Neoplasia Practice Questions

Q: Which of the following is the best example of a proto-oncogene activated by point mutation?

Ras. **Explanation:** **Correct Answer: A. Ras** The **Ras gene family** (H-ras, K-ras, N-ras) is the most common example of a proto-oncogene activated by **point mutations**. In its normal state, Ras flips between an active (GTP-bound) and inactive (GDP-bound) state. A single point mutation (most commonly at codons 12, 13, or 61) interferes with GTP hydrolysis, trapping Ras in a permanent "on" position. This leads to continuous mitogenic signaling to the nucleus. **Why the other options are incorrect:** * **B & C. N-myc and L-myc:** These members of the *myc* family are typically activated by **gene amplification** (increased copy number), not point mutations [1]. *N-myc* amplification is a classic prognostic marker in Neuroblastoma, while *L-myc* is associated with Small Cell Carcinoma of the lung. * **D. Abl:** The *c-Abl* proto-oncogene is activated by **balanced translocation**, specifically t(9;22), which forms the BCR-ABL fusion protein (Philadelphia chromosome) characteristic of Chronic Myeloid Leukemia (CML) [1], [2]. **High-Yield Clinical Pearls for NEET-PG:** * **K-ras mutations** are highly associated with **Pancreatic adenocarcinoma** (90%) and Colon cancer. * **H-ras mutations** are linked to Bladder tumors. * **N-ras mutations** are frequently seen in Melanomas and Hematologic malignancies. * **Mechanism Summary:** Ras activation = Point mutation; Myc activation = Amplification/Translocation; Abl activation = Translocation. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 292. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 295-296.

Q: The level of alpha fetoprotein is raised in all of the following conditions except?

Dysgerminoma. **Explanation:** Alpha-fetoprotein (AFP) is a glycoprotein synthesized primarily by the fetal liver and yolk sac. In adults, elevated levels serve as a crucial tumor marker or an indicator of specific regenerative/inflammatory liver processes. **Why Dysgerminoma is the correct answer:** Dysgerminoma is the female counterpart of the male seminoma. It is a germ cell tumor characterized by the proliferation of primitive germ cells that have not differentiated into yolk sac or embryonal structures. Consequently, it **does not produce AFP**. The characteristic markers for Dysgerminoma are **LDH** (Lactate Dehydrogenase) and occasionally **hCG** (if syncytiotrophoblastic giant cells are present). **Analysis of Incorrect Options:** * **Cirrhosis of the liver:** AFP can be mildly to moderately elevated in non-malignant chronic liver diseases like cirrhosis and hepatitis due to active hepatocyte regeneration. * **Hepatocellular carcinoma (HCC):** AFP is the classic tumor marker for HCC. Levels >400–500 ng/mL in a high-risk patient are highly suggestive of this malignancy. * **Yolk sac tumor (Endodermal Sinus Tumor):** This tumor histologically mimics the fetal yolk sac; therefore, it produces **extremely high levels of AFP**. It is the most common testicular tumor in children under 3 years. **NEET-PG High-Yield Pearls:** 1. **AFP in Pregnancy:** Raised in Neural Tube Defects (NTDs) and abdominal wall defects (omphalocele/gastroschisis); **Decreased** in Down Syndrome (Trisomy 21). 2. **Schiller-Duval Bodies:** Pathognomonic histological finding in Yolk Sac Tumors. 3. **Mixed Germ Cell Tumors:** If a patient has a "Dysgerminoma" but the AFP is elevated, it indicates a mixed component (likely Yolk Sac). 4. **Rule of Thumb:** AFP = Liver (HCC/Cirrhosis) or Yolk Sac derivatives.

Question 1

Which of the following statements about p53 is FALSE?

Accepted Answer

Non-mutated wild-type p53 is associated with neoplasia in childhood.

Answer

It is present on chromosome 17.

Answer

It causes cell cycle arrest in G1.

Answer

It has a molecular weight of 53 KDa.

Question 2

Infantile polycythemia is seen in which of the following conditions?

Accepted Answer

Cerebellar hemangioma

Answer

Retinoblastoma

Answer

Hepatoblastoma

Answer

All of the above

Question 3

Which of the following sites are predisposed to carcinoma due to smoking?

Accepted Answer

Bladder, Buccal mucosa, Stomach

Answer

Bladder, Buccal mucosa, Breast

Answer

Bladder, Ovary, Breast

Answer

Ovary, Buccal mucosa, Stomach

Question 4

All are malignant tumors, except:

Accepted Answer

Fibromatosis

Answer

Chloroma

Answer

Askin's tumor

Answer

Liposarcoma

Question 5

Which of the following is the best example of a proto-oncogene activated by point mutation?

Accepted Answer

Ras

Answer

N-myc

Answer

L-myc

Answer

Abl

Question 6

The level of alpha fetoprotein is raised in all of the following conditions except?

Accepted Answer

Dysgerminoma

Answer

Cirrhosis of the liver

Answer

Hepatocellular carcinoma

Answer

Yolk sac tumor

Question 7

Alpha-fetoprotein (AFP) levels are increased in all of the following conditions except?

Accepted Answer

Seminoma

Answer

Pregnancy

Answer

Hepatocellular carcinoma (HCC)

Answer

Lung carcinoma

Question 8

Which of the following is a marker of carcinoma?

Accepted Answer

Cytokeratin

Answer

Vimentin

Answer

Calretinin

Answer

CD45

Question 9

Smoking causes all of the following cancers except:

Accepted Answer

Endometrial carcinoma

Answer

Oral cancer

Answer

Kidney cancer

Answer

Bladder cancer

Question 10

Which of the following types of cancers is Human Papilloma Virus (HPV) most commonly associated with?

Accepted Answer

Anogenital

Answer

Prostate

Answer

Oral

Answer

Lung

Neoplasia — MCQs

Neoplasia — MCQs

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