Concurrent development of testicular seminoma and choriocarcinoma of the superior mediastinum, presented as cervical mass: a case report and implications about pathogenesis of germ-cell tumours

BACKGROUND: Synchronous presentation of more than one germ cell tumours of different histology in the same patient is considered to be very rare. In these cases of multiple germ cell tumours, strong theoretical and clinical data suggest an underlying common pathogenetic mechanism concerning genetic instability or abnormalities during the pluripotent embryonic differentiation and maturation of the germ cell. CASE PRESENTATION: A 25 year-old young man presented with an enlarging, slightly painful left cervical mass. Despite the initial disorientation of the diagnosis to a possible thyroid disorder, the patient underwent complete surgical resection of the mass revealing mediastinal choriocarcinoma. Subsequent ultrasound of the scrotum indicated the presence of a small lobular node in the upper pole of the left testicle and the patient underwent radical left inguinal orchiectomy disclosing a typical seminoma. Based on these results, the patient received 4 cycles of Bleomycin, Etoposide and Platinum chemotherapy experiencing only mild toxicity and resulting in complete ongoing clinical and biochemical remission. CONCLUSION: The pathogenesis of concurrent germ cell tumours in the same patient remains an area of controversy. Although the genetic instability of the pluripotent germ cell offers an adequate explanation, the possibility of metastasis from the primary, less differentiated tumour to a distant location as a more mature subtype cannot be excluded. Possible development of a metastatic site of different histology and thus biological behaviour (e.g choriocarcinoma) should be anticipated. Furthermore, urologists, pathologists and medical oncologists should be meticulous in the original pathological diagnosis in these patients, since there is a significant frequency of germ cell tumours with mixed or overlapping histological elements with diverse potential of evolution and differentiation