# Renal Solitary Fibrous Tumor With Local Recurrence Following Complete Surgical Resection: A Case Report

## TL;DR

A rare case of kidney tumor recurrence after surgery highlights the unpredictable nature of renal solitary fibrous tumors.

## Contribution

Reports a rare case of local recurrence of renal solitary fibrous tumor following complete surgical resection.

## Key findings

- An 81-year-old woman had a malignant renal solitary fibrous tumor confirmed by histopathology and immunohistochemistry.
- Local recurrence was detected one year after surgery despite initial negative imaging.
- The case underscores the need for long-term follow-up in managing renal solitary fibrous tumors.

## Abstract

Solitary fibrous tumor (SFT) is a rare mesenchymal neoplasm that most commonly arises in the pleura. Renal SFT is extremely uncommon, and local recurrence after complete surgical resection is rarely reported. In our case, an 81-year-old woman underwent laparoscopic radical nephrectomy for an incidentally detected left renal mass. Histopathological and immunohistochemical analysis confirmed a malignant SFT, with STAT6 and CD34 positivity, and classified it as intermediate risk according to the modified Demicco model. Despite negative imaging at six months, local recurrence was detected one year postoperatively and confirmed by biopsy. Renal SFTs may demonstrate unpredictable biological behavior, including local recurrence after apparently complete resection. Close and long-term follow-up is essential for optimal patient management.