Histopathologic and ultrasound characteristics of cutaneous capillary malformations in a patient with capillary malformation-arteriovenous malformation syndrome

Capillary Malformation-arteriovenous Malformation Type 2: A Case Report and Review

Capillary malformation-arteriovenous malformation syndrome is a rare genodermatosis with cutaneous capillary malformations and a risk of associated fast-flow malformations. We describe here a four-generation family with a novel heterozygous pathogenic variant in the EPHB4 gene (NM_004444.5 (EPHB4): c.2224G>C, p.(Ala742Pro)). A review of the literature retrieved 127 patients with capillary malformation-arteriovenous malformation syndrome and confirmed variants in EPHB4. Multiple capillary malformations were present in 114 (89.76%) patients, and 12 (9.44%) patients had a solitary capillary malformation. Arteriovenous malformations/fistulas were present in 23 (18.1%) patients, and were located within the central nervous system in 5 (3.9%) patients. Not all papers included description of epistaxis. Telangiectasias were reported in 28 (22%) patients, and Bier spots were described in 20 (15.7%) patients. The clinical characteristics of capillary malformation-arteriovenous malformation syndrome are diverse and often discrete, which can make it difficult to distinguish capillary malformationarteriovenous malformation syndrome from hereditary haemorrhagic telangiectasia.

CM-AVM syndrome - A prospective observational study of unrelated paediatric cases

OBJECTIVE

The main objective of this study is to describe the clinical spectrum of CM-AVM syndrome as well as radiological and genetic findings.

METHODS

This is a single-centre prospective observational study performed at Sydney Children's Hospital. Patients under the age of 18 years that presented to our paediatric dermatology clinic or vascular birthmark clinic between January 2015 and September 2020 with one or more geometric shaped pink/ red/ brown macule with a peripheral pallor characteristic of a high-flow vascular stain were included. Children subsequently diagnosed with other diagnosis or family members with CM-AVM syndrome were excluded.

RESULTS

Sixty children were included, with two subsequently excluded. A third of patients (n = 22, 38%) presented with a single characteristic HFVS, whereas the remaining two thirds (n = 36; 62%) had multiple HFVS. In children with multiple HFVS, one notably larger HFVS was detected in the majority of children (n = 32, 88%). In 33 patients, a brain and spine MRI was performed, which detected a spine AVM in one symptomatic patient with sensorimotor deficits. No cerebral AVM or AVF was picked up in the cohort. A RASA 1 result was available for evaluation in 24, of which 16 (67%) were positive. An EPHB4 result was available in eight, two (25%) of which were positive.

CONCLUSIONS

One large HFVS often accompanied by multiple small HFVS can be seen in most patients. Despite of the lack of genetic confirmation of diagnosis in single lesions, this phenotype might be of interest and warrants further investigation.

Capillary Malformation-Arteriovenous Malformation Syndrome

Capillary malformation-arteriovenous malformation (CM-AVM) is an autosomal dominant inherited rare type of vascular malformation encountered in a neonate and first described in 2003. It has been reported in association with heterozygous mutations in the RASA1 gene, which encodes the protein RASp21. In 2010, a German doctor proposed rhodoid nevus as a name for this type of capillary malformation; in ancient Greek, rhodoides means “rose-like” or “rose-colored.” Accordingly, CM-AVM could also be called “rhodoid nevus syndrome.” We report this case as its very challenging diagnosis with its further differentials and its association with thrombocytopenia.

Ultrasound Evaluation of Pediatric Slow-Flow Vascular Malformations: Practical Diagnostic Reporting to Guide Interventional Management

OBJECTIVE. This article reviews the ultrasound characteristics of pediatric slow-flow vascular malformations and underscores findings that significantly impact diagnosis and treatment. Key imaging features are discussed including lesion size, malformation location, morphology, and mimics. CONCLUSION. Ultrasound findings affect the management of slow-flow vascular malformations and should be emphasized in lesion diagnosis. Superficial, focal lesions with well-defined margins are ideal for ultrasound evaluation.

Histopathological hallmarks of cutaneous lesions of capillary malformation-arteriovenous malformation syndrome

IMPORTANCE

Capillary malformation-arteriovenous malformation (CM-AVM) syndrome is a recently described syndrome with distinctive cutaneous lesions. Very little is known about the histopathology of these lesions.

OBJECTIVE

The purpose of the study was to evaluate the histopathological characteristics of the pink macules of the CM-AVM syndrome and to investigate if these pink macules could be classified as capillary malformations or arteriovenous malformations based on their histopathological features.

DESIGN-SETTINGS-PARTICIPANTS

We conducted a retrospective multicenter study involving eight hospitals in Spain. Fifteen biopsies from pink macules of the CM-AVM syndrome were analysed and compared with five biopsies of diverse capillary malformations and three stage I arteriovenous malformations.

RESULTS

Pink macules' biopsies of the CM-AVM syndrome showed similar features including a high vascular density encompassing capillaries and numerous thick-walled arterioles mainly located in the superficial dermis, a predominance of elongated over round vessels, scarce or absent erythrocytes within the lumina and discrete perivascular inflammation. CMs were characterized by an increased number of capillary-type vessels mostly rounded and located in the upper dermis. AVMs were composed by highly increased numbers of vessels with a branching pattern involving the full thickness of the dermis, without erythrocytes within the lumina. Wilms tumour 1 protein was positive in the endothelial cells both in pink macules of the CM-AVM and in arteriovenous malformations.

