Metachronous Malignant Solitary Fibrous Tumor of Kidney: Case Report and Review of Literature

Abstract

Solitary fibrous tumors are well described in the pleura, but rare extra-pleural neoplasms have been reported. We describe a patient with a solitary left renal fibrous tumor who after undergoing a nephrectomy, presented 8 years later with a contralateral metachronous solitary fibrous tumor. Malignant metastatic extra-pleural solitary fibrous tumors are extremely rare, and to our knowledge, this is the first case of contralateral recurrence of solitary renal fibrous tumor. The patient underwent a robotic assisted partial nephrectomy of the right renal mass. Both tumors showed overlapping histopathology.

Keywords: CD34; CT, Computerized Tomography; Cr, creatinine; HPF, High Power Field; Hemangiopericytoma; Metachronous metastasis; NCCN, National Comprehensive Cancer Network; SFT, solitary fibrous tumor; Solitary fibrous tumor.

Figure 1

Large 12 cm × 10 cm enhancing left renal mass with central necrosis and calcification on initial presentation (black arrow).

Figure 2

Eight years post left radical nephrectomy with new 4.3 cm enhancing right renal mass with necrotic foci (black arrow).

Figure 3

Histopathology of the resected metachronous right kidney lesion revealing spindle cell architecture, cytological atypia, and diffuse CD 99 staining on immunohistochemistry consistent with malignant SFT.