Olfactory Neuroblastoma: The Adjunctive Role of Somatostatin Agonists After Surgery

Clinical Case: A 54 years old woman who had a right-sided nasal obstruction, rhinorrhea, and sometimes purulent discharge in 2016. In 2002 she had hyperthyroidism by Graves disease and treated for two years with remission after that. The examination of the nose revealed a dark red bleeding mass filling the area from the right nasal cavity to the nasopharynx. The biochemical and serum hormonal values were in a normal range. Urine 5 -HIIAA was 2,5 mg/24h. MRI T1 and T2-weighted images revealed a mass of 4,1 x 4,2 cm, slightly higher signal in T2 and isointense in T1, that extended into the right nasal cavity and ethmoidal sinus. A biopsy was performed, which revealed neuroendocrine characteristics. Octreotide scan with SPECT showed an intense nasal uptake. Right internal maxillary artery embolization was performed. In the next two days, the tumor was resected through a right lateral rhinotomy. Histopathological examination revealed olfactory neuroblastoma, score low grade, ki67<2%. Positive immunohistochemical staining to CD56, synaptophysin, NSE, GFAP, calretinin, S-100 and chromogranin A, and negative staining to cytokeratins (CKs) (CKAPM, CKBPM, CK8/18), CD99 and Bcl-2. The resection was almost total, with no octreotide scan uptake. The post-MRI revealed a minimal residual lesion. Lanreotide treatment was introduced after surgery; the dose was 120 mg every four weeks the first year and every 8 weeks after that. No secondary effects or biochemical alterations were observed. In 2020 the octreotide scan again revealed nasal uptake showing local recurrence. This local recurrence was treated with surgery, followed by lanreotide 120 mg every 4 weeks. No residual disease has been found afterward. Discussion: A limited number of cases have been reported, but none of them were treated with somatostatin agonists. As in our case, the majority of the ON is slow-progressive and non-secreting. The patients mainly complain of local symptoms such as nasal congestion. Surgery is considered to be the first-line treatment for localized disease. In the case of a close margin of the lesion or a residual tumor, the recommendation was radiotherapy or chemotherapy for more advanced disease. We confirmed that the tumor expressed somatostatin receptors. The octreotide scan has been found helpful in the diagnosis and follow-up. We treated the patient with lanreotide with no progression of the disease for three years. Local recurrence could be treated with surgery, following by lanreotide treatment, no residual disease has been found to date. The somatostatin analogs may be a useful adjuvant therapy for stable disease without evident residual disease after surgery.