Neoplasia — MCQs
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All of the following may be associated with Von Hippel-Lindau syndrome, except?
Which of the following malignancies is not associated with elevated alpha-fetoprotein (AFP)?
In MEN syndromes 2A and 2B, which growth factor receptor shows a point mutation?
A 40-year-old man with a history of intravenous drug use and positive serologic studies for HBsAg and anti-HCV develops hepatocellular carcinoma 15 years later. Physical examination shows needle tracks in his left antecubital fossa and mild scleral icterus. Which of the following viral characteristics best explains the development of hepatocellular carcinoma?
Which of the following is a marker for testicular tumor?
Which mutation is commonly seen in malignant melanoma?
In pleomorphic adenoma, which gene mutation occurs?
A 65-year-old man complains of muscle weakness and a dry cough for 4 months. He has smoked two packs of cigarettes daily for 45 years. A chest X-ray shows a 4-cm central, left lung mass. Laboratory studies reveal hyperglycemia and hypertension. A transbronchial biopsy is diagnosed as small cell carcinoma. Metastases to the liver are detected by CT scan. Which of the following might account for the development of hyperglycemia and hypertension in this patient?
Paraneoplastic erythrocytosis is most commonly seen in which malignancy?
Which type of sarcoma is commonly seen in infancy?
Neoplasia Indian Medical PG Practice Questions and MCQs
Question 431: All of the following may be associated with Von Hippel-Lindau syndrome, except?
- A. Retinal and cerebellar hemangioblastomas
- B. Gastric carcinoma (Correct Answer)
- C. Pheochromocytoma
- D. Renal cell carcinoma
Explanation: **Explanation:** **Von Hippel-Lindau (VHL) syndrome** is an autosomal dominant multisystem disorder caused by a mutation in the **VHL tumor suppressor gene** located on **chromosome 3p25**. The VHL protein normally degrades Hypoxia-Inducible Factor (HIF-1α); its loss leads to an overaccumulation of HIF, resulting in the overexpression of angiogenic growth factors like VEGF. **Why Gastric Carcinoma is the correct answer:** Gastric carcinoma is **not** a component of VHL syndrome [2]. While VHL is associated with various visceral cysts and tumors (especially in the pancreas, kidneys, and reproductive tract), it does not predispose patients to gastric malignancies. Gastric cancer is more commonly associated with syndromes like Hereditary Diffuse Gastric Cancer (CDH1 mutation) or Lynch syndrome. **Analysis of Incorrect Options:** * **Retinal and cerebellar hemangioblastomas:** These are the hallmark lesions of VHL [1]. Retinal hemangioblastomas (angiomatosis retinae) often present with visual loss, while cerebellar lesions present with ataxia or increased intracranial pressure. * **Pheochromocytoma:** VHL Type 2 is specifically characterized by a high risk of pheochromocytomas [1], which are often bilateral or multifocal. * **Renal cell carcinoma (RCC):** Patients have a significantly high risk (up to 70%) of developing **clear cell RCC**, which is often bilateral and multicentric [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic (HIPPEL):** **H**emangioblastomas, **I**slet cell tumors (Pancreas), **P**heochromocytoma, **P**ancreatic cysts, **E**ndolymphatic sac tumors, **L**ocus (Chromosome 3). * **VHL Gene:** Also mutated in the majority of **sporadic** clear cell renal carcinomas. * **Cause of Death:** The most common causes of mortality in VHL patients are RCC and cerebellar hemangioblastomas. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, p. 1137. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 776-777.
Question 432: Which of the following malignancies is not associated with elevated alpha-fetoprotein (AFP)?
