General Pathology — MCQs

A 29-year-old man sustains a left femoral fracture in a motorcycle accident. His leg is placed in a plaster cast. After his left leg has been immobilized for 6 weeks, the diameter of the left calf has decreased in size. This change in size is most likely to result from which of the following alterations in his calf muscles?

Q1349

Fat necrosis is common in:

Q1350

Term "Pseudo" used in "Pseudocyst" is due to its -

General Pathology Indian Medical PG Practice Questions and MCQs

Question 1341: Which of these is a pseudocyst:

A. Nasolabial cyst
B. Traumatic cyst (Correct Answer)
C. Globulomaxillary cyst
D. Radicular cyst

Explanation: ***Traumatic cyst*** - A **traumatic cyst** (also known as a **solitary bone cyst** or **simple bone cyst**) lacks an **epithelial lining**, which is the defining characteristic of a pseudocyst [1]. - These cysts are typically associated with **trauma** and are filled with serosanguineous fluid or may be empty, often found in the jaws or long bones. - The cavity wall is composed of connective tissue without any epithelial lining [1]. *Nasolabial cyst* - A **nasolabial cyst** is a **true cyst** because its lumen is lined by **stratified squamous or pseudostratified columnar epithelium**. - It is a soft tissue cyst located at the junction of the ala of the nose and the upper lip. *Globulomaxillary cyst* - The globulomaxillary cyst is now regarded as a **misnomer**; similar lesions are identified as **odontogenic cysts**, typically a **radicular cyst** or **keratocystic odontogenic tumor**. - These are **true cysts** with an epithelial lining, originating from odontogenic epithelial rests. *Radicular cyst* - A **radicular cyst** is a **true cyst** arising from epithelial rests of Malassez in response to inflammation from a non-vital tooth. - It is histologically characterized by a **lumen lined with stratified squamous epithelium**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Pancreas, p. 895.

Question 1342: Radiation-induced necrosis can be diagnosed by:

A. MRI
B. CT
C. PET
D. Biopsy (Correct Answer)

Explanation: ***Biopsy*** - A **biopsy** is the definitive diagnostic method for radiation-induced necrosis, allowing for histological examination of tissue to confirm necrosis and rule out residual or recurrent tumor. [1], [2] - It provides a direct view of cellular changes, identifying **necrosis, atypical cells**, and ruling out **malignancy**. *MRI* - While **MRI** can show structural changes indicative of necrosis (e.g., mass effect, edema), it often cannot definitively differentiate between **radiation necrosis** and **tumor recurrence.** [2] - It often shows **T1 hypointensity** and **T2 hyperintensity**, but these findings are not specific. *CT* - **CT scans** are useful for detecting gross changes like **mass effect** and **edema** but have limited sensitivity for distinguishing necrosis from tumor recurrence. - It may show **low-density lesions** but lacks the resolution and specificity for precise diagnosis. *PET* - **PET scans** measure metabolic activity and can help distinguish between **tumor recurrence** (high uptake) and **radiation necrosis** (low uptake) in some cases. - However, false positives can occur, as some inflammatory processes in necrosis can also show increased uptake, making it **less definitive** than a biopsy. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1307-1308. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 340-341.

Question 1343: Cells are most sensitive to ionizing radiation during which phase?

A. S phase
B. G2M phase (Correct Answer)
C. G0 phase
D. G1 phase

Explanation: ***G2M phase*** - Cells are most sensitive to ionizing radiation during the **G2 phase** and **M phase** (mitosis) due to the highly condensed chromatin structure and active DNA repair mechanisms being less efficient [2], [3]. - During G2, DNA synthesis is complete, and the cell is preparing for division, making DNA damage particularly detrimental and harder to repair without compromising cell viability [2]. *S phase* - Cells in the **S phase** (DNA synthesis phase) are relatively radioresistant because of active **DNA replication** and associated repair mechanisms. - These repair pathways are highly efficient at correcting DNA damage during replication, making the cell less susceptible to radiation-induced lethality. *G1 phase* - Cells in the **G1 phase** (first gap phase) show intermediate radiosensitivity. - While less sensitive than G2/M phases, G1 cells are more vulnerable than those in late S phase due to active metabolic preparation for DNA synthesis [1]. *G0 phase* - Cells in the **G0 phase** (quiescent phase) are generally **radioresistant** because they are not actively dividing or synthesizing DNA [3]. - They have ample time for DNA repair before re-entering the cell cycle, and their DNA structure is less vulnerable than during active division [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 302-303. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. With Illustrations By, pp. 37-38. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Central Nervous System Synapse, pp. 436-437.

