General Pathology — MCQs

General Pathology Indian Medical PG Practice Questions and MCQs

Question 751: Non-caseating granuloma is characteristically seen in:

A. Syphilis
B. Sarcoidosis (Correct Answer)
C. Tuberculosis
D. Cat-scratch disease

Explanation: ### Explanation **Correct Answer: B. Sarcoidosis** **Mechanism:** A granuloma is a focal collection of inflammatory cells, primarily epithelioid macrophages, surrounded by a collar of lymphocytes and occasional plasma cells. In **Sarcoidosis**, the granulomas are characteristically **non-caseating** (lacking central "cheese-like" necrosis) [1], [2]. This is a Type IV hypersensitivity reaction to an unidentified antigen. Microscopically, these granulomas often contain **Schaumann bodies** (laminated calcium-protein concretions) and **Asteroid bodies** (stellate inclusions within giant cells). **Analysis of Incorrect Options:** * **A. Syphilis:** Characterized by a **Gumma**, which is a specific type of granuloma with central coagulative necrosis (rubbery consistency) and prominent endarteritis obliterans. * **C. Tuberculosis:** The hallmark of TB is **caseating granuloma**. The central area undergoes "cheesy" necrosis due to the lipid-rich cell wall of *Mycobacterium tuberculosis*. * **D. Cat-scratch disease:** Caused by *Bartonella henselae*, it typically presents with **stellate (star-shaped) necrotizing granulomas** that often contain central neutrophils (suppurative). **High-Yield Clinical Pearls for NEET-PG:** * **Sarcoidosis Diagnosis:** It is a diagnosis of exclusion. Look for bilateral hilar lymphadenopathy on CXR and elevated Serum ACE levels [2]. * **Other Non-caseating Granulomas:** Berylliosis, Crohn’s disease, Lepromatous leprosy (though often poorly formed), and Foreign body reactions [1]. * **Stains:** Always use **Ziehl-Neelsen (ZN) stain** to rule out TB before diagnosing Sarcoidosis, as both can present with similar pulmonary symptoms. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 198-200. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 700-701.

Question 752: Down's syndrome is associated with mental retardation. Which of the following chromosomal abnormalities are not typically found in Down's syndrome?

A. Deletion of chromosome 21 (Correct Answer)
B. Trisomy 21
C. Translocation involving chromosome 21 (e.g., t(13,21), t(21,21))
D. Mosaicism with trisomy 21

Explanation: Down’s syndrome (Trisomy 21) is the most common chromosomal disorder and a leading cause of intellectual disability [1]. The fundamental genetic defect is an **excess of genetic material** from chromosome 21, not a deficiency. **1. Why "Deletion of chromosome 21" is the correct answer:** A deletion refers to the loss of a chromosomal segment. In Down’s syndrome, the pathology is driven by **gene overdosage** (specifically within the Down Syndrome Critical Region). A deletion of chromosome 21 would result in a different clinical syndrome (Monosomy 21), which is generally incompatible with life or presents with entirely different phenotypic features [1]. **2. Analysis of Incorrect Options:** * **Trisomy 21 (95% of cases):** The most common cause, usually due to meiotic non-disjunction (correlated with advanced maternal age) [1]. * **Translocation (4% of cases):** Occurs when the long arm of chromosome 21 attaches to another chromosome (usually 14 or 22) [1]. This is "Robertsonian translocation." Unlike non-disjunction, this can be inherited from a carrier parent. * **Mosaicism (1% of cases):** Results from mitotic non-disjunction during early fetal development [1]. These individuals have two cell lines (one normal, one trisomic) and often exhibit a milder phenotype. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause:** Meiotic non-disjunction (occurs during Meiosis I). * **Cardiac defect:** Endocardial cushion defects (ASD/VSD) are most common. * **GI associations:** Duodenal atresia ("Double bubble" sign) and Hirschsprung disease. * **Hematology:** Increased risk of **AMKL** (Acute Megakaryoblastic Leukemia) before age 5 and **ALL** after age 5. * **Neurology:** Early-onset Alzheimer’s disease due to APP gene overdosage on chromosome 21 [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 168-172. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 720-721.

