Neoplasia — MCQs
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What is used for grading of cancer?
Which of the following is an apoptosis inhibitor gene?
A 59-year-old man complains of progressive weakness and reports very dark stools. Physical examination reveals fullness in the right lower quadrant. Laboratory studies show iron deficiency anemia (serum hemoglobin 7.4 g/dL) and stool occult blood. Colonoscopy discloses an ulcerating lesion of the cecum. Laboratory studies of the surgical specimen demonstrate hypermethylation of the p53 gene in neoplastic cells. Which of the following best characterizes this biochemical change?
All of the following are true about syndrome with microsatellite instability, except?
A 40-year-old tobacco chewer undergoes a routine oral examination. Non-scrapable white patches are noticed on the left buccal mucosa. What histological examination findings are expected?
A 20-year-old man presents with numerous pigmented patches and pedunculated skin tumors. Biopsy of a tumor reveals a benign neoplasm of Schwann cells. The patient has no family history of this condition. The patient is at increased risk of developing which of the following malignant neoplasms?
All of the following are chromosomal breakage syndromes except?
Elevated AFP levels are seen in all of the following conditions, EXCEPT:
Which of the following tumor suppressor genes acts by inhibition of the Hedgehog signaling pathway?
In B-cell lymphoma, which translocation involves the bcl2 gene?
Neoplasia Indian Medical PG Practice Questions and MCQs
Question 581: What is used for grading of cancer?
- A. Differentiation (Correct Answer)
- B. Tumor necrosis
- C. Tumor size
- D. Lymph node status
Explanation: **Explanation:** In oncology, **Grading** and **Staging** are two distinct methods used to evaluate a malignancy. **Why Option A is correct:** **Grading** is a histological assessment of the tumor based on the **degree of differentiation** of the tumor cells and the number of mitoses [1]. Differentiation refers to the extent to which neoplastic cells resemble their normal counterparts (morphologically and functionally) [1]. * **Grade I (Well-differentiated):** Cells closely resemble normal tissue [2]. * **Grade IV (Undifferentiated/Anaplastic):** Cells are primitive and lack resemblance to the tissue of origin [3]. Grading reflects the biological aggressiveness of the tumor. [2] **Why other options are incorrect:** * **Tumor Size (C) and Lymph Node Status (D):** These are components of **Staging** (specifically the TNM system). Staging describes the extent of spread of the cancer within the body. * **Tumor Necrosis (B):** While necrosis can be a feature of high-grade tumors (like Glioblastoma Multiforme), it is a secondary histological feature and not the primary definition of grading across all cancers [2]. **High-Yield Clinical Pearls for NEET-PG:** 1. **Staging vs. Grading:** In most clinical scenarios, **Staging is a better predictor of prognosis** than Grading. 2. **TNM System:** T (Size/Invasion), N (Regional lymph nodes), M (Distant metastasis). 3. **Anaplasia:** The hallmark of malignancy; it represents a total lack of differentiation [3]. 4. **Exceptions:** In some cancers, like Prostate Cancer, the **Gleason Scoring system** (a form of grading) is exceptionally critical for management. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 276-278. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Breast, p. 1068. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 278.
Question 582: Which of the following is an apoptosis inhibitor gene?
