“…When rupture or secondary infection occurs, acute symptoms arise. The differential diagnosis of a cystic retroperitoneal mass includes abscess, chronic hematoma, necrotic malignant soft tissue tumor, cystic lymphangioma, pancreatic cyst, and hydronephrosis [ 4 , 11 ]. Diagnosis is established based on the combination of many parameters, including patient origin, clinical findings, imaging, and serology.…”