Sclerotherapy for Venous Malformations of Head and Neck: Systematic Review and Meta-Analysis

New Insights into Cervicofacial Vascular Anomalies

Congenital cervicofacial vascular anomalies are extremely rare and present many difficulties in diagnosis and treatment requiring a multidisciplinary approach. Firstly, there is little consensus on this subject among head and neck specialists. There are two main types of vascular anomalies: vascular tumors and vascular malformations. Vascular malformations are also divided into malformations with slow blood flow (veins, lymphatics, capillaries or combined) and malformations with a fast blood flow (arteriovenous malformations and fistula). Vascular tumors like hemangiomas are known for their spontaneous involution with aging, while vascular malformations grow in dimensions with age. It is very important to choose the correct differential diagnosis between cervicofacial hemangiomas and vascular malformations for proper therapy management. Anamnesis and clinical exams help in raising suspicions about the real nature of a cervico-vascular anomaly. Furthermore, imaging brings in-depth details of the anomaly, ranging from ultrasound and contrast CT to MRI scanning and minimally invasive angiography. Angiography with selective embolization is rarely a curative procedure for arteriovenous malformations, being more suitable as a preliminary step before attempted surgical removal. Surgery is clearly necessary when there are aesthetic and functional deficits. Slow-flow vascular malformations present a reduced morbidity, and in cases without involution, the surgical ablation is reserved for the cases with aesthetic dysfunctions or psychological trauma. Lymphatic malformations must undergo surgical ablation when they are associated with mass effects and compression of great vessels or aerial viscera. The prognosis after surgical removal is good, with a low rate of recurrence or morbidity. Fast-flow vascular malformations require a combined approach, with embolization and excision in the next 48 h for safety reasons. Removal may be followed by reconstructive surgery depending on the location and dimensions of the malformation, with a possible secondary recovery of the normal microscopic vessels. Some of the masses may hinder the normal airflow and swallowing. Pathology is the gold standard for confirming the clinical and imaging diagnosis.

Interdisciplinary Management of Vascular Anomalies in the Head and Neck

Vascular anomalies in the head and neck area are usually rare diseases and pose a particular diagnostic and therapeutic challenge. They are divided into vascular tumours and vascular malformations. A distinction is made between benign tumours, such as infantile haemangioma, and rare malignant tumours, such as angiosarcoma. Vascular malformations are categorised as simple malformations, mixed malformations, large vessel anomalies and those associated with other anomalies. Treatment is interdisciplinary and various modalities are available. These include clinical observation, sclerotherapy, embolisation, ablative and coagulating procedures, surgical resection and systemic drug therapy. Treatment is challenging, as vascular anomalies in the head and neck region practically always affect function and aesthetics. A better understanding of the genetic and molecular biological basis of vascular anomalies has recently led to clinical research into targeted drug therapies. This article provides an up-to-date overview of the diagnosis, clinic and treatment of vascular anomalies in the head and neck region.

Intralesional injection of bleomycin in the management of low flow vascular malformations: Results and factors affecting the outcome

OBJECTIVE

Ethanol has been a commonly used sclerosant for low-flow vascular malformations, but it carries a high risk of complications. Bleomycin has been recently introduced as a potentially effective treatment. The aim of this study was to evaluate the safety and efficacy of bleomycin intralesional injection for the treatment of low-flow vascular malformations and determine the different factors affecting the outcome.

PATIENTS AND METHODS

A total of fifty patients with low-flow vascular malformations were enrolled in the study between April 2020 and March 2022. All patients underwent preoperative duplex ultrasound and magnetic resonance angiography. The procedure was performed under ultrasound and fluoroscopic guidance. All patients were assessed for the objective improvement, ultrasound assessment, and patient-reported outcome.

RESULTS

The overall rate of objective improvement was 79.53% (78.05% in venous and 87.5% in lymphatic malformations), whereas 81.25% of the patients showed a degree of size reduction or complete obliteration on postoperative ultrasound. The patient-reported outcome analysis showed a statistically significant improvement in the mean score for the pain, overall symptoms, and self-confidence. On regression analysis, the only factor associated with poor objective outcome was diffuse lesions (ill-defined or extending in more than one body region or one compartment). No major complications were recorded.

CONCLUSIONS

Bleomycin intralesional injection is a safe and effective treatment for low-flow vascular malformations.

