Which gene mutation is commonly associated with malignant melanoma?
Tadpole cells, comma-shaped cells on histopathology are seen in -
Which of the following germ cell tumors is benign?
Ewing's sarcoma arises from which type of cells?
Perivascular lymphocytes & microglial nodules are seen in -
Bollinger bodies are seen in ?
Which of the following statements BEST characterizes the clinical significance of Barrett's esophagus?
Which of the following is the most common type of tongue cancer?
In which condition is pannus formation typically observed?
What is the most common cerebellar tumor in children?
NEET-PG 2012 - Pathology NEET-PG Practice Questions and MCQs
Question 51: Which gene mutation is commonly associated with malignant melanoma?
- A. MYCN
- B. CDKN2A (Correct Answer)
- C. RET
- D. BRAF
Explanation: ***CDK2A*** - CDK2A mutations are implicated in malignant melanoma as they disrupt the **cell cycle regulation**, contributing to uncontrolled cell growth [1]. - Loss of CDK2A function leads to reduced **p16INK4A**, a crucial inhibitor of cyclin-dependent kinases involved in **G1/S phase transition** [1,3]. - Germline mutations of p16 (CDKN2A) are present in 25% of melanoma-prone kindreds [2], and germline mutations in CDKN2A are associated with familial forms of melanoma [3]. *RET* - RET mutations are primarily associated with **medullary thyroid carcinoma** and **multiple endocrine neoplasia type 2**, not melanoma. - It is involved in the signaling pathways but does not have a direct link to melanoma pathogenesis. *None* - Suggesting "none" misrepresents the reality that specific mutations do occur in malignant melanoma, including **CDK2A** and **BRAF**. - This option fails to recognize the importance of genetic alterations in cancer development and progression. *N-myc* - N-myc mutations are primarily associated with **neuroblastoma** and not typically linked to malignant melanoma. - In melanoma, mutations of this gene do not play a significant role in its pathophysiology compared to another tumor suppressor gene like **CDK2A**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1150-1151. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 297-298. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 305-306.
Question 52: Tadpole cells, comma-shaped cells on histopathology are seen in -
- A. Trichoepithelioma
- B. Rhabdomyosarcoma (Correct Answer)
- C. Histiocytoma
- D. Leiomyosarcoma
Explanation: ***Rhabdomyosarcoma*** - **Tadpole cells** and **comma-shaped cells** are characteristic histological features of **rhabdomyosarcoma**, representing primitive mesenchymal cells differentiating towards skeletal muscle. - These cells are often pleomorphic, with eccentric nuclei and fibrillar eosinophilic cytoplasm, giving them their distinctive shapes. *Trichoepithelioma* - This is a benign adnexal tumor of follicular differentiation, characterized by nests of **basaloid cells**, **horn cysts**, and rudimentary hair structures. - It does not typically feature tadpole or comma-shaped cells. *Histiocytoma* - A **benign fibrous histiocytoma** (dermatofibroma) is composed of fibroblasts and histiocytes forming storiform patterns. - **Malignant fibrous histiocytoma** (now often reclassified as undifferentiated pleomorphic sarcoma) features pleomorphic spindle cells and giant cells, but not specifically tadpole or comma-shaped cells. *Leiomyosarcoma* - This is a malignant tumor of **smooth muscle origin**, characterized by spindle cells with blunt-ended nuclei, arranged in fascicles. - It lacks the tadpole or comma-shaped cells seen in rhabdomyosarcoma.
Question 53: Which of the following germ cell tumors is benign?
- A. Seminoma
- B. Dermoid cyst (Correct Answer)
- C. Embryonal carcinoma
- D. Yolk sac tumor
Explanation: ***Seminoma*** - Seminomas are well-known malignant **germ cell tumors**, primarily affecting young males [2]. - They are associated with elevated **human chorionic gonadotropin (hCG)** and can spread to lymph nodes [3]. *Leydig cell tumor* - These tumors are usually **benign** and arise from Leydig cells in the testes. - While they can produce **testosterone**, they do not typically exhibit malignancy. *Sertoli cell tumor* - Sertoli cell tumors are also generally **benign** and arise from Sertoli cells in the testes. - They lack the malignant behavior seen in seminomas and have a low rate of metastasis [1]. *Dermoid cyst* - Dermoid cysts are **benign** mature teratomas, commonly found in the ovaries or testicles. - They can contain different tissue types (like hair, fat, and teeth) but are not malignant. **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, pp. 979-980. [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.
Question 54: Ewing's sarcoma arises from which type of cells?
