Intrascrotal epidermoid cyst with extension into the pelvis.

An 8-year-old boy presented with an asymptomatic extratesticular, scrotal epidermoid cyst with extension across the urogenital diaphragm into the pelvis. While routine contrast studies and ultrasound were performed, magnetic resonance imaging was most useful in depicting the anatomical boundaries of the lesion, including the intrapelvic extension. Complete excision was performed transcrotally. The lesion is histologically indistinguishable from epidermoid cysts found elsewhere in the external genitalia, that is the penis, scrotum or testis. The etiology is unknown but it may represent a monolayer teratoma of germ cell origin or abnormal embryological closure of the median raphe.