General Pathology Practice Questions

Q: A ring chromosome is a special form of?

Deletion. ### Explanation **1. Why Deletion is the Correct Answer:** A **ring chromosome** is formed when a chromosome undergoes **two terminal deletions** (loss of segments from both the short arm 'p' and long arm 'q'). Following the loss of these telomeric ends, the remaining "sticky" ends of the central segment fuse together to form a ring shape. Because the formation of a ring chromosome necessitates the loss of genetic material from both ends, it is fundamentally a special form of **deletion**. [1] **2. Why Other Options are Incorrect:** * **Inversion:** This involves a single chromosome undergoing two breaks, followed by the 180-degree rotation and reinsertion of the segment. There is no loss of genetic material (balanced rearrangement). [1] * **Isochromosome:** This occurs due to the **horizontal (transverse)** division of the centromere instead of the normal longitudinal division. This results in a chromosome with two identical arms (either two 'p' arms or two 'q' arms). [1] * **Translocation:** This involves the exchange of segments between two non-homologous chromosomes. While it involves breaks, it does not typically result in a circular structure. [1] **3. Clinical Pearls & High-Yield Facts for NEET-PG:** * **Karyotype Notation:** A ring chromosome is denoted by the symbol **'r'** (e.g., 46,XX, r(14) indicates a ring in chromosome 14). * **Clinical Association:** The most common ring chromosome seen in clinical practice is **Ring X**, which is found in some cases of **Turner Syndrome** (45,X/46,X,r(X)). [1] * **Stability:** Ring chromosomes are often unstable during mitosis and may be lost, leading to mosaicism. * **Key Concept:** Remember, "Ring = Two terminal deletions + Fusion." **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 167-177.

Q: Which of the following is NOT a feature of Hand-Schüller-Christian disease?

Enophthalmos.. Hand-Schüller-Christian disease is a chronic disseminated form of **Langerhans Cell Histiocytosis (LCH)**, typically presenting in children. It is characterized by a classic clinical triad that helps differentiate it from other forms of LCH (like Letterer-Siwe disease or Eosinophilic Granuloma). **Why Enophthalmos is the Correct Answer:** The disease is characterized by **Exophthalmos** (protrusion of the eyeball), not enophthalmos (recession of the eyeball). Exophthalmos occurs due to the accumulation of Langerhans cells and granulomatous lesions within the orbital bones or retro-orbital space, which physically displaces the globe forward. **Analysis of Incorrect Options:** * **Punched-out bone destruction:** This is a hallmark radiological feature of LCH. It occurs due to expanding granulomatous lesions in the calvarium (skull), leading to sharply demarcated, non-sclerotic "punched-out" radiolucencies. * **Exophthalmos:** As mentioned, this is a core component of the Hand-Schüller-Christian triad caused by orbital infiltration. * **Diabetes insipidus:** This occurs when the histiocytic infiltration involves the posterior pituitary or the hypothalamus, leading to a deficiency in ADH (Antidiuretic Hormone) [2]. **NEET-PG High-Yield Pearls:** 1. **The Classic Triad:** 1. Punched-out skull defects, 2. Exophthalmos, 3. Diabetes insipidus. 2. **Pathology Markers:** Look for **Birbeck granules** (tennis-racket shaped) on electron microscopy [1] and positivity for **CD1a, S100, and CD207 (Langerin)** on immunohistochemistry [1]. 3. **BRAF Mutation:** Approximately 55% to 60% of LCH cases harbor the **BRAF V600E** mutation [1]. **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. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1084-1085.

Q: A 3-year-old female child presented with skin papules. Which of the following is a marker of Langerhans cell histiocytosis?

CD1a. **Explanation:** Langerhans Cell Histiocytosis (LCH) is a clonal proliferation of Langerhans cells, which are specialized dendritic cells [2]. These cells are characterized by specific immunophenotypic markers and ultrastructural findings. **Why CD1a is correct:** Langerhans cells are antigen-presenting cells that express **CD1a** and **Langerin (CD207)** on their surface [1]. CD1a is a highly specific marker used in immunohistochemistry to confirm the diagnosis of LCH. Additionally, electron microscopy reveals pathognomonic **Birbeck granules** (tennis-racket shaped inclusions), which are associated with the Langerin protein [1]. **Why the other options are incorrect:** * **CD3:** This is a pan-T cell marker. It is used to identify T-lymphocytes and would be negative in histiocytic proliferations. * **CD68:** This is a general marker for macrophages and monocytes. While it may show focal positivity in LCH, it is non-specific and is more characteristic of non-Langerhans cell histiocytoses (like Juvenile Xanthogranuloma). * **CD57:** This is a marker for Natural Killer (NK) cells and certain neuroendocrine tissues; it has no diagnostic role in LCH. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Triad (Hand-Schüller-Christian disease):** Calvarial bone defects, exophthalmos, and diabetes insipidus. * **Common Presentation:** "Cradle cap" like seborrheic dermatitis in infants or punched-out lytic bone lesions (skull). * **Immunophenotype:** Positive for **S100**, **CD1a**, and **Langerin (CD207)** [1]. * **BRAF V600E mutation:** Present in approximately 50% of LCH cases [2]. **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, p. 630. [2] 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 1

Change in structure and functions of a tissue is called:

Accepted Answer

Metaplasia

Answer

Dysplasia

Answer

Anaplasia

Answer

Aplasia

Question 2

A ring chromosome is a special form of?

Accepted Answer

Deletion

Answer

Inversion

Answer

Isochromosome

Answer

Translocation

Question 3

What is apoptosis?

Accepted Answer

Cell death induced by a regulated intracellular program

Answer

Cell survival by a regulated intracellular program

Answer

Modification and adaptation by a regulated intracellular program

Answer

Cell death induced by an extracellular signal

Question 4

A patient is brought to the emergency department following carbon monoxide poisoning. Hyperbaric oxygen was given, following which the patient developed oxygen toxicity. What is the likely mechanism of the toxicity?

Accepted Answer

Mediated by free radicals

Answer

Direct DNA damage

Answer

Apoptosis

Answer

Nuclear fragmentation

Question 5

Which of the following is NOT a feature of Hand-Schüller-Christian disease?

Accepted Answer

Enophthalmos.

Answer

Punched-out bone destruction.

Answer

Exophthalmos.

Answer

Diabetes insipidus.

Question 6

A 3-year-old female child presented with skin papules. Which of the following is a marker of Langerhans cell histiocytosis?

Accepted Answer

CD1a

Answer

CD3

Answer

CD68

Answer

CD57

Question 7

Increased accumulation of fluid in the interstitial space is described as?

Accepted Answer

Edema

Answer

Effusion

Answer

Transudate

Answer

Exudate

Question 8

Which of the following is an example of labile tissue?

Accepted Answer

Transitional epithelium of the urinary tract

Answer

Parenchyma of most solid organs

Answer

Neurons

Answer

Skeletal muscles

Question 9

Which of the following is NOT associated with human papillomavirus infection?

Accepted Answer

Nasopharyngeal carcinoma

Answer

Oropharyngeal tumors

Answer

Anal canal carcinoma

Answer

Cervical carcinoma

Question 10

Pale infarct is seen in all except?

Accepted Answer

Lung

Answer

Liver

Answer

Spleen

Answer

Kidney

General Pathology — MCQs

General Pathology — MCQs

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