Wall Derived Atypical Type II Endoleak 10 Years After Endovascular Aneurysm Repair: Intra-operative and Histopathological Evidence of Vasa Vasorum Mediated Haemorrhage

Abstract

Introduction

Wall derived atypical type II endoleak (aT2EL) is characterised by aneurysm sac enlargement with delayed phase mural enhancement in the absence of conventional branch feeders. Comprehensive clinicopathological correlation is rare.

Report

A 76 year old man presented with progressive sac growth 10 years after infrarenal endovascular aortic repair (EVAR) with previous inferior mesenteric artery (IMA) and right internal iliac artery embolisation at the index procedure, and additional embolisation for a recurrent IMA related type II endoleak at five years. Pre-conversion computed tomography angiography (CTA) revealed no patent IMA or lumbar arteries but showed patchy delayed phase enhancement of the mural thrombus. Open conversion demonstrated multiple sites of diffuse oozing from the luminal (intimal) surface of the aneurysm wall without branch inflow or endograft defect. Histopathology identified a distinctive triad: extensive intimal denudation, media exposure with luminally oriented microvessels, and adventitial vasa vasorum proliferation. Targeted sacotomy with selective oversewing was performed while preserving the endograft. Recovery was uneventful. Follow up CTA at three years demonstrated sustained sac reduction without residual endoleak.

Discussion

Integration of delayed phase imaging, direct intra-operative luminal wall oozing, and a histopathological triad supports a vasa vasorum mediated mechanism for wall derived aT2EL. Recognising this pattern can guide surgical planning towards sacotomy with selective haemostasis and endograft preservation, and supports incorporating delayed phase CTA or time resolved contrast enhanced magnetic resonance angiography into post-EVAR surveillance.