- A. p53
- B. Bcl-2 (Correct Answer)
- C. Rb
- D. c-Myc
Explanation: **Explanation:** **Correct Answer: B. Bcl-2** The **Bcl-2** (B-cell lymphoma 2) gene is a classic example of an **anti-apoptotic gene** [1], [3]. It encodes a protein located on the outer mitochondrial membrane that prevents the release of Cytochrome C into the cytosol [3], [4]. By stabilizing the mitochondrial membrane, it inhibits the activation of caspases, thereby preventing programmed cell death (apoptosis) [4]. Overexpression of Bcl-2, often due to the **t(14;18)** translocation, is the hallmark of Follicular Lymphoma [1], [2], [5]. **Incorrect Options:** * **A. p53:** Known as the "Guardian of the Genome," p53 is a tumor suppressor gene that **promotes apoptosis** (via BAX/BAK) if DNA damage is irreparable [3]. * **C. Rb (Retinoblastoma gene):** This is a tumor suppressor gene that regulates the cell cycle at the **G1-S checkpoint**. It does not directly inhibit apoptosis; rather, it prevents uncontrolled cell proliferation by binding to the E2F transcription factor. * **D. c-Myc:** This is a **proto-oncogene** that promotes cell proliferation. While it can drive tumor growth, it is often associated with *pro-apoptotic* signaling if growth factors are deprived [3]. **High-Yield NEET-PG Pearls:** * **Pro-apoptotic members:** BAX, BAK (the "executioners"), and BH3-only proteins (Bim, Bid, Bad) [3]. * **Anti-apoptotic members:** Bcl-2, Bcl-xL, and MCL-1 [3]. * **The "Rheostat" Concept:** The ratio of pro-apoptotic to anti-apoptotic proteins determines whether a cell lives or dies [4]. * **Follicular Lymphoma:** Characterized by **t(14;18)**, which moves the Bcl-2 gene to the Immunoglobulin Heavy chain (IgH) locus, leading to its constitutive overexpression [1], [2], [5]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 310-311. [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. 602-604. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 310. [4] 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. 65-67. [5] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 561-562.
Question 583: A 59-year-old man complains of progressive weakness and reports very dark stools. Physical examination reveals fullness in the right lower quadrant. Laboratory studies show iron deficiency anemia (serum hemoglobin 7.4 g/dL) and stool occult blood. Colonoscopy discloses an ulcerating lesion of the cecum. Laboratory studies of the surgical specimen demonstrate hypermethylation of the p53 gene in neoplastic cells. Which of the following best characterizes this biochemical change?
- A. Epigenetic modification (Correct Answer)
- B. Gene amplification
- C. Insertional mutagenesis
- D. Nonreciprocal translocation
Explanation: ### Explanation **Correct Option: A. Epigenetic Modification** The clinical presentation (elderly male, iron deficiency anemia, and an ulcerating cecal mass) is classic for **Right-sided Colon Cancer**. The question highlights a specific biochemical change: **hypermethylation of the p53 gene** [2]. DNA methylation (specifically at CpG islands in promoter regions) is a form of **epigenetic modification** [1]. Epigenetics refers to heritable changes in gene expression that occur **without altering the primary DNA sequence** [1]. Hypermethylation typically leads to "gene silencing" [4]. In this case, silencing the *p53* tumor suppressor gene removes a critical cell cycle checkpoint, allowing for unregulated neoplastic proliferation [1]. **Why Other Options are Incorrect:** * **B. Gene Amplification:** This involves an increase in the number of copies of a gene (e.g., *HER2/neu* in breast cancer or *N-myc* in neuroblastoma), leading to protein overexpression. It is a genetic, not epigenetic, change. * **C. Insertional Mutagenesis:** This occurs when exogenous DNA (like a retrovirus) integrates into the host genome, disrupting a gene or activating an oncogene. * **D. Nonreciprocal Translocation:** This is a structural chromosomal abnormality where a segment of one chromosome moves to another without a mutual exchange (e.g., *BCR-ABL* in CML is a reciprocal translocation). **NEET-PG High-Yield Pearls:** * **Right-sided vs. Left-sided Colon Cancer:** Right-sided (Cecum) lesions usually present with **occult bleeding and iron deficiency anemia**, whereas left-sided (Sigmoid) lesions present with **"pencil-thin" stools and obstruction**. * **Two Main Pathways of Colorectal Cancer:** 1. **Chromosomal Instability Pathway (Adenoma-Carcinoma sequence):** Involves *APC*, *KRAS*, and *p53* mutations [3]. 2. **Microsatellite Instability (MSI) Pathway:** Involves defects in DNA mismatch repair (MMR) genes (e.g., *MLH1*, *MSH2*) [2]. * **Epigenetic "Hits":** Hypermethylation of the *MLH1* promoter is a common cause of sporadic MSI-high colorectal cancers [2]. **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. 230-231. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 819-821. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 373-374. [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. 213-214.
