Early rare recurrence of a huge renal solitary fibrous tumor: Case report and review of literature

Abstract

Solitary fibrous tumor (SFT) is a spindle cell neoplasm of mesenchymal origin. First reported in 1931, the pleura is the most common localization of SFT, and it’s exceptionally rare in the kidney. Overall, it represents less than 2% of all soft tissue tumors. In most cases, renal SFT (rSFT) presents with hematuria, flank pain, and a palpable mass. To our knowledge, less than 112 cases of rSFT have been reported. We report a case of rSFT of a 30-year-old male thought to be a renal cell carcinoma (RCC). Radical nephrectomy (RN) was done to remove a large right-sided mass invading the inferior vena cava. Immunohistochemistry confirmed the diagnosis of SFT showing positivity for CD34, CD99, and Bcl-2 protein, with no staining for cytokeratin. A post-operative CT (15 months) showed tumor recurrence in the renal compartment with huge inferior vena cava thrombus extending to the external iliac veins. With this case, we illustrate and highlight the importance of this diagnosis because of the uncertain biological behavior and prognosis of these tumors.

Keywords

• kidney cancer
• ؛immunohistochemistry
• ؛solitary fibrous tumor