- A. Hepatoblastoma
- B. Carcinoma of the colon
- C. Embryonal cell carcinoma
- D. Seminoma (Correct Answer)
Explanation: **Explanation:** **Alpha-fetoprotein (AFP)** is a glycoprotein normally produced by the fetal liver and yolk sac. In adults, it serves as a crucial tumor marker for specific germ cell tumors and hepatobiliary malignancies [2]. **Why Seminoma is the correct answer:** Seminoma is a "pure" germ cell tumor. By definition, **pure seminomas do not produce AFP.** If a patient clinically diagnosed with a seminoma shows elevated AFP levels, it indicates the presence of a **mixed germ cell tumor** containing yolk sac components [4]. However, seminomas can occasionally show mild elevations of hCG (if syncytiotrophoblasts are present), but never AFP [3]. **Analysis of Incorrect Options:** * **Hepatoblastoma:** This is the most common liver tumor in children [1]; AFP is significantly elevated in over 90% of cases and is used for both diagnosis and monitoring treatment response. * **Carcinoma of the Colon:** While CEA (Carcinoembryonic Antigen) is the primary marker for colorectal cancer, AFP can be elevated in rare variants like **Hepatoid Adenocarcinoma of the colon** or in cases with liver metastasis. * **Embryonal Cell Carcinoma:** This is a non-seminomatous germ cell tumor (NSGCT). It frequently presents as a mixed tumor; when it contains yolk sac elements, AFP levels rise [4]. **High-Yield Clinical Pearls for NEET-PG:** * **Yolk Sac Tumor (Endodermal Sinus Tumor):** This is the classic tumor associated with the **highest** levels of AFP. Look for "Schiller-Duval bodies" on histology. * **Hepatocellular Carcinoma (HCC):** AFP is the screening marker of choice. A level >400 ng/mL in a high-risk patient (e.g., Cirrhosis/HBV) is highly suggestive [2]. * **Neural Tube Defects (NTD):** In maternal screening, elevated AFP in amniotic fluid/serum suggests NTDs (e.g., Spina bifida), while low AFP is associated with **Down Syndrome**. **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 Liver And Biliary System Disease, pp. 399-400. [3] 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. [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. 979-983.
Question 433: In MEN syndromes 2A and 2B, which growth factor receptor shows a point mutation?
- A. TP53
- B. RET (Correct Answer)
- C. KIT
- D. MSH 2
Explanation: **Explanation:** The correct answer is **RET**. Multiple Endocrine Neoplasia (MEN) syndromes 2A and 2B are caused by germline **gain-of-function point mutations** [3] in the **RET proto-oncogene**, located on chromosome 10q11.2 [1]. The RET gene encodes a **receptor tyrosine kinase** involved in cell signaling for growth and differentiation [2]. In MEN 2, these mutations lead to constitutive activation of the receptor, driving the development of Medullary Thyroid Carcinoma (MTC), Pheochromocytoma, and other associated tumors [3]. **Analysis of Incorrect Options:** * **TP53 (Option A):** This is a tumor suppressor gene (the "Guardian of the Genome"). Mutations are associated with **Li-Fraumeni Syndrome** and a vast majority of sporadic human cancers, but not specifically MEN 2. * **KIT (Option C):** This encodes a receptor tyrosine kinase (CD117). Mutations in KIT are classically associated with **Gastrointestinal Stromal Tumors (GIST)** and Mastocytosis [4]. * **MSH 2 (Option D):** This is a DNA mismatch repair (MMR) gene. Mutations lead to microsatellite instability, characteristic of **Lynch Syndrome** (Hereditary Non-Polyposis Colorectal Cancer). **High-Yield Clinical Pearls for NEET-PG:** * **MEN 2A (Sipple Syndrome):** Medullary Thyroid Carcinoma + Pheochromocytoma + Parathyroid Hyperplasia [1]. * **MEN 2B (Wagenmann-Froboese):** Medullary Thyroid Carcinoma + Pheochromocytoma + Mucosal Neuromas + Marfanoid Habitus [1]. * **Prophylactic Thyroidectomy:** Because of the high penetrance of MTC in RET mutation carriers, prophylactic removal of the thyroid is often indicated in early childhood. * **Hirschsprung Disease:** While gain-of-function RET mutations cause MEN 2, **loss-of-function** mutations in the same gene are associated with Hirschsprung disease. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, p. 1137. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1097-1098. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 292. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 782-783.
