Giant Solitary Fibrous Tumor of Pleura Presenting Both Benign and Malignant Features

Objective: Rare disease Background: The incidence of solitary fibrous tumor of the pleura (SFTP) is less than 5% of all pleural tumors. It is important to determine whether the tumor is benign or malignant in deciding on treatment and estimating prognosis, but this can sometimes be difficult. Case Report: A 59-year-old woman with no prior medical history presented with a 4-month history of right back pain and dyspnea. Contrast-enhanced computed tomography revealed a giant oval mass with inhomogeneous intensities, and bloody pleural effusion in the right thoracic cavity, proved to be solitary fibrous tumor of pleura (SFTP) under the complete thoracoscopic resection. The resected tumor seemed to have several malignant features, including large size of tumor, inhomogeneous intensities, and pleural effusion due to intratumor hemorrhage; however, Ki-67 (MIB-I) proliferation index was less than 1%, with no recurrence seen within 2 year after symptom onset. Conclusions: We managed a case of SFTP presenting both malignant and benign features. In patients with SFTP, multi-disciplinary discussion among the clinician, radiologist, and pathologist was considered to be needed for estimating disease prognosis.