A 37-year-old man, with no personal or urological history of interest, who came to our surgery referred from the emergency department for pain and swelling of the left testicle.

He referred a picture of progressive left testicular swelling of two months' evolution. He reported no fever, no accompanying urological symptoms, and no general malaise.

On palpation, the left testicle was indurated and slightly painful, with a normal epididymis. The right testicle was normal in size and consistency.

Testicular ultrasound showed a large nodular lesion in the left testicle, with a mixed pattern of cystic areas and areas with fine echogenic content, and solid nodular lesions in the right testicle, findings related to bilateral testicular neoplasia.

Tumour markers showed elevated α-FTP (48.4 ng/mL), normal β-HCG (<0.6 mIU/mL) and normal LDH.

No pathological findings of interest were found in the thoraco-abdominal-pelvic CT scan.

The patient was referred to the fertility department for seminal cryopreservation. Subsequently, a left inguinal orchiectomy was performed with high cord ligation, and a right testicular biopsy via the inguinal route, after clamping the spermatic cord, which was reported intraoperatively as positive for malignant germ cells, so the surgery was completed with a right inguinal orchiectomy.

The anatomopathological study was reported as follows: Left testicle: tumour 5 cm in diameter with cystic areas, corresponding to a mixed germinal tumour formed in similar proportions by adult embryonal carcinoma and teratoma with both mature and immature elements, which does not exceed the albuginea.

Right testicle: greyish tumour 2.5 cm in diameter, corresponding to seminoma of the classic variety, with images of intratubular neoplasia, without involvement of the albuginea, epididymis or spermatic cord.

Adjuvant chemotherapy treatment was administered with the modified BEP scheme (x2 cycles), subsequently presenting negative markers: α-FTP (3.7 ng/mL), β-HCG (<0.6 mIU/mL) and normal LDH.

Currently, 10 months after the initial diagnosis of stage I bilateral testicular tumour, the patient is asymptomatic, with negative tumour markers, normal radiological studies and on hormone replacement therapy with periodic controls of testosterone levels.