Multiple solitary fibrous tumors of the pleura with multicentric and unilateral involvement: a case report

BACKGROUND: Solitary fibrous tumor of the pleura (SFTP) is a mesenchymal tumor. Patients with SFTP generally have only one lesion. We herein report an extremely rare case of multiple SFTPs that were multicentric and unilateral. CASE PRESENTATION: The patient was a 21-year-old asymptomatic young man who was referred to our hospital due to abnormal shadows on a chest X-ray. Computed tomography showed 6 tumors of heterogeneous sizes in the left thoracic cavity. The tumors were suspected to be multiple benign or low-grade malignant thoracic tumors, and tumor resection was performed. The tumors had almost the same appearance, with uniform fibroblastic spindle cell proliferation, and arose from the pleura in microscopy. Immunohistochemical staining revealed that the tumor cells were positive for CD34, CD99, Bcl-2, and STAT6. Based on these findings, the tumors were diagnosed as multiple SFTPs with multicentricity. At 1 year and 6 months after the first surgery, 2 new lesions were found above the diaphragm, and these were resected. These tumors were arose from the pleura with a fibrous capsule structure. Their pathological findings were identical to the initial tumor without evidence of malignant transformation. CONCLUSION: We experienced an extremely rare case of multiple SFTPs with multicentric and unilateral lesions.