Solitary Fibrous Tumor of the Mesentery of the Small Intestine: A Rare Case Report.

Solitary fibrous tumors (SFTs) are rare spindle cell neoplasms of mesenchymal origin, most commonly originating from the pleura. The discovery of the NAB2-STAT6 gene fusion has enabled more accurate diagnosis, particularly in extrapleural locations. We report a rare case of a 50-year-old woman presenting with localized abdominal pain, who showed a 46-mm heterogeneous mass in the left abdomen on contrast-enhanced CT; laparoscopic exploration identified a pedunculated tumor arising from the jejunal mesentery, located 50 cm distal to the ligament of Treitz. Segmental resection of 15 cm of the jejunum with the associated mesentery was performed. The tumor measured 55 × 45 × 30 mm and was confined to the mesentery, with no invasion of the bowel wall. Histopathological examination revealed proliferation of spindle cells within a collagenous stroma, and immunohistochemistry confirmed strong nuclear STAT6 and cytoplasmic CD34 positivity, while c-Kit, DOG1, Desmin, and S-100 were negative, establishing the diagnosis of SFT. The patient's abdominal pain resolved completely following resection. This case highlights the diagnostic challenges of mesenteric SFTs and underscores the importance of complete surgical resection with intact borders and immunohistochemical analysis in securing an accurate diagnosis and favorable outcome.