RESUMEN
Retroperitoneal cysts (RPCs) are rare types of cyst in the retroperitoneal space that are frequently misdiagnosed as gynecological tumors. This case report details, an epidermoid RPC, identified through 2D ultrasound, with attempts to visualize its rendered images using 3D ultrasound. A 39-year-old female patient was admitted to the hospital following the detection of a pelvic mass during a routine physical examination. Initially, the lesion was suspected to be an ovarian tumor, but subsequent ultrasound investigations suggested an epidermoid RPC. This diagnosis was later confirmed by pelvic magnetic resonance imaging. The definitive diagnosis was made following laparoscopic exploration and pathological examination. This case is shared to analyze the ultrasound characteristics of epidermoid RPCs.