Spontaneous regression of retroperitoneal metastases from a primary pure anaplastic seminoma: a case report.

Spontaneous regression of pure seminoma metastases is a rare phenomenon, with only a few cases reported to date. To the best of our knowledge, this is the first report of regression of anaplastic pure seminoma metastases located in the retroperitoneum. We present a 27-year-old man, a marihuana smoker, with metastatic pure anaplastic seminoma in the high retroperitoneal lymph nodes. After orchiectomy, his metastases regressed with no medication. Several mechanisms are suggested to explain this phenomenon, which still remains elusive.