Neoplasia Practice Questions

Q: CD34 is a tumor marker used for which of the following?

Alveolar soft part sarcoma. **Explanation:** **CD34** is a transmembrane glycoprotein primarily expressed in hematopoietic stem cells and vascular endothelium [1]. In the context of soft tissue tumors, it is a highly sensitive marker for tumors with vascular differentiation or specific fibroblastic/mesenchymal origins [1]. **Why Alveolar Soft Part Sarcoma (ASPS) is correct:** While ASPS is classically characterized by the **TFE3** expression (due to the $t(X;17)$ translocation), it is highly vascularized with a prominent capillary network surrounding the nests of tumor cells (organoid pattern). CD34 is frequently used to highlight this characteristic **intratumoral vascularity**, which is a diagnostic hallmark of ASPS. **Analysis of Incorrect Options:** * **Ewing Sarcoma:** The gold standard marker is **CD99** (MIC2), showing a diffuse membranous staining pattern. It is typically negative for CD34. * **Myofibrosarcoma:** These tumors typically express **SMA** (Smooth Muscle Actin) and Desmin. CD34 is generally negative, helping to distinguish it from Solitary Fibrous Tumors (SFT). * **Inflammatory Myofibroblastic Tumor (IMT):** The characteristic marker is **ALK** (Anaplastic Lymphoma Kinase) rearrangement/expression (seen in ~50% of cases). **High-Yield Clinical Pearls for NEET-PG:** * **CD34 Positive Tumors (The "S" List):** **S**olitary Fibrous Tumor (Strong/Diffuse), **S**pindle cell lipoma, **S**ermatofibrosarcoma Protuberans (DFSP), and **S**angiosarcoma (Vascular tumors) [1]. * **ASPS Key Fact:** Look for "PAS-positive, diastase-resistant rhomboid crystals" in the cytoplasm. * **GIST:** CD34 is positive in ~70% of Gastrointestinal Stromal Tumors (though **DOG1** and **CD117** are more specific). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 523-528.

Q: The Ki 67 antigen is a marker associated with which carcinoma?

Breast. **Explanation:** **Ki-67** is a non-histone nuclear protein that serves as a potent **proliferation marker**. It is expressed during all active phases of the cell cycle (G1, S, G2, and mitosis) but is notably absent in the resting phase (G0). 1. **Why Breast Carcinoma is Correct:** In clinical practice, Ki-67 is most significantly utilized in the management of **Breast Carcinoma** [1]. It is a key component of the **molecular subtyping** of breast cancer (specifically distinguishing between Luminal A and Luminal B types). A high Ki-67 index (>20%) indicates a highly proliferative tumor, which correlates with a poorer prognosis but often a better response to chemotherapy. It is an essential IHC (Immunohistochemistry) marker used alongside ER, PR, and HER2/neu. 2. **Why Other Options are Incorrect:** * **Stomach and Lung Carcinomas:** While Ki-67 can be expressed in any rapidly dividing cancer cell (including gastric and lung cancers), it is not used as a standard diagnostic or prognostic "signature" marker for these organs in the same way it is standardized for breast cancer. For Lung cancer, markers like TTF-1 or p40 are more specific; for Stomach, HER2 or mismatch repair (MMR) proteins are more clinically relevant. **High-Yield Clinical Pearls for NEET-PG:** * **MIB-1:** This is the most commonly used monoclonal antibody to detect the Ki-67 antigen in paraffin-embedded sections. * **Prognostic vs. Predictive:** Ki-67 is a strong **prognostic** marker (predicts the natural course of the disease). * **Neuroendocrine Tumors (NETs):** Apart from breast cancer, Ki-67 is also the gold standard for **grading** Neuroendocrine tumors (e.g., Carcinoid tumors), where the "Ki-67 index" determines if a tumor is Grade 1, 2, or 3. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Breast, pp. 1059-1066.

Q: Which of the following is an example of a tumor suppressor gene?

