Scoliosis in children and adolescents with NF1 and plexiform neurofibromas: a preliminary study of clinical phenotypes and eosinophil and basophil features

Scoliosis is an important musculoskeletal complication in children and adolescents with neurofibromatosis type 1 (NF1), particularly among those with plexiform neurofibromas. Although clinical phenotypes such as paravertebral tumor involvement may contribute to spinal deformity, they do not fully account for the heterogeneity in scoliosis occurrence. Beyond these visible phenotypes, eosinophils and basophils may be biologically relevant to immune regulation, fibrosis, and skeletal homeostasis. This preliminary study investigated whether selected peripheral granulocyte characteristics, together with clinical phenotype, were associated with tumor-associated scoliosis. This retrospective study included 31 children and adolescents with NF1 and plexiform neurofibromas who were treated in the Department of Otolaryngology, Head and Neck Surgery at Beijing Children’s Hospital, Capital Medical University, between January 2022 and December 2025. Patients were classified into a scoliosis group (Cobb angle ≥ 10°, n = 13) and a non-scoliosis group ( n = 18). Demographic characteristics, clinical phenotypes, and peripheral-blood eosinophil and basophil indices were analyzed. Variables with p < 0.05 in univariable analysis were entered into multivariable logistic regression models, with Firth penalization used to reduce small-sample bias. Receiver operating characteristic curve analysis was used to assess discriminatory performance. Paravertebral infiltration ( p = 0.017) and eosinophil category ( p = 0.033) were significantly associated with scoliosis, whereas basophil-related indicators and the other variables were not. After Firth penalization, paravertebral infiltration remained independently associated with higher odds of scoliosis (adjusted odds ratio (OR) 8.00, 95% confidence interval (CI) 1.43–65.7; p = 0.017), while higher eosinophil levels remained independently associated with lower odds of scoliosis (adjusted OR 0.18, 95% CI 0.03–0.89; p = 0.035). Eosinophils showed moderate discriminatory performance (area under the receiver operating characteristic curve (AUC) 0.724), whereas basophils showed limited performance (AUC 0.613). Paravertebral infiltration and peripheral eosinophil level were independently associated with scoliosis in children and adolescents with NF1 and plexiform neurofibromas. Integrating clinical phenotype with selected peripheral granulocyte characteristics may provide a useful exploratory framework for risk stratification and for better characterizing the heterogeneity of scoliosis in this population.