Bilateral Orbital Soft-Tissue Metastases from Renal Neuroendocrine Tumor: Successful Theranostic Application of 68 Ga/ 177 Lu-DOTATATE with Improvement of Vision.

A gratifying clinical response obtained in the setting of bilateral orbital metastases from renal neuroendocrine tumor is reported. Methods: A 53-y-old man diagnosed with renal neuroendocrine tumor (MIB1 index, 4%), with symptoms of skeletal and abdominal pain, proptosis, and a decrease in vision of the left eye, was found to harbor bilateral orbital soft-tissue lesions on 68 Ga-DOTATATE PET/CT and MRI in addition to widespread metastatic skeletal lesions and metastatic lymph nodal disease. Despite radiotherapy to the left eye (20 Gy) and long-acting octreotide therapy for 18 mo, his symptoms worsened, with an increase in serum chromogranin A level, and he was considered for 177 Lu-DOTATATE peptide receptor radionuclide therapy (PRRT). Results: There was a significant improvement in skeletal pain, proptosis, and vision after 4 cycles of PRRT (cumulative dose of 22.2 GBq), stable disease on scanning, and a decrease in serum chromogranin A (from 150 to 36.39 ng/mL), with progression-free survival at 18 mo. Conclusion: PRRT through theranostic application of 68 Ga/177 Lu-DOTATATE was thus helpful in this uncommon clinical setting.