RB. **Explanation:** The correct answer is **RB (Retinoblastoma gene)**. **1. Why RB is the Correct Answer:** The **RB gene**, located on chromosome **13q14** [1], is the "governor of the cell cycle" and the first tumor suppressor gene discovered [1]. It acts as a negative regulator of the cell cycle at the **G1/S checkpoint** [1]. In its hypophosphorylated (active) state, the RB protein binds to the **E2F transcription factor**, preventing the cell from entering the S-phase [1]. When mutated or inactivated, E2F is released, leading to uncontrolled cell proliferation [1]. It follows the "Knudson’s two-hit hypothesis" [1]. **2. Why Other Options are Incorrect:** * **A (myc):** This is a **proto-oncogene** that encodes a nuclear transcription factor [1]. It is associated with Burkitt Lymphoma (c-myc) and Neuroblastoma (n-myc). * **B (fos):** This is a **proto-oncogene** that belongs to the AP-1 transcription factor family, involved in cell proliferation and differentiation. * **C (ras):** This is the most common **proto-oncogene** mutated in human cancers [1]. It encodes a GTP-binding protein involved in signal transduction (MAP kinase pathway). **3. High-Yield Clinical Pearls for NEET-PG:** * **TP53:** Known as the "Guardian of the Genome," it is the most commonly mutated gene in human cancers [1]. * **Two-Hit Hypothesis:** Applies to tumor suppressor genes (like RB and APC), where both alleles must be inactivated for oncogenesis [1]. * **Associated Conditions:** RB mutations are linked to familial Retinoblastoma and an increased risk of **Osteosarcoma** later in life. * **Quiescence vs. Senescence:** RB-mediated arrest can lead to temporary (quiescence) or permanent (senescence) cell cycle exit. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 297-302.

Question 1

Which of the following can cause transitional cell carcinomas?

Accepted Answer

All of the above

Answer

Naphthylamine

Answer

Smoking

Answer

Bilharziasis

Question 2

Microscopic examination of a specimen shows 'Psammoma bodies'. What is the most characteristic association of Psammoma bodies?

Accepted Answer

Papillary carcinoma of the thyroid

Answer

Follicular carcinoma of the thyroid

Answer

Serous cystadenocarcinoma of the ovary

Answer

Meningioma

Question 3

CD34 is a tumor marker used for which of the following?

Accepted Answer

Alveolar soft part sarcoma

Answer

Ewing sarcoma

Answer

Myofibrosarcoma

Answer

Inflammatory myofibroblastic tumor

Question 4

Which of the following is not typically seen in the first decade of life?

Accepted Answer

Ameloblastoma

Answer

Retinoblastoma

Answer

Rhabdomyosarcoma

Answer

Neuroblastoma

Question 5

The Ki 67 antigen is a marker associated with which carcinoma?

Accepted Answer

Breast

Answer

Stomach

Answer

Lung

Answer

None of the above

Question 6

Which of the following is NOT a feature of a benign tumor?

Accepted Answer

Presence of local invasion

Answer

Absence of hyperchromasia of nucleus

Answer

Retained basal polarity

Answer

Slow growth

Question 7

Which of the following is an example of a tumor suppressor gene?

Accepted Answer

RB

Answer

myc

Answer

fos

Answer

ras

Question 8

Gleason score is used to grade which malignancy?

Accepted Answer

Prostate cancer

Answer

Transitional cell carcinoma

Answer

Penile cancer

Answer

Anal cancer

Question 9

Carcinoid tumors develop from which type of cells?

Accepted Answer

Kulchitsky cells

Answer

Hematopoietic cells

Answer

Neuroglial cells

Answer

Chromaffin cells

Question 10

Breslow thickness is used in the staging of which of the following conditions?

Accepted Answer

Melanoma

Answer

Squamous cell carcinoma

Answer

Basal cell carcinoma

Answer

Actinic keratosis

Neoplasia — MCQs

Neoplasia — MCQs

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