International Consensus Statement on Allergy and Rhinology: Sinonasal Tumors

BACKGROUND

Sinonasal neoplasms, whether benign and malignant, pose a significant challenge to clinicians and represent a model area for multidisciplinary collaboration in order to optimize patient care. The International Consensus Statement on Allergy and Rhinology: Sinonasal Tumors (ICSNT) aims to summarize the best available evidence and presents 48 thematic and histopathology-based topics spanning the field.

METHODS

In accordance with prior International Consensus Statement on Allergy and Rhinology documents, ICSNT assigned each topic as an Evidence-Based Review with Recommendations, Evidence-Based Review, and Literature Review based on the level of evidence. An international group of multidisciplinary author teams were assembled for the topic reviews using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses format, and completed sections underwent a thorough and iterative consensus-building process. The final document underwent rigorous synthesis and review prior to publication.

RESULTS

The ICSNT document consists of four major sections: general principles, benign neoplasms and lesions, malignant neoplasms, and quality of life and surveillance. It covers 48 conceptual and/or histopathology-based topics relevant to sinonasal neoplasms and masses. Topics with a high level of evidence provided specific recommendations, while other areas summarized the current state of evidence. A final section highlights research opportunities and future directions, contributing to advancing knowledge and community intervention.

CONCLUSION

As an embodiment of the multidisciplinary and collaborative model of care in sinonasal neoplasms and masses, ICSNT was designed as a comprehensive, international, and multidisciplinary collaborative endeavor. Its primary objective is to summarize the existing evidence in the field of sinonasal neoplasms and masses.

Indications, Options, and Updates on Embolic Agents

Interventional approaches to head and neck vascular anomalies have evolved with our understanding of disease pathologic condition and advances in medical and surgical treatment. Embolization's role in the disease management ranges from stand-alone treatment with curative intent to adjunctive or even palliative, depending on the lesion. This decision is best made through multidisciplinary collaboration among surgeons, interventionalists, and medical specialists. Finally, setting realistic expectations with the patient and family is a crucial step preceding any intervention. This article elaborates on the considerations influencing a given treatment plan and specific interventional strategy.

Lymphatic Leakage in Pediatric Heart Transplantation: Early Recognition and Timely Management with Interventional Radiologic and Endoscopic Therapy

Protein-losing enteropathy (PLE) is a severe complication of the Fontan procedure that leads to systemic complications owing to enteric protein loss. Hepatoduodenal lymphatic leakage resulting from increased lymphatic pressure is one such complication. We present the case of a pediatric heart transplant patient who experienced refractory PLE symptoms requiring serial albumin infusions and exhibited lymphatic leakage into the duodenum. Using diagnostic lymphangiography and endoscopy, we identified the affected area and treated it successfully with endoscopic sclerotherapy using ethanolamine injection. This treatment allowed for the cessation of lymphatic fluid and may serve as a potential intervention for PLE-associated hepatoduodenal lymphatic leakage. The present case highlights the importance of early recognition and timely intervention with radiology and endoscopic therapy to manage PLE and its associated complications.

A Clinical Study of Histopathological and Clinical Image Changes After Sclerotherapy of Lip Venous Malformations

Venous malformations (VMs) are histopathologically benign but can greatly impair patients' quality of life. Screlothprapy is known to be effective in improving symptoms without a scar, but surgical resection of residual lesions is sometimes necessary due to inadequate reduction. However, there is no consensus on what criteria should be used to consider switching to surgical treatment, and individualized decisions must be made for each case. To investigate the factors that contribute to the lack of efficacy of sclerotherapy in reducing lesions and how to predict this, the authors performed a retrospective clinical imaging and histopathological study of 6 cases of labial vein malformations treated with sclerotherapy and 3 cases without sclerotherapy. Clinical image investigations are based on magnetic resonance imaging before and after sclerotherapy. The authors found a significant decrease in the percentage of cystic components in the total lesion of VMs after sclerotherapy. Histopathological investigations are based on resected VMs with or without sclerotherapy. Elastica van Gieson stains suggested a significant increase in fibrotic tissue inside VMs treated with sclerotherapy compared with those without. In conclusion, magnetic resonance imaging signal changes inside the VMs after sclerotherapy was observed, and it may reflect fibrosis of the tissue. These changes in the VMs after sclerotherapy may reduce the effect of sclerotherapy on tissue reduction should be considered.