Question 434: A 40-year-old man with a history of intravenous drug use and positive serologic studies for HBsAg and anti-HCV develops hepatocellular carcinoma 15 years later. Physical examination shows needle tracks in his left antecubital fossa and mild scleral icterus. Which of the following viral characteristics best explains the development of hepatocellular carcinoma?
- A. Viral integration in the vicinity of proto-oncogenes
- B. Viral capture of proto-oncogenes from host cellular DNA
- C. Viral inflammatory changes with genomic damage (Correct Answer)
- D. Viral inactivation of RB and p53 gene expression
Explanation: **Explanation:** The development of hepatocellular carcinoma (HCC) in the setting of chronic Hepatitis B (HBV) and Hepatitis C (HCV) is primarily driven by **chronic inflammation and compensatory regeneration** [1]. **1. Why Option C is Correct:** Unlike many other oncogenic viruses, HBV and HCV do not possess a dominant oncogene. Instead, the persistent immune-mediated destruction of hepatocytes leads to a cycle of **chronic inflammation, cell death, and compensatory regeneration** [1]. This high turnover rate increases the likelihood of spontaneous mutations. Furthermore, the inflammatory milieu produces **reactive oxygen species (ROS)**, which cause direct genomic damage and promote the accumulation of mutations in genes like *TP53* and *CTNNB1* (β-catenin). **2. Analysis of Incorrect Options:** * **Option A:** While HBV can integrate into the host genome, it does so randomly [1]. There is no consistent evidence that it specifically integrates near proto-oncogenes (insertional mutagenesis) as a primary mechanism for HCC. HCV, being an RNA virus, does not integrate into the host DNA at all. * **Option B:** This describes the mechanism of "transducing" retroviruses (e.g., Rous Sarcoma Virus), which is not the mechanism for HBV or HCV. * **Option D:** This is the classic mechanism for **High-risk HPV** (E6 inhibits p53; E7 inhibits RB). While the HBV-encoded **HBx protein** can interfere with p53, it is not the dominant pathway compared to the inflammatory-regenerative cycle [1], [3]. **Clinical Pearls for NEET-PG:** * **HBV vs. HCV:** HBV is a DNA virus; HCV is an RNA virus. Both are major risk factors for HCC [2]. * **Aflatoxin B1:** A potent co-carcinogen for HCC (found in *Aspergillus* on stored grains) that causes a specific mutation in **codon 249 of the TP53 gene** [2]. * **Tumor Marker:** Elevated **Alpha-fetoprotein (AFP)** is a high-yield screening marker for HCC. * **Cirrhosis:** The strongest clinical predictor of HCC; most cases of HCC (especially HCV-related) arise in a cirrhotic liver [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 336-337. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Liver and Gallbladder, pp. 876-877. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Liver and Gallbladder, pp. 838-840.
Question 435: Which of the following is a marker for testicular tumor?
