Synchronous bilateral testicular cancer with discordant histopathology occurring in a 20-year-old patient: A case report and review of the literature.

Bilateral testicular tumors are very rare, accounting for 1%-5% of all testicular germ-cell tumors (TGCTs). The vast majority of primary bilateral TGCTs are metachronous, with synchronous tumors comprising approximately 0.5%-1% of all cases. Those occurring synchronously share mostly the same histological pattern, predominantly seminoma, with synchronous bilateral TGCTs (SBTGCTs) with discordant subtypes being extremely rare. We present the case of a 20-year-old male complaining of a palpable painless right testicular mass incidentally noticed during sexual intercourse. Ultrasonography (US) and magnetic resonance imaging (MRI) of the scrotum demonstrated bilateral testicular lesions, while staging with contrast-enhanced computed tomography (CT) exhibited normal findings. Right radical orchiectomy and left testis-sparing surgery (TSS) with concomitant onco-testicular sperm extraction (onco-TESE) were initially performed. Histology of the right testis revealed a mixed germ-cell tumor, consisting of seminoma and embryonal carcinoma, while that from the left testis disclosed embryonal carcinoma and intratubular germ-cell neoplasia unclassified (IGCNU) infiltrating the surgical margins. Hence, left orchiectomy was subsequently scheduled with histology unveiling IGCNU in the greatest part of the remaining testicular parenchyma. Following adjuvant chemotherapy, with bleomycin, etoposide, and cisplatin (BEP), the patient received testosterone replacement therapy and remained free of recurrence at an 18-month follow-up. This case highlights both the rarity of a bilateral testicular tumor's synchronous appearance and its extremely infrequent discordant histopathology. A comprehensive review of the major series of SBTGCTs with discordant histology cited in the literature is additionally presented.