Intratubular trophoblasts in the contralateral testis caused elevation of serum human chorionic gonadotropin following complete remission of stage II testicular tumor: a case report.

We report the case of a 22-year-old male who had a history of metastatic right testicular tumor successfully treated with chemotherapy and surgery. Twenty-one months after the initial treatment, the serum human chorionic gonadotropin started to increase gradually, but whole body imaging including the left testis revealed no abnormal finding except testicular microlithiasis. A biopsy of the left testis revealed intratubular germ cell neoplasia, unclassified type. After the human chorionic gonadotropin level reached 6.6 mIU/ml, he underwent left high orchiectomy. Histology demonstrated a small malignant germ cell tumor as well as intratubular germ cell neoplasia, unclassified type, both of which were negative for human chorionic gonadotropin staining. Besides these lesions, there were tiny foci of human chorionic gonadotropin-immunoreactive intratubular trophoblasts. Serum human chorionic gonadotropin normalized immediately after the orchiectomy, and he had no sign of recurrence at 6 months. The present case will provide new insight into the diagnosis of testicular tumor recurrence with isolated elevation of a serum tumor marker.