Devil within: an incidental and rare finding of an extragonandal retroperitoneal germ cell teratoma carcinoid tumour.

Extragonadal germ cell tumours (GCTs) are uncommon neoplasms comprising approximately 2%-5% of all GCTs. Of these, approximately 30%-40% occurs as primary retroperitoneal GCTs. This case report details the presentation, diagnosis and management of a 53-year-old man presenting with an incidental finding of a primary extragonadal retroperitoneal teratoma with carcinoid transformation.