Question 1344: Phase-contrast microscopy is based on the principle of:

A. Phase differences of light (Correct Answer)
B. Light attenuation
C. Light scattering
D. Different refractive indices of object

Explanation: ***Phase differences of light*** - Phase-contrast microscopy converts small **phase shifts** in light passing through a transparent specimen into changes in **brightness** or contrast. - This allows the visualization of unstained, transparent specimens without damaging them. *Light attenuation* - Light attenuation refers to the **reduction in light intensity** as it passes through a medium due to absorption or scattering. - While some light attenuation occurs, it is not the primary principle by which phase-contrast microscopy generates images. *Light scattering* - Light scattering is the process by which light is **diverted from its original path** due to interaction with particles in the medium. - While scattering can contribute to image formation in some microscopic techniques, phase-contrast microscopy primarily relies on phase shifts rather than scattering. *Different refractive indices of object* - While different refractive indices of an object cause the **phase shifts** that phase-contrast microscopy exploits, stating "different refractive indices of object" alone is an incomplete description of the underlying principle. - The technique specifically visualizes these **phase differences** that result from varying refractive indices, converting them into amplitude differences.

Question 1345: Which of the following is most specific for CSF in rhinorrhea?

A. Albumin
B. Macroglobulin
C. Beta-2 transferrin (Correct Answer)
D. Beta-2 microglobulin

Explanation: ***b-2 transferrin*** - **Beta-2 transferrin** is a desialylated form of transferrin found almost exclusively in **cerebrospinal fluid (CSF)**, perilymph, and aqueous humor. - Its presence in nasal discharge is highly **specific** for the diagnosis of CSF rhinorrhea, as it is not typically found in serum or other bodily secretions. *Albumin* - **Albumin** is abundant in both serum and CSF, so its presence in nasal discharge is not specific for CSF and could indicate the presence of blood or inflammatory exudates. - Measuring albumin levels alone would not reliably differentiate CSF rhinorrhea from other types of nasal discharge. *Macroglobulin* - **Alpha-2 macroglobulin** is a large plasma protein primarily found in **blood**, not typically in significant concentrations in CSF. - Its presence would be more indicative of serum contamination rather than CSF leakage. *b-2 microglobulin* - **Beta-2 microglobulin** is a protein found on the surface of most nucleated cells and is present in various body fluids including **serum** and **CSF**, though usually in higher concentrations in conditions associated with inflammation or malignancy. - While present in CSF, it is not specific enough to reliably distinguish CSF rhinorrhea from other types of nasal discharge, especially if blood is also present.

Question 1346: Coffee bean nuclei are seen in all of the following except:

A. Granulosa cell tumor
B. Langerhans cell histiocytosis
C. Brenner tumor
D. Follicular carcinoma thyroid (Correct Answer)

Explanation: ***Follicular carcinoma thyroid*** - **Follicular carcinoma** is characterized by uniform follicular cells, with features like **nuclear grooves** and **intranuclear pseudoinclusions** being more typical of **papillary thyroid carcinoma**, not follicular. - The nuclei in follicular carcinoma do not typically exhibit the characteristic **longitudinal grooves** resembling "coffee beans" seen in some other tumors. *Granulosa cell tumor* - **Granulosa cell tumors** are ovarian stromal tumors often characterized by **longitudinal nuclear grooves**, giving the appearance of **"coffee bean" nuclei**. - These grooves are a key diagnostic feature, along with structures like **Call-Exner bodies**. *Langerhans cell histiocytosis* - Cells in **Langerhans cell histiocytosis** are large, mononuclear cells with abundant cytoplasm and distinctive **grooved or reniform nuclei**, often described as **"coffee bean" shaped** [1]. - These nuclear grooves are a hallmark feature, visible on electron microscopy as **Birbeck granules** [1]. *Brenner tumor* - **Brenner tumors** are ovarian tumors that can arise from transitional cell nests and often feature prominent **nuclear grooves** in their epithelial cells. - These grooves can appear as **"coffee bean" nuclei**, particularly in the spindle cell variant or solid areas of the tumor. **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 1347: Radiation causes cell death by:

