic) tooth due to inflammation following dental caries or pulpitis [1]. **1. Why Option D is correct:** The hallmark histological feature of a dental cyst is a lumen lined by **non-keratinized stratified squamous epithelium**. This lining is derived from the **Rest Cells of Malassez** (remnants of Hertwig’s epithelial root sheath) found in the periodontal ligament, which proliferate in response to inflammatory cytokines. **2. Why other options are incorrect:** * **Option A:** This describes a **Dentigerous Cyst** (Follicular Cyst). Dentigerous cysts originate from the reduced enamel epithelium and surround the crown of an unerupted tooth. * **Option B:** This describes an **Odontogenic Keratocyst (OKC)** or a Primordial Cyst. A dental cyst is attached to the root of an existing tooth rather than replacing it. * **Option C:** A "missing tooth" on an X-ray associated with a radiolucency is characteristic of a **Dentigerous Cyst** (where the tooth is impacted/unerupted). In a dental cyst, the involved tooth is present in the oral cavity but is non-vital. **NEET-PG High-Yield Pearls:** * **Rushton Bodies:** Eosinophilic, linear, or arch-shaped calcifications often found within the epithelial lining of radicular cysts. * **Radiology:** Appears as a well-defined unilocular radiolucency at the periapical region. * **Cholesterol Clefts:** Frequently seen in the cyst wall with associated multinucleated giant cells. * **Key Distinction:** Radicular cyst = Non-vital tooth; Dentigerous cyst = Unerupted tooth. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Head and Neck, pp. 741-742.

Q: Which cells are most susceptible to hypoxia?

Neuron. **Explanation:** The correct answer is **A. Neuron**. **Why Neurons are Most Susceptible:** Neurons have the highest metabolic rate of any cell in the body and possess virtually no capacity for anaerobic metabolism. They rely almost exclusively on a continuous supply of oxygen and glucose to maintain the ATP-dependent sodium-potassium pumps ($Na^+/K^+$ ATPase). When hypoxia occurs, ATP levels plummet rapidly, leading to pump failure, cellular swelling (cytotoxic edema), and irreversible damage. Irreversible brain damage typically begins after only **3–5 minutes** of total anoxia. Within the brain, the most sensitive areas are the **Pyramidal cells of the Hippocampus (CA1)** and the **Purkinje cells of the Cerebellum**. **Why Other Options are Incorrect:** * **B. Myocytes:** While cardiac muscle is sensitive to hypoxia, it can survive for approximately 20–30 minutes before irreversible necrosis occurs. Skeletal muscle is even more resistant, capable of surviving several hours of ischemia. * **C. Hepatocytes:** The liver has a dual blood supply (portal vein and hepatic artery) and cells contain significant glycogen stores, making them more resilient to hypoxic insult than neurons. * **D. Epithelium:** Epithelial cells (like those in the skin or GI tract) have lower metabolic demands and can tolerate hypoxia for significantly longer periods compared to neural tissue. **NEET-PG High-Yield Pearls:** * **Order of Susceptibility:** Neurons > Cardiac Myocytes > Hepatocytes > Skeletal Muscle > Connective Tissue. * **Vulnerable Brain Regions:** Hippocampus (Sommer’s sector) > Purkinje cells > Neocortex (Layers III, V, VI) > Striatum. * **Haldane Effect vs. Bohr Effect:** Often tested alongside neuro-respiratory physiology; remember that the Bohr effect describes how $CO_2/H^+$ affects $O_2$ affinity, whereas the Haldane effect describes how $O_2$ affects $CO_2$ affinity.

Question 1

Metastatic calcification is seen in:

Accepted Answer

Normal tissues

Answer

Cysts

Answer

Atheroma

Answer

Infarcts

Question 2

Which stain is used for glycogen?

Accepted Answer

PAS (Periodic Acid-Schiff)

Answer

Congo red

Answer

Prussian blue

Answer

Alcian blue

Question 3

Which of the following does not occur in lysosomal storage disorders?

Accepted Answer

No neurological deficit

Answer

Increased number and size of lysosomes

Answer

Accumulation of polyubiquinated proteins

Answer

Apoptosis defects

Question 4

Which of the following structures is seen in all except?

Accepted Answer

Follicular carcinoma of thyroid

Answer

Papillary carcinoma of thyroid

Answer

Serous cystadenoma of ovary

Answer

Meningioma

Question 5

What is considered the most severe form of Ehlers-Danlos syndrome?

Accepted Answer

Type 4

Answer

Type 1

Answer

Type 2

Answer

Type 8

Question 6

Which of the following is characteristic of a dental cyst?

Accepted Answer

Has a cystic lining of stratified squamous epithelium

Answer

Occurs from the reduced enamel epithelium

Answer

Replaces the tooth to which it is attached

Answer

Is frequently seen with a missing tooth on the X-ray

Question 7

BRAF gene mutation is seen in which of the following conditions?

Accepted Answer

Melanoma

Answer

Breast carcinoma

Answer

Osteosarcoma

Answer

Prostate carcinoma

Question 8

Which cells are most susceptible to hypoxia?

Accepted Answer

Neuron

Answer

Myocytes

Answer

Hepatocytes

Answer

Epithelium

Question 9

What is the most reliable investigation for amyloidosis?

Accepted Answer

Kidney biopsy

Answer

Abdominal fat pad aspirate

Answer

Ultrasound (USG)

Answer

Urine examination

Question 10

Which of the following is NOT a pathologic effect of free radicals?

Accepted Answer

Synthesis of new proteins.

Answer

Lipid peroxidation in membranes.

Answer

Oxidative modification of proteins.

Answer

Single- and double-strand breaks in DNA.

General Pathology — MCQs

General Pathology — MCQs

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