A proposal for a revision of the phlebographic classification of congenital venous malformations.

Background: Venous malformation (VM) is the most frequent type of congenital vascular malformation. In terms of functional outcome local sclerotherapy remains the most important therapeutic tool. For planning and correct estimation and prevention of complications, an exact anatomical classification of the VM is crucial. Not only the drainage, as assessed in the established classification, but also the phlebographic aspect of the internal VM structure itself plays a decisive role. In order to integrate this aspect, we aim to validate a proposal for a revised phlebographic VM classification distinguishing non-lacunar (a) and lacunar (b) types.

Methods: We retrospectively analyzed all patients with VM in whom a direct puncture phlebography was performed in our clinic between 2009 and 2018 to assess morphology and flow characteristics. Phlebographic assessment included: (I) differentiation of non-lacunar vs. lacunar type; (II) drainage assignment according to the existing classification; (III) adjusted classification combining both. Inter-reader agreement was measured in percentage as well as by the Cohen's kappa coefficient (κ).

Results: Overall 26 patients were classified as non-lacunar (a) and 41 patients as lacunar (b) VM. For this categorization, inter-reader agreement was 96% (κ=0.91). Classical Puig classification into types I, II, III and IV showed 87% inter-reader agreement (κ=0.78). For the adjusted classification adding the non-lacunar or lacunar characteristic to type I-IV an agreement of 82% (κ=0.77) was achieved.

Conclusions: Phlebographic differentiation into non-lacunar and lacunar VM is feasible and reliable to distinguish phenotypic subgroups of patients with VM. We therefore propose to integrate this parameter of the internal VM structure into the existing classification.