Clinical phenotype of adolescent and adult patients with extracranial vascular malformation

OBJECTIVE

In recent years, genotypic characterization of congenital vascular malformations (CVMs) has gained attention; however, the spectrum of clinical phenotype remains difficult to attribute to a genetic cause and is rarely described in the adult population. The aim of this study is to describe a consecutive series of adolescent and adult patients in a tertiary center, where a multimodal phenotypic approach was used for diagnosis.

METHODS

We analyzed clinical findings, imaging, and laboratory results at initial presentation, and set a diagnosis according to the International Society for the Study of Vascular Anomalies (ISSVA) classification for all consecutively registered patients older than 14 years of age who were referred to the Center for Vascular Malformations at the University Hospital of Bern between 2008 and 2021.

RESULTS

A total of 457 patients were included for analysis (mean age, 35 years; females, 56%). Simple CVMs were the most common (n = 361; 79%), followed by CVMs associated with other anomalies (n = 70; 15%), and combined CVMs (n = 26; 6%). Venous malformations (n = 238) were the most common CVMs overall (52%), and the most common simple CVMs (66%). Pain was the most frequently reported symptom in all patients (simple, combined, and vascular malformation with other anomalies). Pain intensity was more pronounced in simple venous and arteriovenous malformations. Clinical problems were related to the type of CVM diagnosed, with bleeding and skin ulceration in arteriovenous malformations, localized intravascular coagulopathy in venous malformations, and infectious complications in lymphatic malformations. Limb length difference occurred more often in patients with CVMs associated with other anomalies as compared with simple or combined CVM (22.9 vs 2.3%; P < .001). Soft tissue overgrowth was seen in one-quarter of all patients independent of the ISSVA group.

CONCLUSIONS

In our adult and adolescent population with peripheral vascular malformations, simple venous malformations predominated, with pain as the most common clinical symptom. In one-quarter of cases, patients with vascular malformations presented with associated anomalies on tissue growth. The differentiation of clinical presentation with or without accompanying growth abnormalities need to be added to the ISSVA classification. Phenotypic characterization considering vascular and non-vascular features remains the cornerstone of diagnosis in adult as well as pediatric patients.

Bleomycin electrosclerotherapy (BEST) for the treatment of vascular malformations. An International Network for Sharing Practices on Electrochemotherapy (InspECT) study group report

BACKGROUND

Biomedical applications of electroporation are expanding out of the field of oncology into vaccination, treatment of arrhythmias and now in the treatment of vascular malformations. Bleomycin is a widely used sclerosing agent in the treatment of various vascular malformations. The application of electric pulses in addition to bleomycin enhances the effectiveness of the drug, as demonstrated by electrochemotherapy, which utilizes bleomycin in the treatment of tumors. The same principle is used in bleomycin electrosclerotherapy (BEST). The approach seems to be effective in the treatment of low-flow (venous and lymphatic) and, potentially, even high-flow (arteriovenous) malformations. Although there are only a few published reports to date, the surgical community is interested, and an increasing number of centers are applying BEST in the treatment of vascular malformations. Within the International Network for Sharing Practices on Electrochemotherapy (InspECT) consortium, a dedicated working group has been constituted to develop standard operating procedures for BEST and foster clinical trials.

CONCLUSIONS

By treatment standardization and successful completion of clinical trials demonstrating the effectiveness and safety of the approach, higher quality data and better clinical outcomes may be achieved.

A systematic review and network meta-analysis of the effectiveness of sclerotherapy for venous malformation

OBJECTIVE

Sclerotherapy for venous malformation has been widely used; however, no guidelines are available to assess the effectiveness of different sclerotherapy agents. We conducted a systematic review and network meta-analysis to investigate the effectiveness of sclerotherapy agents for venous malformations.

METHODS

Three electronic databases were searched from their inception (1950) to April 29, 2021. Studies comparing the effectiveness of different sclerotherapy agents were included. The risk of bias within and across studies was assessed. Pairwise meta-analyses were conducted, followed by a network meta-analysis. We also assessed inconsistency and publishing bias using various approaches.

RESULTS

Seven studies with 547 patients in six arms were included in the present study. We defined the response and complete response as two separate outcomes. Significant differences were observed in four comparisons with respect to the response (ethanol vs bleomycin, ethanol vs polidocanol, ethanol vs sodium tetradecyl sulfate, polidocanol vs sodium tetradecyl sulfate). No statistically significant differences were found in the other comparisons. The evidence network revealed that for the response outcome, ethanol ranked first, followed by pingyangmycin, polidocanol, sodium morrhuate, bleomycin, and, finally, sodium tetradecyl sulfate. For the complete response outcome, pingyangmycin had the best results, followed by sodium morrhuate, polidocanol, ethanol, bleomycin, and, finally, sodium tetradecyl sulfate. Major complications, such as facial nerve palsy, serious local swelling, and necrosis, had occurred mostly in the ethanol group and rarely in the other groups. Because of the limited data, no further analysis of major complications was conducted. Our confidence in the comparisons and rankings was low. We found no verified inconsistency or publishing bias in the present study using the existing approaches.

