**Question:** Marker for seminoma testis is -

A. Alpha-fetoprotein (AFP)
B. Beta-human chorionic gonadotropin (β-hCG)
C. Lactate dehydrogenase (LDH)
D. Spermatozoa

**Core Concept:**
Seminoma is a type of germ cell tumor originating from the embryonic cells of the testes. These tumors produce specific markers that can be measured in the blood for diagnostic and monitoring purposes. In the case of seminoma, the primary markers are AFP (Alpha-fetoprotein) and β-hCG (Beta-human chorionic gonadotropin).

**Why the Correct Answer is Right:**
α-fetoprotein (AFP) and β-human chorionic gonadotropin (β-hCG) are both produced by various types of germ cell tumors, including seminoma. AFP is produced by yolk sac tumors, while β-hCG is produced by choriocarcinomas. In the context of seminoma, β-hCG is the more specific marker as it is produced by these tumors alone.

**Why Each Wrong Option is Incorrect:**
A. AFP is produced by yolk sac tumors, not seminoma. This makes it an incorrect marker for seminoma.
B. Although Lactate dehydrogenase (LDH) is elevated in various conditions, including seminoma, it is not specific to seminoma and does not distinguish seminoma from other germ cell tumors or other causes of elevated LDH levels.
C. Spermatozoa are mature male reproductive cells, and do not have any relevance to tumor markers or diagnosis.

**Clinical Pearl:**
β-hCG is a valuable marker for monitoring the response to treatment and evaluating the recurrence of seminoma. Its elevation signifies the presence of the tumor, and its normalization after treatment indicates a favorable prognosis. However, it is essential to differentiate between β-hCG and α-fetoprotein, as elevated α-fetoprotein levels are indicative of yolk sac tumors, not seminoma.

**Correct Answer:**
D. β-human chorionic gonadotropin (β-hCG) is the correct marker for seminoma. It is produced by choriocarcinomas, including seminoma, and is useful in monitoring the response to treatment and evaluating recurrence.

**Why Each Wrong Option is Incorrect:**
A. α-fetoprotein (AFP) is a marker for yolk sac tumors, not seminoma. Its elevation indicates the presence of yolk sac tumors, not seminoma.
B. Lactate dehydrogenase (LDH) is an enzyme involved in the citric acid cycle and is elevated in various conditions, including seminoma. However, it is not specific to seminoma and does not differentiate between different germ cell tumors or other causes of elevated LDH levels.
C. Spermatozoa are mature male reproductive cells and are not relevant to tumor markers or diagnosis.