HLS is considered a rare vascular lesion with a diffuse lesion or a braid-like appearance that can be detected by angiography, and further intravascular examination, such as IVUS and coherence tomography (OCT), helped to confirm the multiple intraluminal channels or honeycomb structure, which can also be described as having a ‘swiss cheese-’, a ‘spider web-’, or a ‘Lotus root-like’ appearance . IVUS and OCT are helpful and essential for diagnosing HLS . HLS was mostly reported in the coronary artery, but there were also some case reports of HLS being located in the carotid artery and renal artery [3, 5, 6]. The aetiology of HLS is still not clear. Previous studies have reported that it can be caused by spontaneous recanalisation after thrombotic events, including in situ thrombosis and embolic thrombus. Thrombosis can be secondary to vasculitis caused by Kawasaki disease, antiphospholipid syndrome and vasospasm [1, 7,8,9,10]. With the application and development of intravascular examination, more and more HLS was found, and most of its causes were thought to be recanalisation of the in situ thrombus and embolic thrombus . Kazuoki et al. reported serial coronary angiography of a post-emergent coronary artery bypass grafting patient and found that occlusive thrombus in the left circumflex artery (LCX) was recanalised spontaneously after two years of follow-up. A lotus-root appearance was then confirmed by OCT, which provided the direct evidence that the multiple communicating channel structure represented spontaneous recanalised lesions after the thrombotic occlusions . A similar manifestation was also found in an effort angina patient and confirmed by high-resolution intravascular ultrasound (HR-IVUS) . Despite recanalization, most HLS lesions significantly affect blood flow, with an FFR value < 0.8 . Therefore, positive intervention therapy was suggested for HLS lesions. Previous studies reported different treatment strategies, including drug-eluting stent (DES) implantation, drug-coating balloon and bioresorbable vascular scaffold [5, 13, 14]. However, stent implantation, which compresses both the septa and cavities, may be associated with side branch compromise or occlusion .
To our knowledge, this is the first case of HLS on the basis of atherosclerosis in the renal artery. The renal artery multiple luminal surrounded by fibrous tissue was demonstrated by IVUS, and no intact vascular wall of branches was shown in intravascular imaging. The properties of the lesions could not be fully identified. Upon consideration of multiple atherosclerotic risk factors, including age, diabetes and hyper-lipidaemia, we surmised that the stenosis of the left proximal renal artery resulted from atherosclerosis. Based on serious stenosis of the proximal artery, the decreased velocity of distal blood flow led to thrombus formation, which was associated with renal infarction. The thrombus was recanalized and finally formed HLS in his renal artery as a result of mismanagement in the acute phase. In addition, three months of follow-up showed that the patient had no complaint after stent implantation, which also verified our previous speculations.
In conclusion, the mechanism and formation of HLS are still unclear. This malformation can be found not only in the coronary artery but also in the renal artery. Detailed patient histories, long-term follow-up, angiogram, and intravascular imaging data may offer a deeper understanding of HLS in future clinical practice.