Abstract
A rare case of a pure yolk sac testicular tumour presenting in an adult with learning difficulties is presented. Pure yolk sac tumours are much more common in children, but when they do occur in adults, onset can be both insidious and aggressive. The best practice for identification involves the precise use of ultrasound, blood tests for tumour markers and FDG-PET/CT imaging for staging. Dual-phase treatment in the form of radical inguinal orchidectomy performed expediently followed by chemotherapy is the mainstay of treatment in advanced cases.