Somatic TEK Mutation Identified in a Patient with Calvarial Venous Malformations.

Background: Calvarial venous malformations (VMs) are rare and genetically understudied. While somatic TEK receptor tyrosine kinase (TEK) mutations drive sporadic VMs, their role in scalp-calvarial VMs is unknown. We report the first pediatric case of a calvarial VM with a pathogenic somatic TEK mutation and its molecular implications. Methods: A 16-year-old female with a symptomatic parietal scalp VM underwent neurosurgical resection. Exome sequencing was performed on both lesional and blood DNA. Single-cell RNA sequencing (scRNA-seq) data from normal brain vasculature were analyzed for TEK expression and pathway enrichment. Results: A novel somatic TEK L914F mutation (chr9:27212760-C-T [GRCh38]), absent in germline DNA and population databases, was identified and predicted to be deleterious (CADD: 24). scRNA-seq data analysis revealed TEK enrichment in endothelial cells, particularly in fetal and arterial subtypes, and implicated angiogenesis and PI3K/Rho signaling as potential downstream phenotypic and molecular consequences. Conclusions: This first pediatric scalp VM with a somatic TEK L914F mutation expands the phenotypes associated with TEK-related vascular anomalies. These findings emphasize the role of somatic TEK mutation in diverse VMs and support genetic testing in sporadic cases. Further studies are needed to define therapeutic targets.