Question 753: Bone marrow in Amyloid Lightchain Amyloidosis shows which of the following features?

A. Bone marrow plasmacytosis (Correct Answer)
B. Granulomatous reaction
C. Fibrosis
D. Giant cell formation

Explanation: ### Explanation **Correct Option: A. Bone marrow plasmacytosis** **Reasoning:** Amyloid Light-chain (AL) Amyloidosis is a plasma cell dyscrasia. It is caused by a clonal population of plasma cells in the bone marrow that produce excessive amounts of **monoclonal immunoglobulin light chains** (typically Lambda > Kappa) [1]. these light chains undergo partial proteolysis to form amyloid fibrils that deposit in tissues. In the bone marrow of patients with AL amyloidosis, the most characteristic finding is **plasmacytosis** (an increased number of plasma cells) [1]. While these cells are often fewer than the 10% threshold required for a diagnosis of Multiple Myeloma, they are clonal and responsible for the disease pathology. **Why other options are incorrect:** * **B. Granulomatous reaction:** This is a feature of chronic granulomatous diseases (like Tuberculosis or Sarcoidosis). Amyloid is an extracellular protein deposit and does not typically incite a granulomatous response. * **C. Fibrosis:** While chronic marrow infiltration can lead to secondary fibrosis, it is not a diagnostic or characteristic feature of AL amyloidosis. * **D. Giant cell formation:** Giant cells are seen in foreign body reactions or granulomatous inflammation. Amyloid deposits are "inert" and do not typically trigger giant cell formation in the marrow. --- ### NEET-PG High-Yield Pearls: * **Staining:** Amyloid shows **Apple-green birefringence** under polarized light when stained with **Congo Red**. * **Most Common Type:** AL amyloidosis is the most common form of systemic amyloidosis [1]. * **Organ Involvement:** The kidney is the most frequently involved organ in AL amyloidosis (presenting as nephrotic syndrome), followed by the heart (restrictive cardiomyopathy). * **Diagnosis:** The gold standard for diagnosis is a tissue biopsy (fat pad aspiration or rectal biopsy are common screening sites). * **Precursor Protein:** In AL amyloidosis, the precursor is the **L**ight chain; in AA (Reactive) amyloidosis, it is the **S**erum **A**myloid **A**ssociated (SAA) protein. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 266-267.

Question 754: Which of the following is an example of a direct acting toxin?

A. Acetaminophen
B. Mercuric chloride (Correct Answer)
C. Carbon tetrachloride
D. Bromobenzene

Explanation: Chemical injury to cells occurs via two major mechanisms: **Direct toxicity** (where the chemical acts directly by binding to critical molecular components) and **Indirect toxicity** (where the chemical must be converted into reactive toxic metabolites, usually by cytochrome P-450) [3]. **Why Mercuric Chloride is correct:** Mercuric chloride is a classic example of a **direct-acting toxin**. It binds directly to the sulfhydryl groups of various cell membrane proteins and enzymes. This leads to increased membrane permeability and inhibition of ATPase-dependent transport, causing rapid cell death [4]. It primarily affects the cells that use, absorb, or excrete it, such as the gastrointestinal tract and the kidneys (causing acute tubular necrosis). **Analysis of Incorrect Options:** * **Acetaminophen (Option A):** It is an indirect toxin. While the drug itself is non-toxic, it is converted by P-450 in the liver into a highly reactive toxic metabolite called **NAPQI**, which causes lipid peroxidation and liver necrosis [3, 4]. * **Carbon tetrachloride (Option C):** This is the prototype of indirect toxicity. It is converted by P-450 into the **trichloromethyl free radical (·CCl3)**, which causes membrane damage and fatty change in the liver. * **Bromobenzene (Option D):** Similar to acetaminophen, it is metabolized by the liver's microsomal enzyme system into toxic epoxides, making it an indirect toxin. **High-Yield NEET-PG Pearls:** * **Direct Toxins:** Mercuric chloride, Cyanide (inhibits cytochrome oxidase), and Antineoplastic/Chemotherapeutic agents [1]. * **Indirect Toxins:** CCl4, Acetaminophen, Bromobenzene, and Cyclophosphamide. * **Target Organ:** The kidney is the main target for Mercuric chloride (Direct), while the liver is the primary site for CCl4 and Acetaminophen (Indirect) due to high P-450 activity. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 330-331. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 99-100. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Liver and Gallbladder, pp. 847-848. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, p. 933.

