Clinical and Imaging Phenotype of Schwannomatosis in Children, Adolescents and Young Adults

Background/Objectives: To characterize the clinical and imaging phenotypes of schwannomatosis (SWN) in children, adolescents, and young adults (AYAs). Methods: This single-center retrospective cohort study included patients (age ≤ 25 years) with suspected SWN with archived magnetic resonance imaging (MRI) at Johns Hopkins between 2020–2026. Clinical characteristics, genetic testing results, and tumor imaging (including anatomic distribution), and treatment approaches were reviewed. Descriptive statistics were performed. Results: In total, thirty-eight patients with suspected SWN were identified (median age 20 years, range 6–25; 32% female). NF2-related SWN was the most common diagnosis (31/38, 82%; de novo: 24/31 (77%) and familial: 7/31 (23%)), followed by LZTR1-SWN (n = 1) and SWN-NOS/NEC (n = 2). A total of four patients (asymptomatic LZTR1 carriers (n = 2) and possible SWN (n = 2)) did not fulfill diagnostic criteria based on craniospinal and whole-body MRI. Familial NF2-SWN demonstrated a trend toward earlier presentation (median 5 vs. 8 years; p = 0.12). Visual manifestations occurred at a younger age than hearing loss (median 8 vs. 16 years; p = 0.053). Imaging burden was high (median 23 MRI/patient (range: 1–60). Bilateral vestibular schwannomas were nearly universal (30/31, 97%). Familial disease demonstrated a trend toward increased cranial meningiomas (86% vs. 54%; p = 0.20), while peripheral schwannomas (43% vs. 67%; p = 0.38) and ependymomas (14% vs. 42%; p = 0.37) were less frequent compared with de novo disease. Operative and non-operative management was documented in 65% (20/31) each. Conclusions: NF2-related SWN is the predominant subtype in a pediatric and AYA patient population and was associated with substantial early tumor burden at a tertiary specialty NF center.