Volumetric analysis of olfactory neuroblastoma skull base laterality and implications on neck disease

Objective: To determine if the laterality of primary tumors in patients with olfactory neuroblastoma (ONB) influenced the pattern and development of neck disease. Methods: Using a retrospective cohort study design from 1994 to 2015, the primary tumors of patients who either presented with or developed neck disease were volumetrically analyzed using iPlan software (version 3.0.0, BrainLAB, Feldkirchen, Germany) by two independent observers. Agreement of volume-derived sidedness was assessed with a kappa statistic, whereas agreement in volume-derived degree of tumor laterality was evaluated with an intraclass correlation coefficient. A one-sample t test was used to assess the difference in dominant percentage between the two observers. Results: Sixty-one patients with histological diagnosis and treatment of ONB at our institution were identified. Twenty-four patients exhibited neck involvement, 13 of whom could be volumetrically analyzed. Tumors that were greater than 75% eccentric to one side all exhibited contralateral disease, whereas the majority of unilateral neck disease was associated with relatively midline masses. Within the entire cohort, ipsilateral level 2 lymph nodes displayed the highest involvement (83%, 20 of 24), followed by ipsilateral level 1 (54%, 13 of 24), contralateral level 2 (46%, 11 of 24), contralateral level 1 (21%, 5 of 24), and ipsilateral level 3 (21%, 5 of 24). Conclusion: Ipsilateral neck involvement frequently was observed; however, the degree of ONB primary site laterality did not appear to have implications on the development of contralateral neck disease. Therefore, when considering elective therapy to the neck, ONB laterality should not be used to justify unilateral neck treatment. Level of Evidence: 4. Laryngoscope, 128:864–870, 2018.