The "long-tongue" sign: a new perspective on magnetic resonance imaging images of medullary ganglioglioma.

Medullary ganglioglioma (GG) is an exceptionally rare tumor of the central nervous system, and its early diagnostic markers and prognostic indicators remain poorly defined. In this multi-center retrospective study, we reviewed 13 cases of histopathologically confirmed medullary GG to investigate their magnetic resonance imaging characteristics and assess the potential correlation between imaging features and BRAF V600E mutation status. A novel imaging feature-termed the "long-tongue" sign-was identified, characterized by patchy enhancement along the dorsal aspect of the medulla on contrast-enhanced T1-weighted imaging. This feature was observed in 11 out of 13 patients (84.6%). Among the 8 cases with available molecular data, 7 (87.5%) tested positive for the BRAF V600E mutation, and 6 of those (75%) also exhibited the "long-tongue" sign. Although the statistical association between this imaging feature and BRAF mutation did not reach significance (P>0.05), the high rate of co-occurrence suggests a potential biological link that warrants further investigation in larger studies. All patients underwent surgical resection, with gross- or near-total removal achieved in most cases (10/13, 76.9%), reflecting the feasibility and generally favorable outcomes of surgical management for low-grade lesions. These findings highlight a previously unrecognized imaging pattern that may aid early identification of medullary GG and offer preliminary insight into its molecular basis. Further studies with larger cohorts are needed to validate these results.