Retroperitoneoscopic resection of a jejunal gastrointestinal stromal tumor masquerading asan adrenal incidentaloma; a unique reminder of the importance of clinical decision-making

Although gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors, they are rare, especially those arising from the small bowel. Adrenal incidentalomas (AI) are much more common, the majority of which are non-functional. Radiological features largely guide the diagnosis and management of both types of tumors and due to investigative limitations, gastric and small bowel GISTs can be misdiagnosed on imaging as AI, especially if present in the left upper quadrant. A 58-year-old male was referred for the management of a left adrenal incidentaloma following investigations for weight loss. An adrenal protocol computed tomography demonstrated a 32-mm left adrenal mass without atypical features. Investigations including gastroscopy and adrenal biochemistry were normal. Positron emission tomography revealed a highly avid adrenal mass suggesting a non-functioning adrenal carcinoma. A prone retroperitoneoscopic left adrenalectomy was per-formed, but no abnormal adrenal lesion was found. An intraoperative re-review of imaging, further retroperitoneoscopic exploration of the retroperitoneum and the peritoneum identified a pedunculated tumor attached to the proximal jejunum. The tumor was successfully resected retroperitoneoscopically. Histopathology revealed a GIST. No previous reports of a retroperitoneoscopic GIST resection have been published nor has a misdiagnosis of a small bowel GIST as an adrenal tumor been published. This highlights the importance of intraoperative correlation of imaging and intraoperative findings and exploring alternative diagnoses when encountering discordance. Attention to detail is required when tumors are solely radiologically diagnosed without additional confirmatory investigations, especially so in potentially anatomically unclear regions.