A. Charring of nucleoproteins
B. Ionization (Correct Answer)
C. Disruption of cytosol
D. Destroying their mitochondria

Explanation: ***Ionization*** - Radiation, particularly **ionizing radiation**, causes cell death by directly or indirectly damaging cellular components through the process of **ionization**. [1] - This involves the removal of electrons from atoms or molecules, leading to the formation of highly reactive **free radicals** (especially hydroxyl radicals from water radiolysis) that can damage DNA, proteins, and lipids. [1] - The most critical lethal lesion is **DNA double-strand breaks**, which are difficult to repair and trigger apoptosis or mitotic catastrophe. [1] *Charring of nucleoproteins* - **Charring** typically refers to the combustion or burning of organic matter, which is not the mechanism of cell death caused by therapeutic radiation doses. - While radiation can cause protein denaturation, it does not lead to the macroscopic charring of nucleoproteins within cells. *Disruption of cytosol* - While severe radiation damage can impact the entire cell, direct and selective **disruption of the cytosol** is not the primary or most impactful mechanism of radiation-induced cell death. - The critical targets for radiation-induced cell death are primarily the **nucleus** and its DNA, not the cytoplasm. [2] *Destroying their mitochondria* - Although radiation can induce **mitochondrial dysfunction** and contribute to cell death through apoptosis, it is not the initial or primary mechanism of cell destruction. - The most critical and direct damage leading to cell death is inflicted upon the **DNA** in the nucleus, particularly causing double-strand breaks. [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. 100-102. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Central Nervous System Synapse, pp. 438-439.

Question 1348: A 29-year-old man sustains a left femoral fracture in a motorcycle accident. His leg is placed in a plaster cast. After his left leg has been immobilized for 6 weeks, the diameter of the left calf has decreased in size. This change in size is most likely to result from which of the following alterations in his calf muscles?

A. Hyalinosis
B. Dystrophy
C. Aplasia
D. Atrophy (Correct Answer)

Explanation: ***Atrophy*** - **Muscle atrophy** refers to the decrease in muscle mass due to disuse, denervation, or other pathological conditions [1]. In this case, prolonged **immobilization** of the leg in a cast leads to disuse of the calf muscles, resulting in a reduction in their size and strength [1]. - This process involves a decrease in the size of individual muscle cells and a reduction in the number of contractile proteins, such as **actin** and **myosin**, within these cells [1]. *Hyalinosis* - **Hyalinosis** is a process characterized by the accumulation of a glassy, homogeneous, eosinophilic material (hyaline) in tissues, often associated with degenerative changes. - It does not directly explain the specific reduction in muscle bulk due to immobilization; rather, it describes a type of degenerative change within cells or extracellular spaces. *Dystrophy* - **Muscular dystrophy** refers to a group of genetic diseases characterized by progressive weakness and degeneration of muscle fibers [2]. - It is a primary muscle disorder with a genetic basis, distinct from disuse-induced muscle wasting, and would not typically manifest as a result of temporary immobilization [2]. *Aplasia* - **Aplasia** is the failure of an organ or tissue to develop or to be completely formed. - This term is used to describe a congenital condition where a structure is completely absent or severely underdeveloped from birth, which is not applicable to a previously normal muscle decreasing in size after injury. **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. Peripheral Nerves and Skeletal Muscles, pp. 1244-1245.

Question 1349: Fat necrosis is common in:

A. Breast (Correct Answer)
B. Retroperitoneal fat
C. Omentum
D. All of the options

Explanation: ***Breast*** - **Fat necrosis** in the breast is a relatively common benign condition, often resulting from trauma, surgery, or radiation. - It presents as a palpable lump that can mimic malignancy, making its differentiation crucial. *Retroperitoneal fat* - While fat necrosis can occur in the retroperitoneum, particularly in cases of **acute pancreatitis**, it is not considered "common" in this location independently [1]. - The primary tissue affected in pancreatitis is the pancreas itself, with necrosis extending to surrounding fat [1]. *Omentum* - **Omental fat necrosis** can occur but is rare and usually associated with torsion of the omentum or, less commonly, blunt abdominal trauma. - It is not a common site for isolated fat necrosis compared to the breast. *All of the options* - Although fat necrosis can occur in all these locations under specific circumstances, it is not "common" in all of them when considering the typical incidence of the condition. - **Breast fat necrosis** is more frequently encountered in clinical practice than in the omentum or retroperitoneal region. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Pancreas, p. 895.

Question 1350: Term "Pseudo" used in "Pseudocyst" is due to its -

A. Lining (Correct Answer)
B. Site
C. Course
D. Contents

Explanation: ***Lining*** - A **pseudocyst** lacks an **epithelial or endothelial lining**, which is characteristic of true cysts [1]. - Instead, its wall is formed by **fibrous tissue** and **granulation tissue** surrounding fluid collections [1]. *Site* - The term "pseudo" does not refer to the **location** of the cyst. - Pseudocysts commonly occur in specific organs like the **pancreas**, but their site is not what defines them as "pseudo" [1]. *Course* - The **clinical course** or progression of a pseudocyst, whether it resolves spontaneously or requires intervention, is not the basis for the "pseudo" designation [1]. - Its behavior, while clinically important, does not define its fundamental nature. *Contents* - The contents of a pseudocyst, which often include **necrotic debris**, **inflammatory fluid**, or **pancreatic enzymes**, do not define the "pseudo" aspect. - The fluid composition is a result of the underlying condition, not the reason for the term "pseudo." **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Pancreas, p. 895.

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