CONCLUSIONS

Ethanol showed a significantly better response statistically compared with the other agents. However, ethanol had also resulted in the highest incidence of complications. Pingyangmycin showed the second-best response, best complete response, and a low rate of complications, respectively. Overall, pingyangmycin achieved excellent performance and balance in terms of the different outcomes. However, they could not be adequately recommended from the available data. More superior trials, especially randomized controlled trials, are needed in the future.

Multicentered analysis of percutaneous sclerotherapies in venous malformations of the face

Objectives

To evaluate the safety and outcome of image-guided sclerotherapy for treating venous malformations (VMs) of the face.

Materials and methods

A multicenter cohort of 68 patients with VMs primarily affecting the face was retrospectively investigated. In total, 142 image-guided sclerotherapies were performed using gelified ethanol and/or polidocanol. Clinical and imaging findings were assessed to evaluate clinical response, lesion size reduction, and complication rates. Sub-analyses of complication rates depending on type and injected volume of the sclerosant as well as of pediatric versus adult patient groups were conducted.

Results

Mean number of procedures per patient was 2.1 (±1.7) and mean follow-up consisted of 8.7 months (±6.8 months). Clinical response (n = 58) revealed a partial relief of symptoms in 70.7% (41/58), 13/58 patients (22.4%) presented symptom-free while only 4/58 patients (6.9%) reported no improvement. Post-treatment imaging (n = 52) revealed an overall objective response rate of 86.5% (45/52). The total complication rate was 10.6% (15/142) including 4.2% (7/142) major complications, mostly (14/15, 93.3%) resolved by conservative means. In one case, a mild facial palsy persisted over time. The complication rate in the gelified ethanol subgroup was significantly higher compared to polidocanol and to the combination of both sclerosants (23.5 vs. 6.0 vs. 8.3%, p = 0.01). No significant differences in complications between the pediatric and the adult subgroup were observed (12.1 vs. 9.2%, p = 0.57). Clinical response did not correlate with lesion size reduction on magnetic resonance imaging (MRI).

Conclusion

Image-guided sclerotherapy is effective for treating VMs of the face. Clinical response is not necessarily associated with size reduction on imaging. Despite the complex anatomy of this location, the procedures are safe for both adults and children.

Intravascular Endothelial Hyperplasia of the Foot: A Case Series

Intravascular endothelial hyperplasia is a benign soft tissue mass rarely reported in the foot. Advanced imaging and confirming a benign diagnosis are critical for any soft tissue mass. This paper identifies 2 patients that developed intravascular endothelial hyperplasia tumors which required surgical excision. A 17-year-old male patient presented to clinic complaining of a painful bump to the arch of his right foot which he related to an injury 9 months prior. Magnetic resonance imaging of the right foot revealed a mass within the plantar subcutaneous fat that was serpiginous in nature similar to adjacent branching vessels favoring a low-flow vascular malformation. A 38-year-old female with Multiple Sclerosis presented with complaints of persistent symptoms of pain to the 1^st interspace, difficult ambulation and neuritis. Ultrasound and MRI observed solid, multilobulated mass, with internal vascular malformation, MRI describing intrinsic involvement along the abductor musculature and flexor tendons. Both lesions were surgically excised and sent for pathology. Pathology report indicated a diagnosis of intravascular papillary endothelial hyperplasia or Masson's tumor in both cases. Pathology diagnosis of intravascular papillary endothelial hyperplasia is generally good with wide resection leading to low recurrence rates. Both patients in the current study have progressed postoperatively with resolution of symptoms and without recurrence.

Rare Neurovascular Diseases in Korea: Classification and Related Genetic Variants

Rare neurovascular diseases (RNVDs) have not been well-recognized in Korea. They involve the central nervous system and greatly affect the patients' lives. However, these diseases are difficult to diagnose and treat due to their rarity and incurability. We established a list of RNVDs by referring to the previous literature and databases worldwide to better understand the diseases and their current management status. We categorized 68 RNVDs based on their pathophysiology and clinical manifestations and estimated the prevalence of each disease in Korea. Recent advances in genetic, molecular, and developmental research have enabled further understanding of these RNVDs. Herein, we review each disease, while considering its classification based on updated pathologic mechanisms, and discuss the management status of RNVD in Korea.

