Yun ZOU ,Congzhen QIAO ,Chen HUA ,Xi YANG ,Tianyou WANG ,Yunbo JIN,* ,Xiaoxi LIN,*

1 Department of Plastic and Reconstructive Surgery,Shanghai Ninth People’s Hospital,Shanghai Jiao Tong University School of Medicine,Shanghai 200011,China

2 GE Healthcare China,1 Huatuo Road,Shanghai 201203,China

ABSTRACT Background Despite many advances in the treatment for extracranial arteriovenous malformations (AVMs),they still result in tedious dissection and potential unacceptable complications,particularly in children.Therefore,this study aimed to investigate the efficacy and safety of intralesional interstitial injection of bleomycin for the treatment of children with AVMs.Methods A total of 10 children (6 boys and 4 girls) with AVMs were treated with serial interstitial bleomycin injections between May 2014 and January 2017.Maximum single doses of 15 U and 1 U/kg per session were administered for six sessions at a 1-month interval.Therapeutic effectiveness was evaluated and classified into four categories:complete response (CR),partial response (PR),no response,and worsening at 3 months after the last session.Further clinical follow-up outcomes were classified as improved,stable,or aggravated.Adverse events were recorded according to the Society of Interventional Radiology classification.Results All 10 children completed the sessions and follow-ups.CR occurred in 3 (30%) patients,PR in 6 (60%),and no response in 1 (20%).Minor complications (class A) included maculopapular rash,bulla,vomiting,and hyperpigmentation,whereas no major complications occurred.Conclusion Intralesional interstitial injection of bleomycin is a feasible approach for the treatment of AVMs in children and provides safe and effective outcomes.This method may be an earlier treatment alternative in children to prevent potential destructive progression,considering the serious complications of currently available therapeutic methods.

KEY WORDS Intralesional interstitial injection;Bleomycin;Arteriovenous malformation;Children

INTRODUCTION

An extracranial arteriovenous malformation (AVM) is a congenital high-flow vascular anomaly caused by abnormal communication between the feeding arteries and draining veins without any intervening capillaries[1].AVMs inevitably progress over time and can lead to serious complications,such as disfigurement,bleeding,tissue and structure destruction,ulceration,pain,and cardiac insufficiency[2-3].Despite many advances (radical resection and embolization with various agents) in the treatment of extracranial AVMs,they are still fraught with tedious dissection and potentially severe complications[4-5].

Trends toward less invasive methods are necessary as independent or adjunct treatments for AVMs,particularly in children.Bleomycin is a cytotoxic antitumor agent developed by Umezawa in 1966[6],which was initially effective in patients with lymphatic malformations via an intralesional intravascular approach[7].Recently,many studies have shown positive results and low complication rates in low-flow vascular malformations using intralesional bleomycin injection[8-12].However,bleomycin may not cause a significant vascular injury when administered intravascularly to high-flow vascular malformations[13].We found that bleomycin may have a positive effect on AVM lesions when administered using an intralesional interstitial approach rather than an intralesional intravascular approach[14].However,its effect on children remains unknown.Thus,this study was conducted to investigate the efficacy and safety of intralesional interstitial injection of bleomycin for the treatment of AVMs in children.and size,clinical symptoms and stages,previous medical treatments,treatment responses,complications,and clinical and imaging follow-up.

All patients underwent chest radiography,magnetic resonance imaging (MRI),and digital subtraction angiography (DSA) examinations before the first treatment,with white blood cell count analysis and standardized photography before each session.The lesion size was measured according to the DSA images (Innova 3100;GE Healthcare,Beijing,China) using an automatic calibration method (by T.W.with 5 years of experience).AVMs were staged according to the Schobinger staging system (Table 1)[2].The type of angiographic morphology was determined according to Cho’s classification:typeⅠ,arteriovenous fistulae;typeⅡ,arteriolovenous fistulae;type Ⅲa,arteriolovenulous fistulae with nondilated fistulae;type Ⅲb,arteriolovenulous fistulae with dilated fistulae[15].The post-procedure results of the chest X-ray examination,MRI,white blood cell test,and standardized photography were also recorded.

Table 1 Schobinger classification of AVMs

METHODS

This study was approved by the Institutional Review Board of Shanghai Ninth People’s Hospital,and all patients’ caregivers provided written informed consent before the first treatment.