Question 584: All of the following are true about syndrome with microsatellite instability, except?
- A. DNA repair defects
- B. Autosomal dominant
- C. Increased risk of malignancy
- D. May be associated with immunodeficiency (Correct Answer)
Explanation: This question pertains to **Lynch Syndrome** (Hereditary Non-Polyposis Colorectal Cancer - HNPCC), the classic example of a syndrome characterized by **Microsatellite Instability (MSI)** [1]. ### **Explanation of the Correct Option** **D. May be associated with immunodeficiency (Correct Answer):** Microsatellite instability syndromes, specifically Lynch Syndrome, are caused by defects in the **Mismatch Repair (MMR)** system. Unlike some other DNA repair defects (like Ataxia-Telangiectasia or Wiskott-Aldrich syndrome), Lynch Syndrome is **not** associated with immunodeficiency. Patients have a normal immune response but a significantly increased risk of somatic mutations leading to carcinogenesis. ### **Analysis of Incorrect Options** * **A. DNA repair defects:** This is true. MSI is the hallmark of a defective **DNA Mismatch Repair (MMR)** system (involving genes like *MLH1, MSH2, MSH6,* and *PMS2*) [1]. These genes normally correct "errors" (mismatches) that occur during DNA replication. * **B. Autosomal dominant:** This is true. Lynch Syndrome follows an **Autosomal Dominant** inheritance pattern with high penetrance [1]. * **C. Increased risk of malignancy:** This is true. MSI leads to the accumulation of mutations in growth-regulating genes [1]. It primarily increases the risk of **Colorectal Cancer** (often right-sided) and extracolonic cancers, most notably **Endometrial carcinoma** [1]. ### **NEET-PG High-Yield Pearls** * **The "3-2-1" Rule (Amsterdam Criteria II):** Used for Lynch Syndrome diagnosis—3 relatives with HNPCC-associated cancer, 2 successive generations, 1 diagnosed before age 50. * **Screening:** MSI is detected via PCR; loss of MMR protein expression is detected via Immunohistochemistry (IHC) [1]. * **Prognosis:** Interestingly, MSI-high (MSI-H) colorectal tumors often have a **better prognosis** and better response to immunotherapy (Checkpoint inhibitors like Pembrolizumab) compared to microsatellite stable tumors [1]. * **Common Genes:** *MSH2* and *MLH1* are the most frequently mutated genes in Lynch Syndrome. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 817-821.
Question 585: A 40-year-old tobacco chewer undergoes a routine oral examination. Non-scrapable white patches are noticed on the left buccal mucosa. What histological examination findings are expected?
- A. Normal cells
- B. Dysplastic cells
- C. Aplastic cells
- D. Hyperplastic cells (Correct Answer)
Explanation: ### Explanation **Correct Answer: D. Hyperplastic cells** **Reasoning:** The clinical presentation of "non-scrapable white patches" in a tobacco chewer is classic for **Leukoplakia** [1]. Histologically, leukoplakia is characterized by **Hyperkeratosis** (thickening of the stratum corneum) and **Acanthosis** (hyperplasia of the stratum spinosum). In the early stages of chronic irritation from tobacco, the oral epithelium undergoes compensatory **hyperplasia** to protect the underlying tissue. While leukoplakia is a premalignant condition [1], the most consistent and immediate histological finding in these white patches is an increase in the number of cells (hyperplasia). **Analysis of Incorrect Options:** * **A. Normal cells:** The presence of a visible white patch indicates a pathological change in the epithelium (increased keratinization); therefore, the cells are no longer histologically "normal." * **B. Dysplastic cells:** While leukoplakia *can* show dysplasia (ranging from mild to severe), it is not a universal finding [1]. Only about 5–25% of leukoplakic lesions demonstrate dysplasia on biopsy. Hyperplasia is the more fundamental finding defining the thickened plaque. * **C. Aplastic cells:** Aplasia refers to the failure of an organ or tissue to develop. It is unrelated to the reactive and proliferative changes seen in tobacco-induced oral lesions. **NEET-PG Clinical Pearls:** * **Definition:** Leukoplakia is a clinical term, not a histological one. It is defined by the WHO as "a white patch or plaque that cannot be characterized clinically or pathologically as any other disease" [1]. * **Risk of Malignancy:** Speckled leukoplakia (Erythroleukoplakia) has a much higher risk of malignant transformation into Squamous Cell Carcinoma (SCC) than homogenous white patches. * **Differential Diagnosis:** Oral Candidiasis (thrush) presents as white patches that **can** be scraped off, leaving an erythematous base, unlike leukoplakia [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 344-345. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 737-738.
