Clinicopathological Characteristics and Recurrence Patterns of Olfactory Neuroblastoma: A 15-Year Tertiary Center Case Series.

Objectives: Olfactory neuroblastoma (ONB) is a rare malignant tumor of the sinonasal tract with heterogeneous clinical behavior and recurrence potential. Due to its low incidence, prognostic factors and optimal treatment strategies remain incompletely defined. The objective of this study was to describe the clinicopathological characteristics, treatment approaches, and recurrence patterns of ONB over a 15-year period at a tertiary referral center. Methods: A retrospective case series and literature review were performed. Medical records of nine patients with histologically confirmed ONB treated between 2007 and 2022 were reviewed. Demographic characteristics, presenting symptoms, imaging findings, Hyams histologic grade, treatment modalities, and follow-up outcomes were analyzed. Diagnosis in every case rested on characteristic morphology together with a full neuroendocrine immunohistochemical panel, and Hyams grade was assigned on the definitive resection specimen. Variables that were not uniformly documented across the 15-year archive-clinical stage, surgical margin status and the anatomical compartment of recurrence-were deliberately not imputed and are reported as unavailable. Results: Patients ranged in age from 18 to 61 years (mean 41.3 ± 12.4 years; median 42 years), with a male predominance (6/9, 66.7%). The most common presenting symptoms were nasal congestion, headache, and nasal mass. All patients underwent surgical resection with curative intent, predominantly through endoscopic endonasal approaches, followed by adjuvant chemoradiotherapy. Within a uniform, protocol-defined posttreatment observation window of 3 years (median follow-up 36 months), tumor recurrence occurred in 4 of 9 patients (44.4%), and 5 of 9 patients (55.6%) remained free of documented recurrence. Recurrence was observed across different Hyams grades, including grade I tumors, without a statistically significant association between histologic grade, age, or gender and recurrence. Conclusions: ONB demonstrates variable clinical presentation and recurrence patterns, even following multimodal treatment. Histologic grade alone may not reliably predict recurrence in small cohorts. Recurrence despite low-grade histology and uniformly administered chemoradiotherapy supports grade-, stage-, and margin-adapted rather than uniform adjuvant strategies, and structured surveillance continued well beyond 5 years.