**Question:** Pleomorphism may be present in: September 2004

**Core Concept:** Pleomorphism is a characteristic feature of certain types of tumors, especially sarcomas, where cells exhibit diverse morphologies within the same tumor. This phenomenon is usually a sign of malignancy.

**Why the Correct Answer is Right:** Pleomorphism occurs due to genetic mutations that cause abnormal cell growth and differentiation. In sarcomas, genetic alterations in tumor suppressor genes (e.g., p53) and proto-oncogenes (e.g., ras) can lead to uncontrolled cell division and diverse cell morphologies. Pleomorphism is a hallmark of sarcomas as it reflects the heterogeneity of the tumor and indicates a higher risk of recurrence and poor prognosis.

**Why Each Wrong Option is Incorrect:**

A. **Absence of pleomorphism**: This is not correct because, as mentioned earlier, pleomorphism is a feature of sarcomas and other types of tumors. Absence of pleomorphism may indicate a different type of tumor or a benign condition.

B. **Presence of pleomorphism in normal cells**: Pleomorphism is a pathological feature found in tumors, not healthy cells. In normal cells, uniformity in size and shape is expected due to the normal functioning of cell cycle control mechanisms.

C. **Pleomorphism in lymphocytes**: While lymphocytes can exhibit some degree of morphological variation, the degree of pleomorphism seen in sarcomas is significantly higher and more diverse. Lymphomas, for example, usually display a more homogeneous cell population compared to sarcomas.

D. **Pleomorphism in benign tumors**: Pleomorphism is not limited to malignant tumors; it can also be observed in some benign tumors, such as ganglioneuroma or ganglioneuroblastoma. However, the degree and extent of pleomorphism is generally milder and less diverse than that seen in sarcomas.

**Clinical Pearl:** Pleomorphism should prompt the suspicion of a malignant tumor, specifically sarcoma, and should prompt the clinician to order further diagnostic tests and workup to confirm the diagnosis. Awareness of pleomorphism in various conditions helps in narrowing down the differential diagnosis and guides appropriate further investigations.

**Correct Answer:** D. Pleomorphism in benign tumors

**Explanation:** Pleomorphism can be seen in some benign tumors, such as ganglioneuroma or ganglioneuroblastoma. While the degree and extent of pleomorphism in benign tumors is generally milder and less diverse than that seen in sarcomas, it can still be present. This helps to differentiate between benign and malignant tumors and guides the clinician to further diagnostic tests and workup to confirm the diagnosis.