Question 755: Arbiskov cells are seen in which of the following conditions?

A. Myeloblastoma (Correct Answer)
B. Neuroblastoma
C. Leiomyosarcoma
D. Retinoblastoma

Explanation: **Explanation:** **Arbiskov cells** (also known as Abrikossoff cells) are the characteristic histological feature of **Granular Cell Tumors**, historically referred to as **Myeloblastoma** (specifically, Granular Cell Myeloblastoma). 1. **Why Myeloblastoma is correct:** Granular cell tumors are benign neoplasms, likely of Schwann cell origin. Under the microscope, they consist of large, polygonal cells with abundant, eosinophilic, and coarsely granular cytoplasm—these are the **Arbiskov cells**. The granules represent an accumulation of lysosomes (PAS-positive and diastase-resistant). While the term "Myeloblastoma" is an older nomenclature, it remains a high-yield synonym in competitive exams like NEET-PG. 2. **Why the other options are incorrect:** * **Neuroblastoma:** Characterized by small round blue cells and **Homer-Wright rosettes** [1]. * **Leiomyosarcoma:** A malignant tumor of smooth muscle characterized by spindle cells with "cigar-shaped" nuclei and a fascicular growth pattern. * **Retinoblastoma:** Characterized by **Flexner-Wintersteiner rosettes** (pathognomonic) and Homer-Wright rosettes. **Clinical Pearls for NEET-PG:** * **Most common site:** The **tongue** is the most frequent location for Granular Cell Tumors. * **Pseudoepitheliomatous Hyperplasia (PEH):** The overlying epithelium in these tumors often shows marked hyperplasia, which can be mistaken for Squamous Cell Carcinoma (a common diagnostic pitfall). * **Immunohistochemistry (IHC):** These cells are strongly positive for **S-100**, confirming their neural (Schwann cell) origin. * **Staining:** The granules are **PAS-positive** and diastase-resistant. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 419-420.

Question 756: What is the term for localized Langerhans cell histiocytosis affecting the head and neck?

A. Letterer-Siwe disease
B. Pulmonary Langerhans cell histiocytosis
C. Eosinophilic granuloma (Correct Answer)
D. None of the above

Explanation: **Explanation:** **Langerhans Cell Histiocytosis (LCH)** is a spectrum of disorders characterized by the clonal proliferation of Langerhans cells (expressing CD1a, S100, and CD207/Langerin) [1]. The clinical presentation depends on the extent of involvement. **Why Eosinophilic Granuloma is correct:** **Eosinophilic Granuloma** is the most benign and localized form of LCH. It typically presents as a **solitary, osteolytic lesion** in the bones, most commonly affecting the skull (head), mandible (neck), ribs, or femur. It is usually seen in older children or young adults and carries an excellent prognosis. **Analysis of Incorrect Options:** * **A. Letterer-Siwe disease:** This is the **acute disseminated** (multisystem) form of LCH, typically occurring in infants under age 2. It involves multiple organs (skin, liver, spleen, bone marrow) and has a poor prognosis. * **B. Pulmonary LCH:** This is a localized form specifically affecting the lungs, almost exclusively seen in **adult smokers**. While localized, it is not the classic term for head and neck bone involvement. * **Hand-Schüller-Christian disease (Note):** Though not an option, this is the chronic disseminated form characterized by the classic triad of calvarial bone defects, diabetes insipidus, and exophthalmos. **NEET-PG High-Yield Pearls:** 1. **Birbeck Granules:** Pathognomonic electron microscopy finding; described as **"tennis-racket"** shaped pentalaminar structures [1]. 2. **Immunohistochemistry (IHC):** Positive for **CD1a, S100, and Langerin (CD207)** [1]. 3. **BRAF V600E Mutation:** Present in approximately 50% of LCH cases [1]. 4. **Radiology:** "Punched-out" radiolucent lesions without a sclerotic rim are characteristic in the skull. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 629-630.