From April 2014 to April 2016,pediatric patients with extracranial AVMs were enrolled in the study of intralesional interstitial bleomycin injection in our vascular anomaly center.As per the protocol,the inclusion criteria were as follows:1) ages between 2 and 12 years;2) AVMs with maximum anteroposterior,transverse,or cranial caudal diameter of ＜15 cm on angiography;3) main lesions limited to the subcutaneous tissue or muscle;4) no drug contraindications to bleomycin;5) not having received any therapy in the past year.The exclusion criteria were as follows:1) serious underlying systemic diseases that required treatment,including pulmonary diseases (chronic obstructive pulmonary disease,pneumonia,pulmonary fibrosis,and asthma),insufficient cardiac and hepatorenal functions,systemic infection,hemorrhagic tendency or decreasing blood counts,and immunologic diseases (systemic lupus erythematosus,urticaria,and HIV),and 2) not having provided informed consent or not having complied with follow-up strategies.

Bleomycin was interstitially administered to 10 children during the study period.All pre-and post-procedure imaging findings and clinical data of all patients were reviewed,including patient demographics,lesion location

Treatment Procedure

Intralesional interstitial bleomycin was injected percutaneously.All procedures were performed with intravenous sedation or local anesthesia due to the painful nature of the injection.

First,bleomycin (15 U per bottle,Nippon Kayaku Co.Ltd.,Tokyo,Japan) was reconstituted with 10 mL of normal saline to a final concentration of 1.5 U/mL.A peripheral venous access catheter was then placed,and a cardiac monitor to continuously track blood pressure,heart rate,and oxygen saturation (SpO2) was connected during the procedure.The lesion position and depth were determined by reviewing the imaging (DSA and MRI) results of all patients.Bleomycin was then injected into the intralesional interstitial tissue using a 22-G needle.Every puncture was confirmed with no blood withdrawal before injection to ascertain that bleomycin was targeted into the interstitial tissue rather than malformed vessels of the lesion.Bleomycin was then administered until significant resistance or apparent cutaneous color change (from red to white) was observed at the injection site.Subsequent injections with a spacing of 1-2 cm between the injection points were performed until the maximum dose (15 U or 1 U/kg in children weighing ＜15 kg) was reached or the entire interstitial infiltration occurred.Patients were discharged after a 30-min observation period unless adverse events occurred.These procedures were repeated at the 1-month interval,with six procedures in total.

Post-Treatment Assessment

Two radiologists (blinded assessments by assessors with 13 and 11 years of experience) analyzed the imaging response to bleomycin treatment by comparing the final DSA images at 3 months after the last procedure with the baseline DSA images to determine the degree of lesion devascularization through visual assessment by consensus.The degree of lesion devascularization was classified using a four-point grading system (i.e.,Ⅰ:＜50%;Ⅱ:50%-75%;Ⅲ:76%-99%;Ⅳ:100%)[16-20].Three surgeons (X.L.,Y.J.,and H.C.,with 22,10,and 8 years of experience in evaluating AVMs,respectively) evaluated the clinical response (complete resolution,partial resolution,no change,or worsening) 3 months after the last procedure.

The interim treatment outcome was divided into four categories based on both angiographic and clinical responses 3 months after the last procedure[14,25,27-30].Complete response (CR) was defined as 100% lesion devascularization on DSA with complete resolution of initial symptoms and signs;partial response (PR) was established as devascularization of 50%-99% with complete or partial resolution;no response was defined as devascularization of ＜50% without changes or partial clinical resolution,and worsening was defined as a progressive clinical symptom and sign regardless of angiographic devascularization.CR and PR are considered effective therapeutic outcomes of bleomycin[15-21].

All patients underwent periodic clinical follow-up after the interim evaluation 3 months after the last procedure to ensure treatment stability and efficacy.The follow-up period was between the last procedure and the last clinical visit.The outcomes of long-term clinical follow-up were classified into three categories:improved,stable,and aggravated.

Complications were recorded after each procedure and during the follow-up period and were classified as major and minor according to the Society of Interventional Radiology (SIR) reporting standards[22].Minor complications included those that required no treatment or resulted in no consequences (classes A and B),whereas major complications were defined as those that required therapy or caused permanent adverse sequelae or death (classes C,D,E,and F).

