Focal venous malformations and risk of muscle involvement: A retrospective cohort study

Background: Venous malformations (VMs) are the most common vascular malformations. VMs can be classified as focal, multifocal, or diffuse types. Focal venous malformations with muscle involvement is not well defined.Objective: The aim of our study was to characterize characteristics of focal VMs and classify them based on position that are associated with invasion of muscle.Methods: This is a single-center, retrospective review of patients treated for focal VMs between February 2021 and February 2022.Results: We assessed 26 patients focal VMs with 47 lesions; 18 (69%) were unifocal, 3 (12%) were dual-focal and 5（19%）were multifocal type VMs, and 29（62%) were intramuscular VMs. Of all focal VMs, 32 (68%) lesions arose in the extremities, 10 (21%) in the head and neck region and 5 (11%) in the torso. The three groups were no statistical difference for the intramuscular VMs, 19 (68%) arose in extremities, 6 (21%) in the head and neck region and 3 (11%) in the torso. But the lower limbs intramuscular VMs had a signifificantly elevated risk of focal VMs(relative risk [RR],1.7; 95% confidence interval [CI], 1.148-2.394). Limitations: Retrospective, single-institution study.Conclusion: Intramuscular involvement of the body should be considered in focal VMs. The lower limbs intramuscular VMs had a signifificantly elevated risk of focal VMs.