Question 757: Birbeck granules are characteristically present in which of the following cells?

A. Merkel cell
B. Melanocyte
C. Langerhans cell (Correct Answer)
D. Keratinocyte

Explanation: **Explanation:** **Langerhans cells** are specialized dendritic cells (antigen-presenting cells) primarily located in the stratum spinosum of the epidermis. The pathognomonic ultrastructural feature of these cells is the **Birbeck granule** [1]. Under electron microscopy, these are rod-shaped, pentalaminar cytoplasmic organelles with a central striated line and a bulbous end, giving them a characteristic **"tennis racket" appearance** [1]. They contain the protein **Langerin (CD207)**, which is involved in the endocytosis and degradation of viruses [1]. **Analysis of Options:** * **Merkel cells (Option A):** These are neuroendocrine cells involved in light touch sensation. They contain membrane-bound dense-core neurosecretory granules, not Birbeck granules. * **Melanocytes (Option B):** These cells are derived from the neural crest and produce pigment. Their characteristic organelles are **melanosomes**, which contain melanin. * **Keratinocytes (Option D):** The predominant cells of the epidermis. They are characterized by intermediate filaments (keratins) and **Odland bodies** (lamellar bodies) in the upper layers, but lack Birbeck granules. **High-Yield Clinical Pearls for NEET-PG:** * **Langerhans Cell Histiocytosis (LCH):** A neoplastic proliferation of Langerhans cells [1]. Diagnosis is confirmed by the presence of Birbeck granules on EM or immunohistochemistry markers: **CD1a, S100, and Langerin (CD207)** [1]. * **Origin:** Unlike other skin cells, Langerhans cells originate from the **bone marrow** (monocyte-macrophage lineage). * **Function:** They capture antigens and migrate to local lymph nodes to present them to T-lymphocytes. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 629-630.

Question 758: What is the most common extragonadal site for germ cell tumors?

A. Retroperitoneum
B. Sacrococcygeal region
C. Pineal gland
D. Mediastinum (Correct Answer)

Explanation: **Explanation:** Germ cell tumors (GCTs) typically arise in the gonads (testes and ovaries). However, during embryogenesis, primordial germ cells migrate from the yolk sac endoderm to the gonadal ridges. If these cells fail to reach the gonads or stray from the migratory path, they can give rise to **Extragonadal Germ Cell Tumors (EGGCTs)**, which always occur in midline structures. **Why Mediastinum is correct:** In the **adult population**, the **mediastinum** (specifically the anterior mediastinum) is the most common site for extragonadal germ cell tumors. They represent about 50-70% of all adult EGGCTs. **Analysis of Incorrect Options:** * **Sacrococcygeal region:** This is the most common site for extragonadal GCTs (specifically Teratomas) in **infants and children**, but it is less common than the mediastinum when considering the overall population or adult-specific data often tested in PG exams. * **Retroperitoneum:** This is the second most common site in adults. However, a primary retroperitoneal GCT must be distinguished from a metastatic deposit from an occult testicular primary (Burned-out tumor). * **Pineal gland:** This is a common site for intracranial GCTs (Germinomas) [1], but it is less frequent overall compared to the mediastinum. **High-Yield Clinical Pearls for NEET-PG:** 1. **Most common mediastinal GCT:** Teratoma (usually benign in females, potentially malignant in males). 2. **Klinefelter Syndrome (47, XXY):** Strongly associated with the development of mediastinal germ cell tumors. 3. **Tumor Markers:** Always check AFP (Yolk sac component) and ̢-hCG (Choriocarcinoma component) for diagnosis and monitoring. 4. **Rule of Thumb:** Any midline mass in a young adult should raise suspicion for a Germ Cell Tumor. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1140-1141.

Question 759: Which of the following is associated with C-ANCA?

