General Pathology — MCQs

A 28-year-old woman is pinned by falling debris during a hurricane. An X-ray film of the leg reveals a compound fracture of the right tibia. The leg is immobilized in a cast for 6 weeks. When the cast is removed, the patient notices that her right leg is weak and visibly smaller in circumference than the left leg. Which of the following terms best describes this change in the patient's leg muscle?

Q1366

In a patient with gouty arthritis, synovial fluid aspiration will show:

Q1367

Radiation mediates its effect by

Q1368

Which of the following is most sensitive to radiation

Q1369

Who is the founder of the electron microscope?

Q1370

Which type of necrosis is characterized by deposition of immune complexes and fibrin in the walls of blood vessels?

General Pathology Indian Medical PG Practice Questions and MCQs

Question 1361: Stain used in electron microscopy

A. Phosphotungstic acid (Correct Answer)
B. Coomassie blue
C. 2.5% FAM
D. Saffranin

Explanation: ***Phosphotungstic acid*** - **Phosphotungstic acid (PTA)** is a heavy metal stain used in **electron microscopy** [2] to study the **ultrastructure** of biological specimens - It acts as a **negative stain** that increases **contrast** by scattering electrons, making cellular structures and organelles more visible [2] - Commonly used for visualizing **collagen fibers**, **fibrin**, and various **subcellular structures** [2] *Coomassie blue* - **Coomassie blue** is a dye used for detecting **proteins** in **gel electrophoresis** (such as SDS-PAGE and Bradford assay) - It is a **light microscopy stain**, not suitable for electron microscopy as it does not provide electron density contrast *2.5% FAM* - **FAM (Fluorescein Amidite)** is a **fluorescent dye** used for labeling **nucleic acids** (DNA, RNA) or **proteins** in molecular biology techniques - Commonly used in **qPCR**, **DNA sequencing**, and **FISH** (fluorescence in situ hybridization) - Not used in electron microscopy as it is designed for fluorescence detection, not electron beam visualization *Saffranin* - **Saffranin** is a **basic dye** used in **light microscopy** for staining **nuclei** in plant and animal tissues - Also used as a **counterstain** in **Gram staining** to identify **Gram-negative bacteria** (appears pink/red) - Not suitable for electron microscopy as it lacks the electron density required for contrast with electron beams [1] **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. 25-26. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 162-163.

Question 1362: Which type of radiation effect results in radiation induced thyroid cancer?

A. Teratogenic
B. Genetic
C. Somatic (Correct Answer)
D. Deterministic

Explanation: ***Somatic*** - **Somatic effects** are those that affect the irradiated individual directly, such as **cancer** [2] or cataracts, but are not passed on to offspring. - **Radiation-induced thyroid cancer** is a classic example of a **somatic effect** because the cancer develops in the exposed individual [1], [4]. - Somatic effects are typically **stochastic** (probability-based, no threshold dose) [2], [3]. *Teratogenic* - **Teratogenic effects** refer to developmental abnormalities induced during **fetal development** leading to birth defects. - While radiation can cause teratogenic effects, these manifest as birth defects in the offspring rather than cancer in the exposed individual. *Genetic* - **Genetic effects** (also known as hereditary effects) result from damage to **germ cells** (sperm or ova) and are inheritable by future generations. - Thyroid cancer affecting the exposed individual is not a genetic effect as it is not passed down to their progeny. *Deterministic* - **Deterministic effects** (also called non-stochastic effects) are radiation effects that have a **threshold dose** and whose severity increases with dose (e.g., skin burns, acute radiation syndrome) [2]. - While thyroid cancer can result from radiation, it is classified as a **stochastic somatic effect** [2] rather than a deterministic effect because it occurs randomly without a clear threshold dose [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1098-1099. [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. 112-113. [3] 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. 114-115. [4] 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. 216-217.

