Introduction: Olfactory neuroblastoma, also known as esthesioneuroblastoma (ENB), is a malignant neoplasm with an unpredictable natural history of progression. Currently, the widely accepted treatment is inductive chemotherapy, with or without surgery followed by radiotherapy. Since data on genetics and molecular alterations of ENB are understudied, there is no standard of care on molecular targets. Neuroendocrine tumors commonly express a somatostatin receptor that is highly expressed by ENB. There have been promising results using peptide receptor radionuclide therapy (PRRT) known as 177Lu-DOTA-TATE for treatment of neuroendocrine tumors utilizing the somatostatin analogue, Octreotate, binding to these somatostatin receptors on the tumor. We present complex neuroradiological and neuropathological changes associated with 177Lu-DOTA-TATE treatment for a patient with a highly treatment resistant

Methods: After a history of 5 surgeries and many chemotherapy and immunotherapy attempts, a 60-year old patient with an ENB--Hyam's grade 3--was treated with 5 induction cycles (intravenous injections) of 177Lu-DOTA-TATE and monitored with 68Ga-DOTATOC PET/CT.

Results: After 4 induction cycles, the patient underwent surgical resection of a recurring frontotemporal ENB in the anterior temporal lobe in April 2017. Thereafter, he underwent his fifth induction cycle. While post-operative MRI showed only a solitary focus of dural disease along the right parietal convexity, concurrent 68Ga-DOTATATE PET/CT showed evidence of multiple dural implants, but no evolution of ENB. Neuropathological evaluation confirmed radiation necrosis to the ENB after pathology specimens were obtained from his April 2017 surgery. There has been no further progression or exacerbation of the patient's disease.

Conclusions: In this report we describe imaging changes associated with PRRT utilizing 177Lu-DOTA-TATE for recurring ENB. This is the first report describing neuropathological changes associated with this new treatment. With promising results of 177Lu-DOTA-TATE for systemic neuroendocrine tumors, we believe this novel treatment paradigm may improve the prognosis and control for patients with ENB.

Patient Care: Our approach to treating highly aggressive and treatment resistant esthesioneuroblastomas will allow for better quality of life. This novel treatment paradigm has been successfully used in systemic neuroendocrine tumors expressing the same somatostatin receptor that ENB's do. Further trials are necessary to ascertain the efficacy of this treatment.

Learning Objectives: 1. To learn about the highly treatment resistant nature of esthesioneuroblastoma 2. To understand peptide receptor radionuclide therapy, specifically 177Lu-DOTA-TATE 3. To learn about the newfound neuropathological and radiological effects as a result of 177Lu-DOTA-TATE 4. Identify a new modality of imaging for ENB

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