Case presentation A 13-year-old boy presented with a right-sided flank mass, without associated symptoms. Physical examination revealed a painless, palpable mass in the right flank, approximately 6 × 5 cm in size. The mass was mobile over superficial tissues but appeared fixed to deeper planes.
The rest of the physical examination showed no abnormalities. Laboratory findings Normal white blood cell counts and C-reactive protein and hemoglobin levels Normal renal function parameters Normal hemostasis with a normal prothrombin time Non-contrast abdominal CT scan (Figure 1) Well-defined, round cystic lesion in the right retroperitoneal subhepatic region Smooth margins An internal detached membrane visible within the cyst Lesion measured 62.7 x 49.1 mm Figure 1 . CT scan showing a retroperitoneal cystic mass Surgery findings (Figure 2) Procedure performed in the left lateral decubitus…