- A. Beta hCG (Correct Answer)
- B. Acid phosphatase
- C. Alkaline phosphatase
- D. Alpha fetoprotein
Explanation: Testicular germ cell tumors (GCTs) often secrete specific serum biomarkers that are crucial for diagnosis, staging, and monitoring treatment response. **Beta-hCG (Human Chorionic Gonadotropin)** is the correct answer because it is a classic marker for GCTs containing **syncytiotrophoblasts** [1]. It is most significantly elevated in **Choriocarcinoma** (100% of cases) [2] and is also elevated in about 10-15% of pure Seminomas [4]. **Analysis of Incorrect Options:** * **Acid phosphatase:** Specifically, Prostatic Acid Phosphatase (PAP) was historically used as a marker for **Prostate Cancer**, though it has largely been replaced by PSA. * **Alkaline phosphatase:** While the Placental-like isoform (PLAP) can be elevated in Seminomas [4], "Alkaline phosphatase" generally refers to the liver/bone isoenzyme, which is non-specific. * **Alpha-fetoprotein (AFP):** While AFP is a major marker for **Yolk Sac Tumors** and Embryonal Carcinomas, it is **never** elevated in pure Seminomas [4]. In the context of this specific question format, Beta-hCG is the most definitive marker associated with the general category of GCTs. **High-Yield Clinical Pearls for NEET-PG:** * **Seminoma:** Most common GCT; Marker = **PLAP** (most sensitive), Beta-hCG (in 10-15% cases) [4]. **AFP is always normal.** * **Yolk Sac Tumor:** Most common testicular tumor in infants; Marker = **AFP** (Schiller-Duval bodies on histology) [3]. * **Choriocarcinoma:** Most aggressive; Marker = **Very high Beta-hCG** [2]. * **LDH (Lactate Dehydrogenase):** Used as a non-specific marker to assess tumor burden and prognosis in GCTs. **References:** [1] 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. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lower Urinary Tract and Male Genital System, p. 982. [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. 979-980. [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. 980-982.
Question 436: Which mutation is commonly seen in malignant melanoma?
- A. P53
- B. CDKN2A (Correct Answer)
- C. RET
- D. Rb
Explanation: **Explanation:** **Malignant Melanoma** is a highly aggressive skin cancer arising from melanocytes [1]. The most common germline mutation associated with familial melanoma is the **CDKN2A** gene, located on chromosome 9p21 [1]. 1. **Why CDKN2A is Correct:** CDKN2A is a critical tumor suppressor gene that encodes two proteins via alternative splicing: **p16/INK4a** (which inhibits CDK4/6, maintaining the Rb protein in its active hypophosphorylated state) and **p14/ARF** (which prevents p53 degradation) [1]. Mutations in CDKN2A lead to the loss of control over both the Rb and p53 pathways, promoting unregulated cell cycle progression [1]. It is mutated in approximately 40% of familial melanomas and is also frequently inactivated in sporadic cases. 2. **Analysis of Incorrect Options:** * **P53 (TP53):** While p53 is the most common mutation in human cancers overall (especially Squamous Cell Carcinoma), it is typically a late-stage event in melanoma rather than the primary driver mutation. * **RET:** This proto-oncogene is characteristically associated with **Multiple Endocrine Neoplasia (MEN) 2A and 2B**, as well as Medullary Thyroid Carcinoma and Papillary Thyroid Carcinoma. * **Rb:** Mutations in the Retinoblastoma gene are classically linked to **Retinoblastoma** and **Osteosarcoma**. While the Rb *pathway* is affected in melanoma (via p16), the direct mutation of the Rb gene itself is not the primary feature [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Most common sporadic mutation:** **BRAF (V600E)** is seen in ~50-60% of melanomas (Targeted therapy: Vemurafenib) [1]. * **Radial Growth Phase:** Melanoma grows horizontally within the epidermis (Good prognosis). * **Vertical Growth Phase:** Melanoma invades the dermis; the **Breslow Thickness** (measured in mm) is the most important prognostic factor [1]. * **ABCDE Criteria:** Asymmetry, Border irregularity, Color variation, Diameter >6mm, Evolving. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1150-1153.
Question 437: In pleomorphic adenoma, which gene mutation occurs?