RESULTS

Ten children (six boys and four girls) were treated with serial intralesional interstitial injections of bleomycin.All patients were under 12 years of age with a mean age of 5.4 (range,2-10) years.Among these 10 patients,3 (30%) and 7 (70%) were in stagesⅠand Ⅱ,respectively.None of the patients had received any prior treatment for AVMs.According to Cho’s classification[15],8 (80%) and 2 (20%) patients had type Ⅲa and Ⅲb morphology on angiography,respectively.

The mean dose for a single procedure was 13.5±2.6 (range,7.5-15) U,and the cumulative dose for each patient was 85.2±22.2 (range,46.5-135) U.Six procedures were performed in nine patients,whereas nine procedures were performed in the remaining one patient with an 8-month interval between the initial three procedures and the subsequent six procedures.

With regard to the interim therapeutic outcome of bleomycin injection,3 (30%) of 10 patients had CR (Figs.1 and 2),6 (60%) had a PR (Fig.3),and one (10%) had no response,but none experienced worsening.Thus,the effectiveness rate was 90%.The mean follow-up period was 20.2 (range,7-35) months.During the long-term clinical follow-up,the therapeutic outcomes of all 10 (90%) patients remained stable.Detailed results are presented in Table 2.

Fig.3 Patient 5.(A) A pretreatment photo of a 4-year-old girl showing a pulsating mass on the left ear.(B) A pretreatment lateral angiogram of the left external carotid artery showing AVMs (black arrows) with dilated outflow veins (white arrows) on the left ear.(C) A post-treatment photo at 30 months after six procedures (total dose,79.5 U) showing a resolved pulsating mass.(D) A post-treatment lateral angiogram of the left external carotid artery showing 76%-99% lesion devascularization 3 months post-treatment.

Complications included a maculopapular rash,bullae,vomiting,and local or flagellate hyperpigmentation.All complications were classified as minor (class A) as described in Table 3.Most of these adverse events were resolved within 1 month before the next procedure and without special treatment,except for local or flagellate hyperpigmentation.One patient with local hyperpigmentation achieved complete regression within 18 months.Another patient with flagellate hyperpigmentation had incomplete regression after the 13-month follow-up.In addition,all post-procedure results of the chest X-ray and white blood cell tests were normal.

Table 2 Results of intralesional interstitial bleomycin injection in 10 children with AVMs

Table 3 Complications in the study participants

DISCUSSION

Extracranial AVMs have a propensity to grow continually without regression and can cause devastation both functionally and esthetically[2-3,5].The ultimate goal of AVM treatment is to eliminate lesions and increase distal transcapillary flow[16,23].

Fig.1 Patient 2.(A) A pretreatment photo of a 3-year-old boy showing a pulsating mass on the right ear.(B) A pretreatment lateral angiogram of the right external carotid artery showing AVMs (black arrows) on the right ear.(C) A post-treatment photo at 5 months after six procedures (total dose,67.5 U) showing a resolved pulsating mass.(D) A post-treatment lateral angiogram of the right external carotid artery showing 100% lesion devascularization 3 months post-treatment.

However,no single modality has been favored for disease treatment.Current treatments include surgical resection and embolization using various agents[13].Surgical resection plays a limited role because radical resection commonly causes disfigurement or dysfunction and partial resection often leads to recurrence[4,13].

The current agents used for intravascular embolization include n-butyl cyanoacrylate (NBCA),Onyx,polyvinyl alcohol,and ethanol[4,13,24-25].NBCA is often used for preoperative preparation only because it can recanalize and represents a source of infection during follow-up[26-27].Onyx has recently been used for the treatment of extracranial AVMs.De Beule et al.[28]reported a 100% (22/22) response rate,with a 9% major complication rate.However,the recurrence rate was 32% (7/22) during a mean follow-up period of 5.6 years.

Ethanol is a widely available embolization agent and is associated with a low recurrence rate[17].Kim et al.[17]reported a 94% response rate and an 11% long-term recurrence rate with ethanol.However,ethanol is arguably an embolic agent resulting in severe complications,such as pulmonary hypertension,pulmonary embolus,cardiovascular collapse,and nerve injury[13,29].Do et al.[16]reported a major complication rate of 12.5% (5/40).Absolute ethanol should be used only by those who have expertise in this treatment due to its high-risk profile[23].

