Giant true cyst of the spleen with elevated serum markers, carbohydrate antigen 19-9 and cancer antigen 125.

A 19-year-old woman presented with a left upper abdominal mass. Computed tomography of the abdomen showed a solitary cystic lesion in the splenic hilum, approximately 20×16 cm in size, demonstrating almost total displacement of the remaining splenic parenchyma. She had high serum concentrations of carbohydrate antigen 19-9 and cancer antigen 125. A splenectomy was performed. Immunohistochemical study confirmed the existence of an epithelial cyst. Following surgery, the serum concentrations of the tumour markers decreased gradually. True splenic cysts are rare and their origin is controversial. In splenic cysts with high serum concentrations of tumour markers, such as occurred in our patient, cystectomy or splenectomy were preferred to remove tumour marker-producing epithelium and to prevent recurrence after treatment. If the epithelial lining of the cyst cannot be detected under light microscopy, immunohistochemical study should be performed.