A 23-year-old woman was referred to our hospital because of microscopic hematuria. Ultrasonographic examination revealed a huge mass in the left upper abdomen, and she was admitted for further evaluation. Results of physical and laboratory examinations were normal. Levels of tumor markers (carcinoembryonic antigen, cancer antigen 19-9, DUPAN 2, elastase I) were all within the normal ranges. A computed tomographic scan revealed a low-density, monolocular cystic lesion measuring 9 × 8 cm between the tail of the pancreas and the hilus of the spleen (Figure 1). Magnetic resonance cholangiopancreatography demonstrated no connection between the tumor and the main pancreatic duct. After celiotomy, the tumor was resected with the adjacent organ. The resected specimen included a cystic lesion measuring 9 × 8.5 cm (Figure 2).