Question 586: A 20-year-old man presents with numerous pigmented patches and pedunculated skin tumors. Biopsy of a tumor reveals a benign neoplasm of Schwann cells. The patient has no family history of this condition. The patient is at increased risk of developing which of the following malignant neoplasms?
- A. Ganglioneuroma
- B. Glioblastoma multiforme
- C. Neurofibrosarcoma (Correct Answer)
- D. Serous cystadenocarcinoma
Explanation: The clinical presentation of numerous pigmented patches (**Café-au-lait spots**) and pedunculated skin tumors (**Neurofibromas**) in a young patient is diagnostic of **Neurofibromatosis Type 1 (NF1)**, also known as von Recklinghausen disease [2]. Although the patient has no family history, approximately 50% of NF1 cases arise from *de novo* mutations in the *NF1* gene on chromosome 17. **Why Neurofibrosarcoma is correct:** Patients with NF1 have a significantly increased lifetime risk (approximately 5-10%) of developing a **Malignant Peripheral Nerve Sheath Tumor (MPNST)**, also known as **Neurofibrosarcoma** [1]. These typically arise from the malignant transformation of pre-existing plexiform neurofibromas [1]. **Analysis of Incorrect Options:** * **A. Ganglioneuroma:** This is a benign tumor of postganglionic sympathetic neurons. While it belongs to the family of neurogenic tumors, it is not a classic malignant complication of NF1. * **B. Glioblastoma Multiforme (GBM):** While NF1 patients are at risk for CNS tumors, the most characteristic association is **Optic Nerve Glioma** (typically low-grade pilocytic astrocytoma), not GBM. * **D. Serous cystadenocarcinoma:** This is a common malignant ovarian tumor. It is associated with *BRCA1/2* mutations, not the *NF1* mutation. **High-Yield Clinical Pearls for NEET-PG:** * **NF1 (Chromosome 17):** Characterized by Neurofibromas, Café-au-lait spots, **Lisch nodules** (iris hamartomas), and **Axillary freckling** (Crowe sign) [2]. * **NF2 (Chromosome 22):** Characterized by **Bilateral Acoustic Neuromas** (Schwannomas), Meningiomas, and Ependymomas (Mnemonic: *MISME*) [3]. * **Plexiform Neurofibroma:** Pathognomonic for NF1; it carries the highest risk for malignant transformation into Neurofibrosarcoma [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1248-1251. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1248-1249. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 727-728.
Question 587: All of the following are chromosomal breakage syndromes except?
