Neoplasia Practice Questions

Q: Which gene is involved in Gastrointestinal Stromal Tumors (GIST)?

C-KIT. **Explanation:** **1. Why C-KIT is Correct:** Gastrointestinal Stromal Tumors (GIST) are the most common mesenchymal tumors of the GI tract, arising from the **Interstitial Cells of Cajal (ICC)**—the "pacemakers" of the gut. Approximately **85-90%** of GISTs are driven by gain-of-function mutations in the **c-KIT (CD117)** proto-oncogene [1], which encodes a receptor tyrosine kinase. This mutation leads to constitutive activation of the kinase, promoting uncontrolled cell proliferation [1]. A smaller subset (approx. 5-10%) involves mutations in the **PDGFRA** gene [1]. **2. Why Other Options are Incorrect:** * **BRCA-1 & BRCA-2:** These are tumor suppressor genes involved in DNA repair (homologous recombination). Mutations are primarily associated with hereditary **Breast and Ovarian Cancer** syndromes, not mesenchymal GI tumors. * **p53:** Known as the "Guardian of the Genome," this is the most commonly mutated tumor suppressor gene in human cancers (e.g., Li-Fraumeni syndrome). While it may be involved in the progression of many tumors, it is not the primary diagnostic driver for GIST. **3. High-Yield Clinical Pearls for NEET-PG:** * **Diagnostic Marker:** **CD117** is the most sensitive and specific immunohistochemical (IHC) marker for GIST. **DOG1** (Discovered on GIST-1) is another highly specific marker. * **Morphology:** GISTs can show **Spindle cell** (most common) or **Epithelioid** patterns. * **Targeted Therapy:** The discovery of c-KIT mutations revolutionized treatment. **Imatinib mesylate** (a tyrosine kinase inhibitor) is the first-line targeted therapy for unresectable or metastatic GIST. * **Location:** The **Stomach** (60%) is the most common site, followed by the small intestine [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 782-783.

Question 1

Which of the following statements is false regarding tumor hypoxia?

Accepted Answer

Oxygen does not affect the radiosensitivity of tumors.

Answer

Hypoxia in tumors can result from two different mechanisms: chronic hypoxia and acute hypoxia.

Answer

Acute hypoxia is caused by a temporary closing of a blood vessel in the tumor.

Answer

Chronic hypoxia is caused by the limited diffusion distance of oxygen through tissue that is respiring.

Question 2

Teratoma is best described as:

Accepted Answer

A hamartous developmental manifestation consisting of three different germ layers

Answer

Occurs most commonly in the ovary and testis

Answer

Originates from pluripotent cells capable of differentiating into all three germ layers

Answer

Often associated with increased levels of alpha-fetoprotein (AFP)

Question 3

The BCR-ABL hybrid gene is characteristically present in which of the following conditions?

Accepted Answer

Chronic myeloid leukemia (CML)

Answer

Burkitt's lymphoma

Answer

Retinoblastoma

Answer

Breast carcinoma

Question 4

What is the most important prognostic factor for breast carcinoma?

Accepted Answer

Lymph node involvement

Answer

Age of the patient

Answer

Genetic factors

Answer

Family history

Question 5

A 60-year-old male presents with hematuria and weight loss. Cystoscopy biopsy of a superficial lesion in the bladder shows hyperchromatic nuclei, an increased nuclear-to-cytoplasmic ratio. The lesion involves the full thickness of the epithelium but does not invade the basement membrane. What is the diagnosis?

Accepted Answer

Bladder carcinoma in situ

Answer

Dysplasia

Answer

Metaplasia

Answer

Micro invasion

Question 6

What of the following is essential for tumor metastasis?

Accepted Answer

Angiogenesis

Answer

Tumorogenesis

Answer

Apoptosis

Answer

Inhibition of tyrosine kinase activity

Question 7

Squamous papilloma is induced by?

Accepted Answer

HPV

Answer

EBV

Answer

HSV

Answer

CMV

Question 8

The most common histologic type of carcinoma of the oral cavity is?

Accepted Answer

Squamous cell carcinoma

Answer

Adenocarcinoma

Answer

Clear cell carcinoma

Answer

Large cell undifferentiated carcinoma

Question 9

Which gene is involved in Gastrointestinal Stromal Tumors (GIST)?

Accepted Answer

C-KIT

Answer

BRAC-1

Answer

p53

Answer

BRAC-2

Question 10

Malignant neoplasms show all the following features EXCEPT?

Accepted Answer

Encapsulation

Answer

Disorganized cell structure

Answer

Invasion of blood vessels

Answer

Rapid, erratic growth

Neoplasia — MCQs

Neoplasia — MCQs

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