Sclerotherapy with polidocanol microfoam in head and neck venous and lymphatic malformations

Objective

Polidocanol sclerotherapy of head and neck venous malformations (VMs) and lymphatic malformations (LMs) has been reported only in limited series. In this manuscript we evaluated the efficacy and safety of polidocanol sclerotherapy in a series of head and neck venous and lymphatic malformations.

Methods

This retrospective observational study analysed data on 20 head and neck VMs and LMs that underwent to percutaneous or endoscopic intra-lesional 3% polidocanol microfoam sclerotherapy at our institution. Clinical response was ranked as excellent, moderate and poor based on volume reduction by MRI and resolution of symptoms.

Results

The median volume decreased from 19.3 mL to 5.8 mL after sclerotherapy (mean volume reduction: 72.98 ± 16.1%). An excellent-moderate response was observed in 94.4% of cases. We observed a mean volume reduction of 79.5 ± 16.1 in macrocystic LMs, of 76.1 ± 13.0% in VMs, of 60.5 ± 10.9% in mixed lymphatic ones and 42.5% in microcystic lymphatic ones.

Conclusions

Polidocanol sclerotherapy appears to be an effective and safe treatment for venous and lymphatic head and neck malformations. We observed the best responses in macrocystic LMs and VMs, whereas mixed lymphatic ones showed a moderate response and microcystic lymphatic ones a poor response.

Clinical evaluation and animal experimental study of different mass concentrations of pingyangmycin in the local injection treatment of lip venous malformation

Background

This study investigated the clinical efficacy of different mass concentrations of pingyangmycin in the local injection treatment of lip venous malformation. An animal experimental study of the histopathological effects of different mass concentrations of pingyangmycin on the normal lip tissue of rabbits was also conducted.

Methods

(I) We retrospectively analysed 98 out-patients with lip venous malformation in the Stomatological Hospital and the Fourth Affiliated Hospital of China Medical University from January 2008 to June 2013. The 98 cases were treated by local injection of different mass concentrations (8 mg/3 mL and 8 mg/5 mL) of pingyangmycin for the different sites of the lips. The clinical efficacy was observed, and adverse reactions were recorded. (II) 60 healthy male rabbits were randomly divided into three groups: a 8 mg/5 mL pingyangmycin group, a 8 mg/3 mL pingyangmycin group, and a control group. The right upper lips of the experimental groups were injected with 1ml pingyangmycin (8 mg/5 mL) and 1ml pingyangmycin (8 mg/3 mL) respectively, and the control group was injected with the same volume of normal saline. The thickness of the right upper lip of rabbits in the experimental groups and the control group was measured on the 21st, 28th, 35th, and 60th days after the first injection. Histopathological changes at the injection site were observed by light microscope and transmission electron microscope.

Results

Venous malformations involving the skin tissues of the lips (pingyangmycin 8 mg/3 mL) had an effective rate of 93.62%, and those involving the labial mucosa tissues (pingyangmycin 8 mg/5 mL) had an effective rate of 98.04%. In the animal experiment, there were statistically significant differences in the thickness of the injection site among the 8 mg/3 mL group, 8 mg/5 mL group, and the control group at different time points (P<0.01).

Conclusions

The local injection of pingyangmycin in the treatment of lip venous malformations was efficient, safe and reliable. In the process of clinical application, attention should be paid when the concentration is 8 mg/3 mL to avoid local tissue atrophy and other complications.

Vascular anomalies: Classification and management

Vascular anomalies are broadly classified into two major categories: vascular tumors and vascular malformations. Most vascular anomalies are caused by sporadic mosaic gene mutations, and recent genetic studies have advanced our understanding of the molecular pathways involved in their pathogenesis. These findings have suggested new therapeutic approaches to vascular anomalies, focusing on their pathogenetic mechanism. This chapter seeks to integrate an improved molecular understanding within the updated classification system of the International Society for Study of Vascular Anomalies. We emphasize the genetic, radiologic, and interventional aspects of diagnosis and management in hopes of allowing improved multidisciplinary collaboration surrounding these complex and interesting anomalies.