- A. PLAG1 gene (Correct Answer)
- B. PLAM1 gene
- C. PLAG2 gene
- D. All of the above
Explanation: **Explanation:** **Pleomorphic Adenoma** (Mixed Tumor) is the most common salivary gland tumor, typically involving the parotid gland. The hallmark of this tumor is its cellular diversity, containing both epithelial and mesenchymal (myxoid, chondroid, or osteoid) components. **1. Why PLAG1 is the correct answer:** The molecular pathogenesis of pleomorphic adenoma frequently involves chromosomal rearrangements, most commonly a translocation involving **8q12**. This translocation leads to the overexpression of the **PLAG1 (Pleomorphic Adenoma Gene 1)** gene. PLAG1 is a zinc-finger transcription factor that, when upregulated, activates growth factor signaling pathways (like IGF-2), leading to uncontrolled cell proliferation and the characteristic mixed histological appearance of the tumor. **2. Why other options are incorrect:** * **PLAM1:** This is a distractor and does not correspond to a recognized gene involved in salivary gland neoplasia. * **PLAG2:** While PLAG2 belongs to the same gene family as PLAG1, it is not the primary driver for pleomorphic adenoma. PLAG1 remains the specific high-yield association for this tumor. **3. NEET-PG High-Yield Clinical Pearls:** * **Most common site:** Parotid gland (Superficial lobe). * **Clinical presentation:** A painless, slow-growing, mobile, firm mass [1]. * **Histology:** Characterized by "mixed" features—epithelial elements (ducts/acini) and mesenchymal-like stroma (often **chondromyxoid**). * **Risk of Malignancy:** Long-standing pleomorphic adenomas can transform into **Carcinoma ex pleomorphic adenoma**, which is highly aggressive [1]. * **Surgical Note:** They have a high recurrence rate if "enucleated" because of tiny finger-like projections (pseudopods) through the capsule; hence, **superficial parotidectomy** is the treatment of choice [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Head and Neck, pp. 751-753.
Question 438: A 65-year-old man complains of muscle weakness and a dry cough for 4 months. He has smoked two packs of cigarettes daily for 45 years. A chest X-ray shows a 4-cm central, left lung mass. Laboratory studies reveal hyperglycemia and hypertension. A transbronchial biopsy is diagnosed as small cell carcinoma. Metastases to the liver are detected by CT scan. Which of the following might account for the development of hyperglycemia and hypertension in this patient?
- A. Adrenal metastases
- B. Paraneoplastic syndrome (Correct Answer)
- C. Pituitary adenoma
- D. Pituitary metastases
Explanation: The patient presents with a classic triad: a heavy smoking history, a central lung mass (Small Cell Lung Carcinoma - SCLC), and signs of **Cushing Syndrome** (hyperglycemia and hypertension). [1] **1. Why Paraneoplastic Syndrome is correct:** Small cell lung carcinoma is a neuroendocrine tumor known for the ectopic production of hormones. In this case, the tumor cells are secreting **ACTH (Adrenocorticotropic hormone)**. Excess ACTH stimulates the adrenal cortex to produce high levels of cortisol, leading to secondary Cushing syndrome. [1] This manifests clinically as hypertension (due to mineralocorticoid effects) and hyperglycemia (due to increased gluconeogenesis and insulin resistance). **2. Why the other options are incorrect:** * **Adrenal metastases:** While SCLC frequently metastasizes to the adrenals, this usually results in adrenal destruction and **hypocortisolism** (Addisonian crisis), not hypercortisolism/hyperglycemia. [1] * **Pituitary adenoma:** While a pituitary adenoma can cause Cushing disease, it would be a primary event unrelated to the lung mass. The temporal association with a lung mass makes a paraneoplastic origin far more likely. * **Pituitary metastases:** Metastases to the pituitary are rare and typically cause **Diabetes Insipidus** (due to ADH deficiency) or panhypopituitarism, rather than hormone excess. **Clinical Pearls for NEET-PG:** * **SCLC Associations:** Remember the "3 S's": **S**mall cell, **S**moking, **S**entral location. * **Paraneoplastic Syndromes in SCLC:** 1. **ACTH:** Leads to Cushing Syndrome. 2. **SIADH:** Leads to hyponatremia. 3. **Lambert-Eaton Myasthenic Syndrome:** Muscle weakness due to antibodies against voltage-gated calcium channels. * **Squamous Cell Carcinoma (Lung):** Associated with **PTHrP** production leading to **Hypercalcemia**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 724-727.
Question 439: Paraneoplastic erythrocytosis is most commonly seen in which malignancy?