Thus,an ideal method to treat AVMs is not yet established,especially in pediatric patients.AVMs in children usually have a lower Schobinger stage.The management of children is more limited and controversial,with less functional or cosmetic compromise,because the existing effective treatments have many potential complications,as mentioned above.Therefore,less invasive methods with favorable safety and efficacy profiles are necessary to manage children with AVMs.

Bleomycin has recently been shown as an effective treatment for hemangiomas and low-flow vascular malformations via intralesional intravascular injections.It has low toxicity and degrades DNA in undercoiled strand regions with minimal immunosuppression and myelosuppression[8,30].However,for high-flow vascular malformations,an intralesional intravascular injection of bleomycin cannot immediately induce intravascular obstruction or protein denaturation[13].

In our study,bleomycin solution was administered via an intralesional interstitial injection rather than an intralesional intravascular injection to treat AVMs in children.Effective therapeutic outcomes were observed in 90% (9/10) of children,with a 30% CR rate and 60% PR rate.All complications were classified as minor (class A) according to the SIR classification.

The most severe complication of intravenous treatment reported in oncology patients is pulmonary fibrosis.This complication is associated with the total administered dose[30-31].When the cumulative intravenous dose of bleomycin reached ＞450 mg (approximately 450 U),a pulmonary fibrosis rate of 13% was observed.When the dose was ＜450 mg,the risk of pulmonary fibrosis was 3%-5%[6,30].Only one case of acute pulmonary toxicity has been reported following an intralesional bleomycin injection in a lymphatic malformation in over 2 600 patients in the literature,but no cases of irreversible pulmonary fibrosis have been reported[32-33].In our study,bleomycin was administered intralesionally,interstitially,at a 1-month interval with a maximum dose of 15 U or 1 U/kg per procedure.The total dose was not ＞90 U,except in one patient (Fig.2).No patient had pulmonary fibrosis in our study.

Fig.2 Patient 3.(A) A pretreatment photo of a 10-yearold boy showing a pulsating mass on the lower lip.(B) A pretreatment lateral angiogram of the right external carotid artery showing AVMs (black arrows) on the lower lip.(C) A post-treatment photo at 4 months after the initial three procedures (total dose,45 U) and subsequent three procedures (total dose,90 U) showing a resolved pulsating mass.(D) A post-treatment lateral angiogram of the right external carotid artery showing 100% lesion devascularization 3 months posttreatment.

In addition,flagellate hyperpigmentation was observed in one patient,with a reported incidence of 8%-22%[34].Flagellate hyperpigmentation is usually reversible and persists for ＜1 year[35].However,its underlying mechanism remains unclear.

This study demonstrated a 90% response rate for all AVMs and no recurrences during the follow-up period.Thus,an intralesional interstitial bleomycin injection may be a promising and safe treatment option for children with AVMs.However,the mechanism behind some lesions achieving a CR and others achieving a partial or no response remains unclear.This may be related to the Schobinger staging or type of angiographic morphology.In future studies,a large number of patients should be investigated to confirm the efficacy of and indications for this treatment.

This study has some limitations.First,only 10 children were included in the study.Second,a longer follow-up period is needed to determine the eventual treatment outcomes.Finally,the evaluation approach used in this study was mostly obtained from other publications[3,15-19,21,27],in most of which the approaches were not sufficiently precise to enable a fair evaluation.

CONCLUSIONS

The management of AVMs is challenging,particularly in children.An intralesional interstitial injection of bleomycin is a feasible approach for the treatment of AVMs in children and provides safe and effective outcomes.Based on this pilot study,the need for surgical excision,particularly in the head and neck region,may be prevented,and the approach also has fewer serious complications than ethanol embolization.

FUNDING

This study was supported by the Multi-Center Clinical Research Program (DLY201613) of Shanghai Ninth People’s Hospital.

ETHICS DECLARATIONS

Ethics Approval and Consent to Participate

This study received ethical approval from the Ethics Committee of the Shanghai Ninth People’s Hospital (ID:SH9H-2014-2).All participants provided written informed consent before study enrolment.

Consent for Publication

All the authors have consented to the publication of this article.

Competing Interests

The authors declare no conflicts of interest.The authors state that the views expressed in the article are their own and not the official position of the institution or funder.