Utilizing immediate preoperative n-BCA in the resection of head and neck venous and lymphatic malformations

PURPOSE/OBJECTIVE

To add to the current literature on single stage excision of head and neck vascular malformations with preoperative n-butyl cyanoacrylate (n-BCA) glue. Unlike previous studies, this series includes pediatric and adult patients, highlights a single stage partial excision of a complex venous malformation, and describes the first description of using glue prior to resection of a macrocystic lymphatic malformation.

STUDY DESIGN

Case series with chart review.

SETTING

Tertiary-care adult and pediatric hospital.

SUBJECTS AND RESULTS

Four patients (3 males - 9, 13, 25 years, 1 female - 61 years) underwent same day excision of head and neck vascular malformations utilizing immediate preoperative n-BCA glue embolization performed by interventional radiology and otolaryngology, as described by Tieu et al. The indications for resection included bleeding (1/4), pain (3/4), cosmetic deformity (3/4), and discomfort with denture wear (1/4). Prior interventions included none (1/4), cautery and primary closure to control acute hemorrhage (1/4), and sclerotherapy (2/4). Treatments included complete embolization and resection of simple venous malformation (VM)s of the oral cavity/lip (2/4), partial embolization and resection of a complex hemifacial venous malformation (VM) (1/4), and complete embolization and resection of a lymphatic malformation (LM) (1/4). On average, 97 min of anesthesia time was added for the preoperative embolization procedure (range, 94-104 min). All patients had a successful embolization without need for coils. Operative time ranged from 28 to 44 min for the simple cases and was 6 h and 30 min for the complex case. There was minimal blood loss in all cases. There were no associated complications, lesion recurrences, or long-term deficits at an average follow-up of 5 months. The patient with the complex hemifacial VM demonstrated subtle lower facial weakness post-operatively, which completely resolved within two months.

CONCLUSIONS

Treatment of head and neck vascular malformations with preoperative n-BCA glue and subsequent surgical excision is a viable method for both simple and complex lesions. The safety and efficacy of this technique has been demonstrated in the past in a limited number of studies. This study further supports the use of this technique to address patient concerns such as pain or discomfort and cosmetic deformity, even if the lesion is only partially resectable. In our series a lymphatic malformation refractory to sclerotherapy was treated with a similar technique of glue and resection, following aspiration of the mucoid LM fluid. Our series emphasizes that pediatric vascular malformations carry functional and cosmetic deficits into adulthood that can and should be addressed in this patient population. Therefore, same-day embolization and resection should be coordinated when possible, in order to optimize patient safety and convenience.

Sclerotherapy of Vascular Malformations in the Oral Cavity-Minimizing Postoperative Morbidity

Vascular malformations (VMs) are a wide vascular or lymphatic group of lesions common on the head and neck. The objective of this study was to assess the efficacy and morbidity of sclerotherapy for the treatment of VMs in the oral and perioral area. Special attention was given to factors that may contribute to minimizing postoperative morbidity. Data from 25 patients (32 lesions) with oral VMs submitted to sclerotherapy with monoethanolamine oleate (EAO) were included. A structured form was used to collect data. An arbitrary score was determined to evaluate postoperative morbidity. Each of the following signs or symptoms received one point: pain, swelling, hematoma, ulceration, erythema, transient numbness, and transient itching. Pain and swelling were further divided into mild to moderate (1 point) and severe (2 points). Theoretically, the score was in the range of 0–9. Calculated scores ranged 0–4. The patients were further divided into two groups with scores of 0–1 denoting minimal morbidity (MIN) and 2–4 denoting significant morbidity (SIG). The number of lesions in each morbidity-score group were comparable (MIN 17and SIG 15). There were no statistically significant differences between the groups regarding age, number of applications, or average injection volume per mm lesion. Statistically significant differences were noted regarding gender (p = 0.05), lesion diameter (p = 0.030), total volume of first (p = 0.007) and second application (p = 0.05), and total injected volume (p = 0.03). Factors contributing to the risk for significant morbidity included being male, lesion diameter > 5 mm, volume > 0.3 mL per application, and total injected volume > 0.3 mL. A waiting time of 12 weeks prior to additional EAO application was required in 12 out of 29 lesions for clinical observation of complete regression. It was concluded that sclerotherapy with EAO as monotherapy is easy to apply, safe, and effective within a small number of sessions. Application of <0.3 mL EAO per session, and a waiting time of 12 weeks prior to the second application, would significantly minimize morbidity.