[Large retroperitoneal mass in a young patient].

This medical case report describes the diagnosis and treatment of a 24-year-old man with a germ cell tumor. The patient presented to the emergency practice with a palpable mass in the left upper abdomen that had been present for three weeks, without any additional symptoms. Bedside ultrasonography revealed an inhomogeneous tumor in the retroperitoneum. Further ultrasound examination of the abdomen and testicle identified a possible primary tumor in the left testicle, which was classified as a tumor with non-seminoma parts based on laboratory findings with markedly elevated Beta-HCG and AFP levels. Additionally a primary orchidectomy followed for definitive diagnosis. The patient underwent chemotherapy with four cycles of cisplatin, etoposide, and bleomycin, which was well-tolerated. After the removal of the remaining retroperitoneal mass, complete remission was achieved. This case highlights the importance of comprehensive diagnostics and interdisciplinary collaboration in the treatment of germ cell tumors, as well as the critical role of ultrasound in both emergency and primary care settings. With early diagnosis and appropriate therapy, patients with these tumors have a very high survival rate despite the metastasis. Keywords: Germ cell tumour, retroperitoneal mass, beta-HCG and AFP, orchiectomy, chemotherapy.