Question 1363: Asteroid bodies in non-caseating granulomas are characteristically seen in:

A. Sporotrichosis
B. Sarcoidosis (Correct Answer)
C. Chromoblastomycosis
D. Syphilis

Explanation: ***Sarcoidosis*** - **Asteroid bodies** are star-shaped eosinophilic cytoplasmic inclusions within **multinucleated giant cells** in **non-caseating granulomas**. - While **not pathognomonic**, they are **most classically associated with sarcoidoidosis** in medical literature and examination contexts [1]. - Sarcoidosis characteristically shows **non-caseating epithelioid granulomas** with multinucleated giant cells that may contain asteroid bodies, Schaumann bodies, or calcium oxalate crystals [1], [2]. - For examination purposes, **sarcoidosis is the standard answer** when asteroid bodies in non-caseating granulomas are mentioned. *Sporotrichosis* - Asteroid bodies **can occasionally be seen** in sporotrichosis, but they are **not a consistent or defining feature**. - Sporotrichosis is more characteristically identified by **cigar-shaped yeast forms** in tissue and the **Splendore-Hoeppli phenomenon** (eosinophilic material surrounding fungal elements). - The granulomas in sporotrichosis are typically **suppurative granulomas**, not the classic non-caseating type. *Chromoblastomycosis* - This fungal infection is characterized by **sclerotic bodies** (Medlar bodies or muriform bodies), which are thick-walled, septated, copper-colored cells. - **Asteroid bodies are not a feature** of chromoblastomycosis; the diagnostic hallmark is the presence of sclerotic bodies. *Syphilis* - Tertiary syphilis may show granulomas (gummas), but these are characterized by **central necrosis** and **perivascular plasma cell infiltrates**. - **Asteroid bodies are not associated** with syphilitic lesions; the histologic hallmark is the dense **plasma cell infiltrate**. **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 1364: Microscopically, epimyoepithelial islands are typically seen in:

A. Epithelial-myoepithelial carcinoma
B. Myoepithelioma
C. Mucoepidermoid carcinoma
D. Sjögren's syndrome (Correct Answer)

Explanation: ***Sjögren's syndrome*** - **Epimyoepithelial islands** are a characteristic histopathological feature of **Sjögren's syndrome**, particularly in affected salivary glands. [1] - These islands represent **benign lymphoepithelial lesions** where ducts are surrounded by lymphocytes, eventually forming true islands. *Epithelial-myoepithelial carcinoma* - This is a **malignant salivary gland tumor** with dual differentiation, but it typically presents as distinct inner epithelial and outer myoepithelial layers around ducts or cords, not as true "islands." - While it involves both epithelial and myoepithelial cells, its arrangement and neoplastic nature differ from the benign epimyoepithelial islands of Sjögren's. *Myoepithelioma* - This is a **benign tumor composed predominantly of myoepithelial cells**, often appearing in various morphological patterns (spindle, plasmacytoid, epithelioid, clear cell). - It does not typically form the well-defined **lymphoepithelial islands** seen in Sjögren's, as its characteristic is the proliferation of myoepithelial cells in a different architectural pattern. *Mucoepidermoid carcinoma* - This is a common **malignant salivary gland tumor** characterized by a mixture of mucin-producing cells, epidermoid cells, and intermediate cells. - Its histological features are distinct and do not include the formation of **epimyoepithelial islands**, which are diagnostically specific to Sjögren's syndrome. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 235-236.

Question 1365: A 28-year-old woman is pinned by falling debris during a hurricane. An X-ray film of the leg reveals a compound fracture of the right tibia. The leg is immobilized in a cast for 6 weeks. When the cast is removed, the patient notices that her right leg is weak and visibly smaller in circumference than the left leg. Which of the following terms best describes this change in the patient's leg muscle?

