**Core Concept:**
Embryonal carcinoma is a rare malignant germ cell tumor that can present in the testis. In this case, the patient underwent a retroperitoneal lymph node dissection at age 15 for embryonal carcinoma of right testis, which may have led to testicular dysfunction. Semen analysis shows reduced sperm count and absence of fructose, indicating impaired testicular function. Biopsy of the testis reveals normal spermatogenesis, which suggests that the patient's fertility issue is not due to a primary testicular pathology.

**Why the Correct Answer is Right:**
In this scenario, the patient presents with infertility despite having undergone surgery for a malignant germ cell tumor in the testis. The biopsy demonstrates normal spermatogenesis, suggesting that the patient's fertility issue is not due to primary testicular pathology. This indicates that the patient's infertility is likely secondary to the surgical intervention itself, specifically the retroperitoneal lymph node dissection.

**Why Each Wrong Option is Incorrect:**
A. This option is incorrect because the biopsy shows normal spermatogenesis, ruling out primary testicular pathology as the cause of infertility.
B. This option is incorrect as the patient's sperm count and fructose absence on semen analysis suggest impaired testicular function due to the surgery.
C. Although the patient's sperm count may be low, the absence of fructose on semen analysis is more concerning as it indicates a blockage in the epididymis or vas deferens, which could be caused by the retroperitoneal lymph node dissection. However, the biopsy shows normal spermatogenesis, suggesting that the surgery did not cause primary testicular pathology.
D. This option is incorrect because the biopsy shows normal spermatogenesis, ruling out primary testicular pathology as the cause of infertility.

**Clinical Pearl:**
This case highlights the importance of considering both primary and secondary causes of male infertility. Although the patient has undergone surgery for a malignant germ cell tumor, the presence of normal spermatogenesis on biopsy indicates that the surgery itself may have caused impairment in testicular function leading to infertility. Semen analysis can help identify specific abnormalities such as absence of fructose, which may indicate epididymal or vas deferens obstruction due to the surgical intervention.