[Intraabdominal mass with difficult diagnosis: Solitary fibrous tumor].

Solitary fibrous tumor (SFT) is a rare neoplasm of mesenchymal origin. The most commonly reported locations are the pleura and meninges. Less frequently, SFT manifests as an asymptomatic mass in the pancreas, liver, peritoneum or kidney. Clinical and radiological findings have failed to provide any specific diagnostic pattern but allow malignant development to be suspected due to infiltration or metastasis. In addition, preoperative cytology often yields inconclusive or misleading results. Therefore the definitive diagnosis is achieved after both surgical resection and immunohistochemical analysis, with markers such as CD34, vimentin and desmin. We present a case of SFT, which was difficult to diagnose, even after an extensive battery of tests based on imaging techniques.