A. Hyperplasia
B. Metaplasia
C. Ischemic necrosis
D. Atrophy (Correct Answer)

Explanation: ***Atrophy*** - **Atrophy** refers to a decrease in cell size or number, leading to a reduction in organ or tissue size, which perfectly describes the **visibly smaller** and **weaker leg muscle** after prolonged immobilization [1]. - In this case, the **immobilization in a cast** for 6 weeks prevented muscle use, leading to disuse atrophy of the leg muscles [1]. *Hyperplasia* - **Hyperplasia** is an increase in the number of cells in a tissue or organ, which would result in an *increase* in tissue size, the opposite of what is seen in the patient's leg. - This process is often a response to increased functional demand or hormonal stimulation. *Metaplasia* - **Metaplasia** is the *reversible change* of one differentiated cell type to another differentiated cell type. - This typically occurs in response to chronic irritation or inflammation, such as **Barrett's esophagus**, and does not involve a reduction in tissue size due to disuse. *Ischemic necrosis* - **Ischemic necrosis** refers to cell or tissue death caused by a lack of blood supply, often leading to gangrene [2]. - While immobilization can sometimes lead to localized pressure and impaired circulation, the primary cause of muscle shrinkage in this scenario is disuse, not widespread tissue death due to ischemia. **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. 90-91. [2] 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, pp. 47-49.

Question 1366: In a patient with gouty arthritis, synovial fluid aspiration will show:

A. Calcium Pyrophosphate crystals
B. Mononuclear Leucocytosis
C. Polymorphonuclear Leukocytosis
D. Monosodium Urate crystals (Correct Answer)

Explanation: ***Monosodium Urate crystals*** - The definitive diagnosis of **gouty arthritis** is made by identifying **needle-shaped, negatively birefringent monosodium urate crystals** in the synovial fluid [1]. - These crystals are formed from **elevated uric acid levels** and precipitate in joints, triggering acute inflammation [2]. *Calcium Pyrophosphate crystals* - These crystals are characteristic of **pseudogout**, or **calcium pyrophosphate deposition disease (CPPD)**, and are typically **rhomboid-shaped and positively birefringent** [3]. - While both gout and pseudogout cause acute arthritis, the **crystal morphology and birefringence** differentiate them [3]. *Mononuclear Leucocytosis* - **Mononuclear leucocytosis** in synovial fluid is more commonly seen in **chronic inflammatory conditions** or some **viral arthritides**, not typically in acute gout attacks. - Acute gout is characterized by a strong **neutrophilic inflammatory response** [1]. *Polymorphonuclear Leukocytosis* - While **polymorphonuclear leukocytosis** (predominantly neutrophils) is indeed seen in the synovial fluid of patients with acute gout due to the intense inflammatory response, it is a **non-specific finding** of inflammation [1]. - It does not definitively diagnose gout, as it can be present in other inflammatory arthritides, including **septic arthritis**, making the **crystal identification crucial**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1218-1220. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 682-683. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 683-684.

Question 1367: Radiation mediates its effect by

A. Protein coagulation
B. Osmolysis of cells
C. Ionization of the molecules (Correct Answer)
D. Denaturation of DNA

Explanation: ***Ionization of the molecules*** - Radiation, particularly **ionizing radiation**, interacts with biological molecules by ejecting electrons, leading to the formation of highly reactive **ions and free radicals** [1]. - This **ionization** process is the primary mechanism by which radiation damages cellular components, including **DNA** [2]. *Protein coagulation* - While radiation can cause protein damage, **coagulation** is not its primary or direct mechanism, especially at clinically relevant doses. - Protein coagulation is more typically associated with **heat** or certain strong chemical agents. *Osmolysis of cells* - **Osmolysis** refers to the rupture of cells due to excessive water influx, often caused by changes in osmotic pressure. - Radiation does not directly induce **osmotic imbalances** leading to cell lysis. *Denaturation of DNA* - While radiation ultimately leads to **DNA damage**, denaturation (unfolding) is a specific type of damage, often caused by heat or extreme pH. - The direct effect of radiation is **ionization**, which then indirectly causes various forms of DNA damage including breaks, cross-links, and base modifications, but not solely "denaturation" [1]. **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. 101-102. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Central Nervous System Synapse, pp. 436-437.