- A. G cells
- B. Totipotent cells
- C. Neurons
- D. Primitive neuroectodermal cells (Correct Answer)
Explanation: ***Primitive neuroectodermal cells*** - **Ewing's sarcoma** is a malignant small round blue cell tumor largely believed to arise from **primitive neuroectodermal cells**. - This cellular origin explains why it's often grouped under the term **PNET (Primitive Neuroectodermal Tumor)**. *G cells* - **G cells** are specialized **enteroendocrine cells** found in the stomach and duodenum that secrete **gastrin**. - They are involved in regulating gastric acid secretion and have no association with Ewing's sarcoma. *Totipotent cells* - **Totipotent cells** have the ability to differentiate into **any type of cell**, including embryonic and extraembryonic tissues. - While all cancers originate from cellular changes, Ewing's sarcoma originates from a more specific, committed cell lineage, not totipotent stem cells. *Neurons* - **Neurons** are the basic functional units of the nervous system, responsible for transmitting electrical and chemical signals. - While Ewing's sarcoma has neuroectodermal characteristics, it does not arise from fully differentiated neurons but rather from more **primitive precursors**.
Question 55: Perivascular lymphocytes & microglial nodules are seen in -
- A. HIV encephalitis (Correct Answer)
- B. CMV meningitis
- C. Bacterial meningitis
- D. Multiple sclerosis
Explanation: ***HIV encephalitis*** - **Perivascular lymphocytes** and **microglial nodules** are the characteristic histopathological hallmarks of **HIV encephalitis (HIV-associated dementia complex)** [1][2]. - Microglial nodules are formed by activated microglia and macrophages, often accompanied by **multinucleated giant cells** (the classic triad) [2]. - These features reflect chronic CNS inflammation and neuronal damage caused by HIV infection. *CMV meningitis* - Cytomegalovirus (CMV) infection in immunocompromised patients causes meningoencephalitis with characteristic **intranuclear ("owl's eye") inclusion bodies** and necrotizing inflammation. - The histological pattern differs from the microglial nodules and perivascular lymphocytes seen in HIV encephalitis. *Bacterial meningitis* - Characterized by prominent **neutrophilic infiltrate** in the subarachnoid space, fibrinopurulent exudate, and potential vasculitis. - Acute bacterial meningitis does not show the lymphocytic and microglial nodular pattern characteristic of viral encephalitis. *Multiple sclerosis* - An autoimmune demyelinating disease with **perivenular demyelinating plaques** containing lymphocytes and macrophages. - While perivascular inflammation occurs, **microglial nodules** are not a characteristic feature; instead, MS shows demyelination with reactive gliosis. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, p. 1278. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 711-712.
Question 56: Bollinger bodies are seen in ?
- A. Chickenpox
- B. Cowpox
- C. Fowlpox (Correct Answer)
- D. Smallpox
Explanation: **IMPORTANT NOTE:** In **human pathology**, the term "Bollinger bodies" classically refers to **sulfur granules** seen in **actinomycosis** (Actinomyces infection), which appear as basophilic masses with radiating eosinophilic clubs. However, this question uses the **veterinary pathology** definition, where Bollinger bodies refer to viral inclusions in avian diseases. ***Fowlpox*** - In **veterinary pathology**, **Bollinger bodies** are characteristic large, eosinophilic **intracytoplasmic inclusion bodies** found in cells infected with the **fowlpox virus** (avipoxvirus). - These inclusions are visible under light microscopy and are a diagnostic feature of **fowlpox**, a widespread avian disease. - Note: Fowlpox is **not a human disease** but affects birds. *Chickenpox* - Chickenpox, caused by the **varicella-zoster virus (VZV)**, is characterized by **intranuclear inclusion bodies** (Cowdry type A) [1]. - It does not form **Bollinger bodies**. *Cowpox* - Cowpox is caused by the **cowpox virus**, an **orthopoxvirus**, and produces **A-type cytoplasmic inclusion bodies** (A-type inclusions). - While these are cytoplasmic inclusions, they are not referred to as **Bollinger bodies**. *Smallpox* - Smallpox, caused by the **variola virus** (orthopoxvirus), is associated with **Guarnieri bodies**, which are **cytoplasmic inclusion bodies**. - These inclusions are distinct from **Bollinger bodies**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 366-367.
Question 57: Which of the following statements BEST characterizes the clinical significance of Barrett's esophagus?
- A. Barrett's esophagus is a precancerous condition (Correct Answer)
- B. Barrett's esophagus involves metaplasia of esophageal cells
- C. Intestinal type is the most common type
- D. It does not predispose to SCC but to adenocarcinoma
Explanation: ***Predisposes to SCC*** - Barrett's esophagus primarily predisposes individuals to **adenocarcinoma**, not squamous cell carcinoma (SCC) [2][3]. - SCC is associated with other conditions, such as **smoking** and **chronic irritation**, not Barrett's [3]. *Intestinal type is the most common type* - The intestinal type is indeed **common** in Barrett's esophagus, but it's not the only type present [2]. - Barrett's esophagus can also have a **gastric** type, but the intestinal type predominates in adenocarcinoma risk. *Metaplasia of cells* - This condition is defined by **intestinal metaplasia**, where squamous epithelium is replaced by columnar epithelium [2]. - Metaplasia is a **hallmark** of Barrett's esophagus and crucial for its diagnosis [2]. *Precancerous condition* - Barrett's esophagus is considered a **precancerous condition** because it increases the risk of transitioning to esophageal adenocarcinoma [1][2]. - The progression from Barrett's to cancer is well-documented in medical literature [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 764-765. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 348-349. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 766-767.