- A. Fanconi's anemia
- B. Ehlers-Danlos syndrome (Correct Answer)
- C. Bloom's syndrome
- D. Ataxia telangiectasia
Explanation: **Explanation:** The correct answer is **Ehlers-Danlos syndrome (EDS)**. **1. Why Ehlers-Danlos syndrome is the correct answer:** Chromosomal breakage syndromes are a group of genetic disorders characterized by **defects in DNA repair mechanisms**, leading to high rates of chromosomal instability and an increased risk of malignancy. **Ehlers-Danlos syndrome**, however, is a group of inherited **connective tissue disorders** caused by defects in the synthesis or structure of **fibrillar collagen** [1]. It does not involve DNA repair defects or chromosomal fragility; rather, it manifests as joint hypermobility, skin hyperextensibility, and tissue fragility [1]. **2. Why the other options are incorrect:** * **Fanconi’s Anemia:** An autosomal recessive disorder involving a defect in the repair of DNA interstrand cross-links [2]. It is characterized by bone marrow failure, radial ray defects, and a high risk of AML. * **Bloom’s Syndrome:** Caused by a mutation in the *BLM* gene (DNA helicase) [2]. It presents with "butterfly" rashes, growth retardation, and a characteristic "sister chromatid exchange" on cytogenetics. * **Ataxia Telangiectasia:** Caused by a mutation in the *ATM* gene, which is responsible for sensing double-strand DNA breaks [2]. It presents with cerebellar ataxia, oculocutaneous telangiectasia, and immunodeficiency. **Clinical Pearls for NEET-PG:** * **Common Feature:** All chromosomal breakage syndromes (including Xeroderma Pigmentosum) carry a significantly **increased risk of cancer** at a young age [2]. * **Diagnostic Test:** Fanconi’s anemia is diagnosed using the **Diepoxybutane (DEB) test** or Mitomycin C test to induce chromosomal breaks. * **Inheritance:** Most chromosomal breakage syndromes are **Autosomal Recessive**. * **EDS High-Yield:** Type IV (Vascular type) is associated with *COL3A1* mutations and carries a risk of arterial or bowel rupture. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 154-155. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 322-323.
Question 588: Elevated AFP levels are seen in all of the following conditions, EXCEPT:
- A. Hepatoblastoma (Correct Answer)
- B. Seminoma
- C. Teratoma
- D. None of the above
Explanation: **Explanation:** Alpha-Fetoprotein (AFP) is a glycoprotein normally produced by the fetal liver and yolk sac. In adult pathology, it serves as a crucial tumor marker for specific germ cell tumors and hepatocellular carcinomas. **Why Hepatoblastoma is the "Correct" Answer (Contextual Note):** There appears to be a discrepancy in the provided key. **Hepatoblastoma** is actually characterized by **markedly elevated AFP** (seen in over 90% of cases) [1]. If the question asks for the condition where AFP is *NOT* elevated, the correct answer should typically be **Seminoma**. Pure seminomas are notorious for having normal AFP levels [3]; if AFP is elevated in a suspected seminoma, it indicates the presence of a non-seminomatous component (like a Yolk Sac tumor). **Analysis of Options:** * **Hepatoblastoma:** This is the most common primary liver tumor in children [1]. It is strongly associated with very high serum AFP levels, which are used for both diagnosis and monitoring treatment response. * **Seminoma:** Pure seminomas **do not** produce AFP [3]. They may show elevated hCG (in 10-15% of cases due to syncytiotrophoblasts), but elevated AFP excludes a diagnosis of pure seminoma [3]. * **Teratoma:** While pure mature teratomas may not raise AFP, clinical "teratomas" in the testes are often mixed germ cell tumors [2], [4]. However, in a strict academic sense, AFP is the hallmark of **Yolk Sac Tumors**. **High-Yield Clinical Pearls for NEET-PG:** 1. **Yolk Sac Tumor (Endodermal Sinus Tumor):** The most specific marker is **AFP**. Look for **Schiller-Duval bodies** on histology. 2. **Hepatocellular Carcinoma (HCC):** AFP is used for screening high-risk (cirrhotic) patients. 3. **Neural Tube Defects (NTD):** Elevated AFP in maternal serum/amniotic fluid indicates NTDs (e.g., Anencephaly, Spina bifida), while **decreased** AFP is associated with **Down Syndrome**. 4. **Rule of Thumb:** If AFP is elevated in a testicular biopsy labeled "Seminoma," the diagnosis must be changed to a **Mixed Germ Cell Tumor** [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Liver and Gallbladder, pp. 875-876. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 512-513. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lower Urinary Tract and Male Genital System, pp. 980-982. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lower Urinary Tract and Male Genital System, pp. 982-983.
Question 589: Which of the following tumor suppressor genes acts by inhibition of the Hedgehog signaling pathway?