Question 1368: Which of the following is most sensitive to radiation

A. Stem cells
B. Skin
C. Bone
D. Lymphocyte (Correct Answer)

Explanation: ***Lymphocyte*** - **Lymphocytes** are the **most radiosensitive cells in the human body**, undergoing apoptosis at doses as low as **0.5-1 Gy**. - This extreme sensitivity is an exception to the general rule that undifferentiated cells are most radiosensitive. - **Clinical significance**: Lymphopenia is one of the earliest signs of radiation exposure, used as a biological dosimeter in radiation accidents. - The mechanism involves direct DNA damage triggering **p53-mediated apoptosis** in these immunologically active cells. *Stem cells* - **Hematopoietic stem cells** are highly radiosensitive due to their rapid proliferation and high mitotic activity [2]. - They follow the **Bergonié-Tribondeau law**: radiosensitivity increases with mitotic activity and decreases with differentiation. - However, they are slightly **less sensitive than mature lymphocytes** when comparing absolute radiosensitivity [1]. - **Bone marrow suppression** occurs at higher doses (2-4 Gy) compared to lymphocyte depletion [3]. *Skin* - **Skin** has moderate radiosensitivity due to **basal stem cells** in the epidermis [2]. - Effects include erythema (2-6 Gy), dry desquamation (8-12 Gy), and moist desquamation (>15 Gy) [3]. - Less sensitive than lymphocytes and hematopoietic cells [1]. *Bone* - **Bone tissue** (osteocytes in lacunae) is relatively **radioresistant** [1]. - The marrow within bone is radiosensitive, but this is due to **hematopoietic cells**, not the bone matrix itself. - Mature bone requires very high doses (>60 Gy) to show structural damage. **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. 111-112. [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. 104-105. [3] 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. 112-113.

Question 1369: Who is the founder of the electron microscope?

A. Ernst Ruska (Correct Answer)
B. Robert Koch
C. Antonie Philips van Leeuwenhoek
D. Louis Pasteur

Explanation: ***Ernst Ruska*** - **Ernst Ruska**, along with Max Knoll, is credited with the invention of the **electron microscope** in 1931. - His work on electron optics eventually led to the development of the **transmission electron microscope (TEM)**, which revolutionized scientific research. *Robert Koch* - **Robert Koch** was a German physician and microbiologist who is one of the founders of **modern bacteriology**. - He is famous for identifying the specific causative agents of infectious diseases such as **tuberculosis, cholera, and anthrax**, and for developing methods for culturing bacteria. *Antonie Philips van Leeuwenhoek* - **Antonie van Leeuwenhoek** is known as the **"Father of Microbiology"** due to his pioneering work in microscopy. - He was the first to observe and describe **single-celled organisms** (which he called "animalcules") and microscopic structures such as **muscle fibers, bacteria, and blood flow** in capillaries using his self-made simple microscopes. *Louis Pasteur* - **Louis Pasteur** was a French microbiologist and chemist renowned for his discoveries concerning the **principles of vaccination, microbial fermentation, and pasteurization** [1]. - He is particularly known for his experiments that disproved the theory of **spontaneous generation**, firmly establishing microorganisms as the cause of infectious diseases [1]. **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. 23-24.

Question 1370: Which type of necrosis is characterized by deposition of immune complexes and fibrin in the walls of blood vessels?

A. Liquefactive necrosis
B. Coagulative necrosis
C. Caseous necrosis
D. Fibrinoid necrosis (Correct Answer)

Explanation: ***Fibrinoid necrosis*** - This type of necrosis is classically associated with **immune-mediated vascular damage**, where antigen-antibody complexes are deposited in arterial walls [2]. - The microscopic appearance is characterized by bright pink, amorphous material composed of **fibrin and immune complexes**, giving a fibrin-like staining pattern [1]. *Liquefactive necrosis* - Characterized by the **dissolution of dead cells into a viscous liquid mass**, often seen in bacterial infections or brain infarcts. - The necrotic tissue is replaced by inflammatory cells and fluid, rather than immune complex deposits. *Coagulative necrosis* - Occurs due to **ischemia**, leading to protein denaturation and preservation of cell outlines for a period. - It does not involve the deposition of immune complexes or fibrin in vessel walls. *Caseous necrosis* - A form of coagulative necrosis associated with **tuberculosis**, characterized by a friable, "cheese-like" appearance. - It primarily involves granulomatous inflammation and macrophage accumulation, not immune complex deposition in blood vessels. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 514-518. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 214-242.

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