Question 58: Which of the following is the most common type of tongue cancer?
- A. Lymphoma
- B. Squamous cell carcinoma (Correct Answer)
- C. Adenocarcinoma
- D. Basal cell carcinoma
Explanation: ***Adenocarcinoma most common*** - The most common type of tongue cancer is **squamous cell carcinoma (SCC)**, not adenocarcinoma [1]. - Adenocarcinomas are less frequently associated with the tongue compared to SCC, which constitutes the majority of cases. *Tobacco is the cause* - Tobacco use is indeed a **significant risk factor** for various head and neck cancers, including tongue cancer [1]. - Smoking and smokeless tobacco are linked to increased incidence and severity of **squamous cell carcinoma** on the tongue [1]. *Deep cervical lymph nodes not involved* - Tongue cancers often metastasize to **deep cervical lymph nodes**, particularly in advanced stages. - Involvement of lymph nodes is a common feature that can affect prognosis and treatment strategies. *Lateral surface involved* - The **lateral surface** of the tongue is a common site for cancerous lesions, especially in cases related to tobacco use. - Tumors might also arise from other surfaces, but lateral involvement is characteristic of **squamous cell carcinoma**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 738-739.
Question 59: In which condition is pannus formation typically observed?
- A. RA (Correct Answer)
- B. Osteoarthritis (OA)
- C. Gout (Gouty Arthritis)
- D. Psoriatic Arthritis (PsA)
Explanation: ***RA*** - **Pannus** is a characteristic feature of **rheumatoid arthritis**, representing an aggressive, hyperplastic synovial tissue that invades and destroys cartilage and bone [1], [2]. - This destructive granulation tissue primarily consists of fibroblasts, macrophages, and inflammatory cells, contributing to joint erosion [1]. *Osteoarthritis (OA)* - While **osteophytes** (bone spurs) and **cartilage degradation** are hallmarks of OA, **pannus formation** is not seen. - OA involves breakdown of articular cartilage due to mechanical stress and biochemical changes, not synovial invasion. *Gout (Gouty Arthritis)* - Gout is characterized by the deposition of **monosodium urate crystals** in joints, leading to acute inflammation [4]. - The formation of **tophi** (urate crystal deposits) is typical, but not **pannus** [4]. *Psoriatic Arthritis (PsA)* - PsA can cause joint inflammation and erosion similar to RA but does not typically involve the extensive **pannus formation** characteristic of RA [3]. - Specific features of PsA include **enthesitis**, dactylitis and involvement of **DIP joints** [3]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 677-678. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1212. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1214-1215. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1218.
Question 60: What is the most common cerebellar tumor in children?
- A. Ependymoma
- B. Medulloblastoma (Correct Answer)
- C. PNET
- D. Astrocytoma
Explanation: ***Medulloblastoma*** - **Medulloblastoma** is the most common **malignant** cerebellar tumor in children, accounting for about 20% of all childhood brain tumors [2]. - In the context of this question, medulloblastoma is considered the "most common cerebellar tumor" as it is the most frequently encountered **malignant** tumor requiring aggressive treatment. - These tumors arise from neuroectodermal cells in the cerebellum and are typically **highly aggressive**, often spreading through the cerebrospinal fluid (CSF) pathways [1], [2]. - Peak incidence is between 5-9 years of age, with a male predominance [1]. *Astrocytoma* - **Cerebellar pilocytic astrocytomas** are actually the most common **benign** cerebellar tumor in children and represent a significant portion of all cerebellar tumors [1]. - However, in competitive exam contexts, when asking about "most common cerebellar tumor," the question typically refers to **malignant tumors**, where medulloblastoma takes precedence. - **Pilocytic astrocytomas** are usually low-grade (WHO Grade I) and have an excellent prognosis, often presenting as cystic lesions with a mural nodule. *Ependymoma* - **Ependymomas** are the third most common posterior fossa tumor in children (after medulloblastoma and pilocytic astrocytoma). - They typically arise from the ependymal lining of the **fourth ventricle**, making them cerebellar-adjacent rather than primarily cerebellar tumors [3], [4]. - They account for about 10% of pediatric brain tumors and have an intermediate prognosis. *PNET* - **PNET (Primitive Neuroectodermal Tumor)** is a historical term that has largely been replaced by more specific classifications in the current WHO CNS tumor classification. - Medulloblastoma was previously classified as a type of PNET, but is now recognized as a distinct entity. - The term PNET is now rarely used in modern neuropathology practice, having been superseded by molecular and genetic classification systems. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 725-726. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1314-1315. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 726-727. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1312-1313.