Intraoperative gamma probe detection of lymph node recurrence of insulinoma.

Insulinomas are rare endocrine tumors that are mostly sporadic, benign, and small. Preoperative radiography diagnosis may be difficult. Intraoperative palpation and ultrasound remain the gold standard for detection and planned resection. Recent studies find intraoperative gamma-probe localization as a good technique for identifying primary neuroendocrine tumors. We report a case of a 75-year-old woman with functioning lymph node recurrence of a malignant insulinoma. Spleno-pancreatectomy was performed in order to treat the malignant insulinoma. Clinical, biochemical, and radiological examination confirmed the total excision of the primary lesion. However, clinical symptoms appeared 9 months later. Octreo-scan, abdominal CT, and biochemical study showed lymph node recurrence and four hepatic metastases. Surgery was performed after two [111In-DTPA] octreotide scans. Intraoperative gamma probe detection was planned in order to localize a small latero-aortic lymph node recurrence. Intraoperative count rates were high in para-aortic tissue. Para-aortic lymphadenectomy and metastasectomy were carried out. Ex-situ count rates and histological examination confirmed the recurrence. Six months later clinical and biochemical studies and scans remain negative for recurrence. Intraoperative [111In-DTPA] octreotide gamma probe examination may be a useful tool in the surgical approach to insulinoma recurrence.