- A. Renal cell carcinoma (Correct Answer)
- B. Breast carcinoma
- C. Thyroid carcinoma
- D. Adrenal carcinoma
Explanation: **Explanation:** **1. Why Renal Cell Carcinoma (RCC) is correct:** Paraneoplastic erythrocytosis occurs due to the **ectopic production of Erythropoietin (EPO)** by tumor cells [1]. RCC is the most common malignancy associated with this phenomenon (occurring in approximately 1-5% of cases). The tumor cells autonomously secrete EPO, which stimulates the bone marrow to increase red blood cell production, leading to an elevated hematocrit [1]. **2. Analysis of Incorrect Options:** * **Breast Carcinoma:** Typically associated with paraneoplastic hypercalcemia (via PTHrP) or neurological syndromes, but not ectopic EPO production. * **Thyroid Carcinoma:** Medullary thyroid carcinoma is known for secreting Calcitonin or ACTH (Cushing syndrome), but erythrocytosis is not a feature. * **Adrenal Carcinoma:** Often presents with endocrine excesses like Cushing syndrome (ACTH) or Conn syndrome (Aldosterone), but does not typically produce EPO. **3. Clinical Pearls & High-Yield Facts for NEET-PG:** * **The "Big Four" of Ectopic EPO:** To remember the tumors causing paraneoplastic erythrocytosis, use the mnemonic **"Potentially Really High Hematocrit"**: 1. **P**heochromocytoma 2. **R**enal Cell Carcinoma (Most Common) 3. **H**epatocellular Carcinoma (HCC) 4. **H**emangioblastoma (specifically cerebellar) * **Uterine Leiomyomas:** Large fibroids are also a known non-malignant cause of ectopic EPO production. * **Distinction:** Unlike Polycythemia Vera, paraneoplastic erythrocytosis will show **elevated serum EPO levels** and an absence of the JAK2 mutation. * **Stauffer Syndrome:** Another unique paraneoplastic finding in RCC characterized by reversible hepatic dysfunction without liver metastases. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 492-493.
Question 440: Which type of sarcoma is commonly seen in infancy?
- A. Leiomyosarcoma
- B. Ewing's sarcoma
- C. Rhabdomyosarcoma (Correct Answer)
- D. Osteosarcoma
Explanation: **Explanation:** **Rhabdomyosarcoma (RMS)** is the most common soft tissue sarcoma of childhood and adolescence [2]. Specifically, the **Embryonal** subtype is frequently diagnosed in children under the age of 5, including infants [2]. These tumors arise from primitive mesenchymal cells programmed to form skeletal muscle. A classic clinical presentation in infants/young children is **Sarcoma Botryoides** (a variant of embryonal RMS), which appears as a "grape-like" mass protruding from the vagina or urinary bladder [1], [3]. **Analysis of Incorrect Options:** * **Leiomyosarcoma (A):** This is a malignant tumor of smooth muscle, most commonly seen in **adults** (middle-aged and elderly). It typically involves the uterus, retroperitoneum, or large blood vessels. * **Ewing’s Sarcoma (B):** While a common pediatric bone tumor, it typically peaks in the **second decade of life** (adolescents aged 10–20 years) [2]. It is rare in infancy. * **Osteosarcoma (D):** This is the most common primary malignant bone tumor, but it follows a bimodal distribution, peaking during the **adolescent growth spurt** (10–20 years) and in the elderly (secondary to Paget’s disease) [2]. **NEET-PG High-Yield Pearls:** * **Most common site for RMS:** Head and neck (orbit, nasopharynx), followed by the genitourinary tract. * **Histology:** Look for **Rhabdomyoblasts** (tadpole or strap cells) containing cross-striations. * **Immunohistochemistry (IHC):** Positive for **Desmin, Myogenin, and MyoD1** [3]. * **Genetic Association:** Alveolar RMS (a more aggressive subtype) is associated with **t(2;13)** or **t(1;13)** translocations involving the *PAX3/7* and *FOXO1* genes. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Female Genital Tract, pp. 1004-1005. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 483-484. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1224-1225.
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