GISTosis Unveiled: FDG PET/CT in Early Postoperative Peritoneal Spread of Ileal GIST

Gastrointestinal stromal tumours (GISTs) are mesenchymal neoplasms with a known propensity for hepatic and peritoneal metastasis. Tumour rupture, whether spontaneous or iatrogenic, is a significant adverse prognostic factor associated with peritoneal dissemination and GISTosis. We report a case of early postoperative peritoneal sarcomatosis following resection of an ileal GIST. Conventional imaging demonstrated nonspecific peritoneal abnormalities, while microbiological evaluation was negative for an infective aetiology. Subsequent 18 F-FDG PET/CT (fluoro-deoxy glucose positron emission tomography/computed tomography) revealed extensive metabolically active peritoneal and omental deposits, consistent with peritoneal sarcomatosis. These findings were suggestive of tumour dissemination likely related to intraoperative tumour rupture. The patient was managed with targeted therapy using imatinib. This case highlights the aggressive biological behaviour of small bowel GIST and emphasises the crucial role of FDG PET/CT in early detection, accurate disease characterisation, and guiding timely therapeutic decision-making in postoperative settings.