Some 2-5% of germ cell tumours are of extragonadal origin, with a retroperitoneal location being very rare. The majority of retroperitoneal germ cell tumours have metastasized from a testicular tumour. These tumours are diagnosed incidentally or symptomatically and nearly all present with high alpha-fetoprotein and lactate dehydrogenase levels. We describe the unusual case of a 31-year-old man with a yolk-sac, retroperitoneal germ cell tumour, with normal serum alpha-fetoprotein and lactate dehydrogenase levels, which has not previously been described. A testicular tumour was excluded by physical examination and additional tests. Our diagnosis was based on a high level of suspicion and histopathological results. As far as we know, this is the first case described with these characteristics.
Learning points: Extragonadal germ cell tumours are rare but can have fatal consequences if undiagnosed.The usual laboratory markers of the disease were absent in our patient.A high level of suspicion is required for diagnosis and close follow-up is required.
Keywords: Neoplasms; alpha-fetoproteins; extragonadal; germ cell and embryonal; male germ cell tumor; non-seminomatous; yolk-sac tumour.