Objectives: To report the retroperitoneal histologic findings from a contemporary series of patients with pure seminoma at orchiectomy with an elevated serum α-fetoprotein (AFP) level. These patients underwent treatment on the assumption that the lesion was nonseminomatous germ cell tumor (NSGCT). Methods: We identified 22 patients from 1989 to 2009 with pure seminoma diagnosed at orchiectomy with an elevated serum AFP level (>15 ng/mL) either before or after orchiectomy. The retroperitoneal histologic and relapse data are reported. Results: The median preorchiectomy and prechemotherapy serum AFP level was 248 ng/mL (interquartile range 48-4693) and 279 ng/mL (interquartile range 66-5311), respectively. The percentage of patients with clinical Stage I, II, and III disease was 5%, 50%, and 45%, respectively. The percentage of patients with a good, intermediate, and poor risk status according to the International Germ Cell Cancer Collaborative Group was 32%, 32%, and 36%, respectively. Of the 22 patients, 21 underwent induction chemotherapy followed by retroperitoneal lymph node dissection. Overall, 67% of patients had NSGCT elements in the retroperitoneum. The histologic findings were pure teratoma in 38%, malignant transformation in 14%, and viable NSGCT in 14%. Also, 59% had some component of teratoma in the retroperitoneum. Only 1 patient (5%) had any seminoma in the retroperitoneum, but this patient also had retroperitoneal teratoma. Of the 22 patients, 7 developed a relapse and received salvage chemotherapy. The actuarial relapse-free survival rate at 5 and 10 years was 76% and 61%, respectively, reflecting the high percentage of patients with Stage II-III disease. Conclusions: Pure seminoma at orchiectomy with an elevated serum AFP level portends a high likelihood of NSGCT elements in the retroperitoneum.
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