A. Proteinase 3 (Correct Answer)
B. Myeloperoxidase
C. Alkaline phosphatase
D. Lactate dehydrogenase

Explanation: **Explanation:** **C-ANCA (Cytoplasmic Antineutrophil Cytoplasmic Antibody)** is a specific pattern seen on immunofluorescence where the staining is distributed throughout the cytoplasm of neutrophils. 1. **Why Proteinase 3 is correct:** The primary target antigen for C-ANCA is **Proteinase 3 (PR3)**, a serine protease found in the azurophilic granules of neutrophils [2]. This association is highly specific (approx. 90%) for **Granulomatosis with Polyangiitis (GPA)**, formerly known as Wegener’s Granulomatosis [1]. 2. **Why other options are incorrect:** * **Myeloperoxidase (MPO):** This is the target antigen for **P-ANCA** (Perinuclear pattern). P-ANCA is typically associated with Microscopic Polyangiitis (MPA), Churg-Strauss Syndrome (EGPA), and Primary Sclerosing Cholangitis. * **Alkaline phosphatase & Lactate dehydrogenase:** These are general serum enzymes used as markers for hepatobiliary disease/bone turnover and tissue damage/hemolysis, respectively. They have no association with ANCA patterns or systemic vasculitis. **High-Yield Clinical Pearls for NEET-PG:** * **C-ANCA / PR3-ANCA:** Marker for **Granulomatosis with Polyangiitis**. Classic triad: Upper respiratory tract (sinusitis), Lower respiratory tract (hemoptysis/cavitation), and Renal involvement (crescentic GN) [2]. * **P-ANCA / MPO-ANCA:** Marker for **Microscopic Polyangiitis** and **Churg-Strauss Syndrome** (look for asthma and eosinophilia). * **Monitoring:** ANCA titers often correlate with disease activity; a rise in titers may predict a relapse in patients with GPA [2]. * **Staining Pattern:** C-ANCA shows diffuse cytoplasmic staining, while P-ANCA shows staining around the nucleus (perinuclear) due to an artifact during ethanol fixation. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 917-918. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 519-520.

Question 760: Dissolution of nuclear chromatin and fading of chromatin is known as:

A. Pyknosis
B. Karyolysis (Correct Answer)
C. Karyorrhexis
D. Emiocytosis

Explanation: **Explanation:** The question describes the characteristic nuclear changes seen during irreversible cell injury and necrosis. **1. Why Karyolysis is correct:** **Karyolysis** refers to the dissolution of the nucleus [1]. It is characterized by the **fading of chromatin basophilia** (basolysis), reflecting the loss of DNA due to enzymatic degradation by endonucleases and DNases. On light microscopy, the nucleus appears pale and eventually disappears completely [1]. **2. Analysis of Incorrect Options:** * **Pyknosis:** This is the initial stage of nuclear shrinkage [1]. It is characterized by **nuclear condensation** and increased basophilia (the nucleus appears as a small, shrunken, dark-blue mass) [1]. * **Karyorrhexis:** This follows pyknosis [1]. The pyknotic nucleus undergoes **fragmentation**, breaking apart into multiple small, dense "nuclear dust" particles [1]. * **Emiocytosis:** Also known as exocytosis, this is a physiological process where cell contents (like hormones or neurotransmitters) are released via vesicles. It is unrelated to cell death or nuclear degradation. **3. NEET-PG High-Yield Pearls:** * **Sequence of Nuclear Changes:** Pyknosis (Shrinkage) → Karyorrhexis (Fragmentation) → Karyolysis (Dissolution) [1]. * **Biochemical Basis:** These changes are driven by the activation of lysosomal enzymes in a low pH environment. * **Morphology of Necrosis:** Beyond nuclear changes, the cytoplasm becomes more **eosinophilic** (pinker) due to the loss of cytoplasmic RNA and the binding of eosin to denatured proteins [1]. * **Apoptosis vs. Necrosis:** While karyorrhexis can occur in both, **karyolysis is specific to necrosis.** In apoptosis, the nucleus fragments into membrane-bound apoptotic bodies without complete enzymatic dissolution. **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.

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Hemodynamic Disorders

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Genetic Disorders

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Environmental Pathology

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Molecular Basis of Disease

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