Non-seminomatous germ cell tumors of the testis: morphology of retroperitoneal lymph node metastases after chemotherapy.

Gross and histological examination of residual retroperitoneal mature teratoma revealed different findings in patients treated with PVB remission-induction chemotherapy with maintenance chemotherapy followed by an RLND 4-6 months after PVB chemotherapy (group I) as compared to patients who received PVB chemotherapy only and underwent an RLND after 4-6 weeks (group II). RLND specimens in group I predominantly contained mature teratoma with organoid differentiation, whereas the specimens in group II often consisted of small mature teratoma areas with less-differentiated structures next to large areas of fresh tumor necrosis. Our findings suggest that, either due to maintenance chemotherapy or due to a prolonged time interval between PVB remission-induction chemotherapy and RLND, mature teratoma grows and differentiates further from tissue level to organoid level.