Recurrent solitary fibrous tumor of the pleura with malignant transformation: a case report.

We report a rare case of recurrent solitary fibrous tumor (SFT) of the pleura with suspicious malignant transformation. A 78-year-old man had undergone prior surgical resection of the primary and recurrent SFT tumors at 11 and 2 years before the current presentation. Although his primary tumor had a round shape and did not show invasive growth, the current recurrent tumor extended through the neural foramen and had an osteoclastic progression into the thoracic spine. A computed tomography (CT) guided needle biopsy was performed and the pathological diagnosis of the tumor was confirmed as the recurrence of SFT. Immunohistochemically, the MIB-1 proliferation index (Ki-67) of the primary tumor and the current tumor was 1.74 and 30.00%, respectively. These clinical and immunohistochemical findings were strongly suspected the malignant transformation of SFT from benign. He was treated with radiotherapy, and a response was observed.