Infected retroperitoneal cystic lymphangioma masquerading as psoas abscess.

A 2-year-old male is described who presented with fever, fixed flexion deformity of the right hip and a tender mass in the right iliac fossa. A clinical diagnosis of psoas abscess was made. Abdominal ultrasound was suggestive of an echogenic retroperitoneal cyst but could not accurately determine the nature of the cyst. A contrast CT scan showed a retroperitoneal cyst. At laparotomy, a large retroperitoneal cyst containing turbid fluid was found and was excised completely. Histopathological examination was suggestive of cystic lymphangioma. Clinical presentation of retroperitoneal lymphangioma may be variable and misleading, therefore complex imaging studies are necessary in the evaluation of this condition.