General Pathology Practice Questions

Q: Which cells are typically positive for CD16 and CD56 markers?

NK cells. **Explanation:** **NK (Natural Killer) cells** are large granular lymphocytes that form a critical part of the innate immune system [1]. They are characterized by the expression of two primary surface markers: 1. **CD16:** Also known as Fc̹RIII, it acts as a low-affinity receptor for the Fc portion of IgG, mediating **Antibody-Dependent Cellular Cytotoxicity (ADCC)**. 2. **CD56:** Also known as Neural Cell Adhesion Molecule (NCAM), it is the definitive marker used to identify NK cells in clinical pathology. **Analysis of Incorrect Options:** * **B Lymphocytes:** Characterized by markers **CD19, CD20, and CD21**. They also express MHC Class II and surface Immunoglobulins (sIg) [1]. * **Helper T Lymphocytes (Th):** These are defined by the presence of **CD3** (pan-T cell marker) and **CD4** [1]. * **Cytotoxic T Lymphocytes (Tc):** These are defined by **CD3** and **CD8** [1]. While some activated CD8+ T cells may occasionally express CD16, the combination of CD16 and CD56 is the classic signature for NK cells. **High-Yield Clinical Pearls for NEET-PG:** * **NK Cell Function:** They do not require prior sensitization and kill cells that show "missing self" (downregulation of MHC-I), a common tactic used by viruses and tumor cells [1]. * **CD56 Bright vs. Dim:** CD56^bright cells are primarily cytokine producers (IFN-̳), while CD56^dim cells (which are CD16+) are more potently cytotoxic. * **Chediak-Higashi Syndrome:** A high-yield association where NK cell function is impaired due to defective vesicle trafficking. * **Marker Tip:** If a question mentions **CD16, CD56, and CD3 negative**, it is definitively an NK cell. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 200-201.

Q: What is the hairpin-shaped eosinophilic structure present in a radicular cyst?

Rushton bodies. **Explanation:** **Rushton bodies** (Option A) are the correct answer. These are unique, eosinophilic, calcified microscopic structures found within the epithelial lining of odontogenic cysts, most commonly the **Radicular cyst** [1]. They are characterized by their distinct morphology, often described as **hairpin-shaped**, linear, straight, or polycyclic. While their exact origin is debated, they are generally considered to be a secretory product of the odontogenic epithelium [1]. **Why other options are incorrect:** * **Russell bodies (Option B):** These are eosinophilic, large, homogeneous immunoglobulin-containing inclusions found in the cytoplasm of **plasma cells** undergoing excessive synthesis of antibodies. They are associated with chronic inflammation (e.g., Rhinoscleroma) but do not have a "hairpin" shape and are not specific to odontogenic cyst epithelium. * **Option C and D:** These are incorrect as Rushton bodies and Russell bodies are distinct entities with different origins and morphologies. **High-Yield Clinical Pearls for NEET-PG:** * **Radicular Cyst:** The most common inflammatory odontogenic cyst, typically found at the apex of a non-vital tooth [1]. * **Histology of Radicular Cyst:** Look for stratified squamous epithelial lining, **Rushton bodies**, and "Cholesterol clefts" with associated giant cells in the fibrous capsule [1]. * **Differentiating "Bodies":** * **Rushton:** Odontogenic cysts (Hairpin/Linear). * **Russell:** Plasma cells (Immunoglobulins). * **Negri:** Rabies (Intracytoplasmic in neurons). * **Psammoma:** Papillary thyroid CA, Meningioma, Mesothelioma, Serous cystadenocarcinoma of ovary (Laminated calcifications). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Head and Neck, pp. 741-742.

Question 1

Which one of the following disorders is autosomal recessive?

Accepted Answer

Tay-Sachs disease

Answer

Adult polycystic kidney disease

Answer

Marfan syndrome

Answer

Familial hypercholesterolemia

Question 2

Oval stem cells are located in?

Accepted Answer

Canal of Herring

Answer

Canal of Schlemm

Answer

Space of Disse

Answer

Basal lamina of myotubules

Question 3

Which of the following is NOT an example of physiological apoptosis?

Accepted Answer

Graft versus host disease

Answer

Organogenesis

Answer

Hormonal dependent apoptosis

Answer

Selective death of lymphocytes

Question 4

What is the most common source of embolism?

Accepted Answer

Deep vein thrombosis (DVT)

Answer

Trauma

Answer

Infection

Answer

Surgery

Question 5

Which cells are typically positive for CD16 and CD56 markers?

Accepted Answer

NK cells

Answer

B Lymphocytes

Answer

Helper T lymphocyte

Answer

Cytotoxic T lymphocyte

Question 6

Which of the following occurs in ischemic cell injury?

Accepted Answer

Influx of Na+ and Ca++

Answer

Efflux of K+ and Na+

Answer

Influx of K+ and Ca++

Answer

Influx of K+ and H2O

Question 7

Which of the following is not an example of fibrinoid necrosis?

Accepted Answer

Pancreatitis

Answer

Polyarteritis nodosa (PAN)

Answer

Rheumatoid arthritis

Answer

Rheumatic fever

Question 8

What is the hairpin-shaped eosinophilic structure present in a radicular cyst?

Accepted Answer

Rushton bodies

Answer

Russell bodies

Answer

Both of the above

Answer

None of the above

Question 9

Amyloid is stained with:

Accepted Answer

Congo red

Answer

Lugol's iodine

Answer

Methyl violet

Answer

Sudan black

Question 10

The mucin clot test is performed to detect which of the following?

Accepted Answer

Hyaluronate in synovial fluid

Answer

Mucin in stool

Answer

Protein in cerebrospinal fluid

Answer

Protein in pleural fluid

General Pathology — MCQs

General Pathology — MCQs

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