An Unusual Case of Primary Retroperitoneal Germ Cell Tumour in a Young Man

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.