Cell-free DNA obtained during sclerotherapy as a method for molecular analysis of venous and lymphatic malformations

Objective Vascular malformations (VMs) are usually caused by postzygotic somatic mutations in genes regulating tissue growth. The mutational discoveries in VMs have provoked a transition in the diagnosis, classification, and management of VMs. Therefore, molecular analysis of VMs is more frequently performed, which generally requires interventional-obtained lesion tissue. We hypothesized that cell-free DNA (cfDNA) obtained from the VM during sclerotherapy could be a minimally invasive alternative for specimen collection for molecular analysis. Methods In a prospective case series, blood and lymph fluid were collected locally from venous, lymphatic, and combined malformations during sclerotherapy. cfDNA was isolated from the collected samples and analyzed for VM-associated genes with next-generation sequencing. If a mutation could not be detected in lymphatic malformations, the cfDNA was analyzed using a precise cfDNA assay, allowing for a lower detection limit of 0.10%. Results Somatic mutations were detected in cfDNA of patients with venous (5/14) and lymphatic malformations (5/8). However, in three patients with lymphatic malformations, the somatic mutation could only be detected using the cfDNA assay. We did not detect any somatic mutations in two patients with combined malformations. Conclusions Somatic mutations were detected in the cfDNA obtained during sclerotherapy of venous and lymphatic malformations and, therefore, could serve as an alternative for tissue biopsies. Particularly for deep-positioned VM or other unenforceable tissue biopsies, cfDNA provides a solution. The development of a cfDNA assay for all VM-associated genes may further enhance molecular analysis. The findings of this study are a valuable contribution to a field in which genetics is becoming increasingly important and where molecular diagnostics are more frequently performed.