Insulinoma, a rare neuroendocrine tumor characterized by hyperinsulinemia, often leads to fasting hypoglycemia. As insulinoma is exceptionally rare in juveniles, atypical presentations such as ovarian insulinomas are also exceedingly rare. We report a case of ovarian insulinoma in a female teenager diagnosed with the assistance of 177Lu-DOTATATE whole-body scan.

This case describes a 19-year-old female with recurrent weakness, fainting, and hypoglycemia, initially attributed to a Sertoli tumor in the right ovary. Further investigations revealed a suspected insulin-secreting neuroendocrine tumor in the uterus. Imaging confirmed a malignant ovarian tumor, histologically diagnosed as a grade 2 neuroendocrine tumor. Treatment involved discharge with Octreotide long-acting release (LAR) and planning for conservative surgery followed by adjuvant chemotherapy.

Although insulinoma diagnosis depends on biochemical markers, functional nuclear medicine imaging assists in localizing tumor. 177Lu-DOTATATE can provide valuable insights into somatostatin receptor (SSTR) expression even when SSTR immunohistochemistry testing is unavailable, thereby aiding in prognosis prediction. Since it uses SPECT imaging, 177Lu-DOTATATE can be utilized in limited-resource settings where PET cameras are not accessible. Furthermore, while surgery remains the primary treatment for insulinoma, peptide receptor radionuclide therapy (PRRT) using 177Lu-DOTATATE showing promise in metastatic and inoperable condition.

177Lu-DOTATATE holds significant potential as a theranostic agent, serving both diagnostic and therapeutic purposes. Beyond its established role in neuroendocrine treatment, it can be particularly valuable for assessment of SSTR expression and tumor localization, especially in resource-limited settings where neither SSTR immunohistochemistry nor PET-based radiotracers are available. This dual utility supports its broader clinical application in managing rare and complex neuroendocrine tumors such as insulinoma.