Laparoscopic Excision of a Psoas Epidermoid Cyst: A Report of a Rare Case.

Retroperitoneal cysts are rare, and retroperitoneal epidermoid cysts are fewer in number; these cysts often pose challenges in being diagnostically vague. This report presents a case of a 41-year-old man who presented with dysuria and bilateral loin pain, and was treated for bilateral ureteric calculi shown on an abdominal X-ray. The patient re-presented with pain, and further imaging revealed a provisional diagnosis of a hydatid cyst, demonstrated by a large mass within the right psoas muscle. Histopathology after a complete laparoscopic excision confirmed a benign epidermoid cyst (Gonzalez-Crussi grade 0). This case demonstrates that retroperitoneal cysts pose a diagnostic challenge due to vague symptoms and multiple plausible differential diagnoses. A multimodal evaluation and complete surgical excision have proven to be therapeutically vital, with a minimal rate of recurrence.