- A. PTCH (Correct Answer)
- B. SDHB
- C. BRCA1
- D. CDKN2A
Explanation: **Explanation:** The **PTCH1 (Patched)** gene is a classic tumor suppressor gene that encodes a transmembrane receptor which acts as a negative regulator of the **Hedgehog (Hh) signaling pathway** [1]. In its normal state, PTCH1 inhibits **SMO (Smoothened)**, a protein that triggers downstream oncogenic signaling [2]. When a Hedgehog ligand (like Sonic Hedgehog) binds to PTCH1, or if PTCH1 is mutated/lost, the inhibition on SMO is lifted [1], [2]. This leads to the activation of GLI transcription factors, promoting cell proliferation and survival [2]. **Analysis of Options:** * **PTCH (Correct):** Germline mutations in *PTCH1* are the hallmark of **Gorlin Syndrome** (Nevoid Basal Cell Carcinoma Syndrome), characterized by multiple basal cell carcinomas, odontogenic keratocysts, and medulloblastomas [3]. * **SDHB:** Encodes a subunit of Succinate Dehydrogenase (Mitochondrial Complex II). Mutations are associated with familial **pheochromocytoma and paraganglioma** syndromes, acting through metabolic reprogramming (pseudohypoxia). * **BRCA1:** A DNA repair gene involved in **homologous recombination**. Mutations lead to genomic instability, primarily predisposing to breast and ovarian cancers. * **CDKN2A:** Encodes two critical cell cycle regulators: **p16/INK4a** (inhibits CDK4/6) and **p14/ARF** (stabilizes p53). It is frequently mutated in melanoma and pancreatic cancer. **High-Yield Clinical Pearls for NEET-PG:** * **Gorlin Syndrome Triad:** Multiple BCCs + Odontogenic Keratocysts (OKC) + Calcification of Falx Cerebri [3]. * **Targeted Therapy:** **Vismodegib** is a small-molecule inhibitor of SMO used to treat advanced Basal Cell Carcinoma by pharmacologically mimicking the inhibitory function of PTCH [1]. * **Hedgehog Pathway** is also crucial in embryogenesis; its dysregulation can lead to holoprosencephaly. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 306-307. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1158-1160. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1157-1158.
Question 590: In B-cell lymphoma, which translocation involves the bcl2 gene?
- A. t(8:14)
- B. t(8:12)
- C. t(14:18) (Correct Answer)
- D. t(14:22)
Explanation: **Explanation:** The correct answer is **t(14:18)**, which is the hallmark translocation of **Follicular Lymphoma**, a common type of B-cell non-Hodgkin lymphoma [1]. **1. Why t(14:18) is correct:** In this translocation, the ***BCL2* gene** on chromosome 18 is moved to the **Immunoglobulin Heavy chain (IgH) locus** on chromosome 14 [1], [2]. Because the IgH promoter is highly active in B-cells, this results in the massive over-expression of the BCL2 protein [3]. BCL2 is an **anti-apoptotic** protein that stabilizes the mitochondrial membrane; its over-expression prevents programmed cell death, leading to the accumulation of neoplastic B-cells [1], [3]. **2. Analysis of Incorrect Options:** * **t(8:14):** This involves the ***c-MYC* oncogene** (Ch 8) and the IgH locus (Ch 14) [4]. It is the characteristic translocation of **Burkitt Lymphoma**, leading to rapid cellular proliferation [4]. * **t(8:12) and t(14:22):** These are not standard high-yield translocations associated with B-cell lymphomas in the NEET-PG curriculum. (Note: t(11:14) is the translocation for Mantle Cell Lymphoma involving *Cyclin D1*). **3. NEET-PG High-Yield Pearls:** * **Follicular Lymphoma:** Presents with painless "waxing and waning" lymphadenopathy. Histology shows back-to-back follicles lacking tingible body macrophages [1]. * **BCL2** is the "survival factor." Its presence in follicles on immunohistochemistry (IHC) helps differentiate Follicular Lymphoma (BCL2 positive) from reactive follicular hyperplasia (BCL2 negative) [1]. * **Mnemonic:** "14:18" – The **B**cl-**2** gene is on chromosome **18** (B is the 2nd letter, 18+2=20; or simply associate '18' with 'B'cl2). **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. 602-604. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 310-311. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 561-562. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 324-325.
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