A unique case of bilateral testicular tumours: nonseminomatous germ cell tumour and contralateral spermatocytic tumour with 27 years apart.

Introduction Bilateral testicular tumours occur in 3-5% of all cases with testicular neoplasms. In the majority of cases, histology of the two new growths is identical. The time interval between the two neoplastic events rarely exceeds 10 years. Case presentation A 29 year-old man of Caucasian descent underwent right-sided orchiectomy for a nonseminomatous germ cell tumour. Postoperatively, he received adjuvant chemotherapy with 2 cycles of a cisplatin based regimen for clinical stage 1 disease. Twenty-seven years later when aged 56 years, he developed a lump in the left testis. Serum tumour markers including microRNA-371a-3p were within normal limits. Orchiectomy was performed. Histology revealed a spermatocytic tumour with positive stainings of SALL4, NUT, and CD117. No germ cell neoplasia in situ was detected in the tumour-surrounding tissue. Conclusion Histogenetically, testicular germ cell tumours are thought to derive from the precursor germ cell neoplasia in situ while spermatocytic tumours directly derive from adult spermatogonia. This case is exceptional, firstly because of the very long interval of 27 years between the two neoplastic events, and secondly, because of the unprecedented occurrence of two testicular neoplasms with different pathogenetic origins in one individual patient.