CONCLUSIONS AND RELEVANCE

Pink macules of the CM-AVM syndrome seem to be different from capillary malformations. Our results suggest that histologically and immunohistochemically they are closer to incipient arteriovenous malformations than to capillary malformations. A deepened knowledge about the nature of these skin lesions will contribute to the better understanding of capillary malformation-arteriovenous malformation syndrome, and will open the possibility of new and more specific treatments in the future.

Role of colour-Doppler high-frequency ultrasonography in capillary malformation-arteriovenous malformation syndrome: a case series

High-frequency ultrasonography (HFUS) represents a useful adjunct for dermatologists in the diagnosis of capillary malformation-arteriovenous malformation (CM-AVM) syndrome. We present a paediatric case series of 6 patients with confirmed RASA1 gene mutation in whom HFUS demonstrated AVM beneath cutaneous CM-like lesions greater than 1.5 cm.

Cutaneous ultrasound and its utility in Pediatric Dermatology: Part II-Developmental anomalies and vascular lesions

High-frequency ultrasonography represents a promising tool for pediatric dermatologists. It is a noninvasive and harmless diagnostic technique that is especially appealing when working with children. It can be easily performed at the patient's bedside, avoiding diagnostic delays, sedation, or multiple visits. It represents a useful adjunct to clinical examination and aids our understanding of cutaneous pathology. In this second part, we describe the ultrasonographic findings of developmental anomalies and vascular lesions.

EphrinB2-EphB4-RASA1 Signaling in Human Cerebrovascular Development and Disease

Recent whole exome sequencing studies in humans have provided novel insight into the importance of the ephrinB2-EphB4-RASA1 signaling axis in cerebrovascular development, corroborating and extending previous work in model systems. Here, we aim to review the human cerebrovascular phenotypes associated with ephrinB2-EphB4-RASA1 mutations, including those recently discovered in Vein of Galen malformation: the most common and severe brain arteriovenous malformation in neonates. We will also discuss emerging paradigms of the molecular and cellular pathophysiology of disease-causing ephrinB2-EphB4-RASA1 mutations, including the potential role of somatic mosaicism. These observations have potential diagnostic and therapeutic implications for patients with rare congenital cerebrovascular diseases and their families.

Phenotype of CM-AVM2 caused by variants in EPHB4: how much overlap with hereditary hemorrhagic telangiectasia (HHT)?

PURPOSE

EPHB4 variants were recently reported to cause capillary malformation-arteriovenous malformation 2 (CM-AVM2). CM-AVM2 mimics RASA1-related CM-AVM1 and hereditary hemorrhagic telangiectasia (HHT), as clinical features include capillary malformations (CMs), telangiectasia, and arteriovenous malformations (AVMs). Epistaxis, another clinical feature that overlaps with HHT, was reported in several cases. Based on the clinical overlap of CM-AVM2 and HHT, we hypothesized that patients considered clinically suspicious for HHT with no variant detected in an HHT gene (ENG, ACVRL1, or SMAD4) may have an EPHB4 variant.

METHODS

Exome sequencing or a next-generation sequencing panel including EPHB4 was performed on individuals with previously negative molecular genetic testing for the HHT genes and/or RASA1.

RESULTS

An EPHB4 variant was identified in ten unrelated cases. Seven cases had a pathogenic EPHB4 variant, including one with mosaicism. Three cases had an EPHB4 variant of uncertain significance. The majority had epistaxis (6/10 cases) and telangiectasia (8/10 cases), as well as CMs. Two of ten cases had a central nervous system AVM.

CONCLUSIONS

Our results emphasize the importance of considering CM-AVM2 as part of the clinical differential for HHT and other vascular malformation syndromes. Yet, these cases highlight significant differences in the cutaneous presentations of CM-AVM2 versus HHT.

Classification and ultrasound findings of vascular anomalies in pediatric age: the essential

Proper nomenclature is a major obstacle in understanding and managing vascular anomalies. Often the same term is used for totally different types of lesions or, conversely, the same lesion may be labeled with different terms. Although in recent times there has been a greater understanding of the problems concerning vascular anomalies, episodes of improper use of terminology still remain. The aim of this article, starting from the most recent classification of vascular anomalies, is to provide a clinical and instrumental approach to identifying these lesions and to converge towards a clear and unambiguous terminology that must become univocal among the various operators to avoid diagnostic misunderstandings and therapeutic errors.

Classification and Pathology of Congenital and Perinatal Vascular Anomalies of the Head and Neck

Accurate histopathologic description in correlation with clinical and radiological evaluation is required for treatment of vascular anomalies, both neoplastic and malformative. It is important to examine current clinical, histologic, and immunophenotypical features that distinguish the major types of congenital and perinatal vascular anomalies affecting the head and neck. General discussions of pathogenesis and molecular diagnosis must also be taken into account. This article provides an overview of the features that distinguish the major types of congenital and perinatal vascular anomalies affecting the head and neck, and summarizes the diagnostic histopathologic criteria and nomenclature currently applied to these lesions.

Somatic second hit mutation of RASA1 in vascular endothelial cells in capillary malformation-arteriovenous malformation

Capillary malformation-arteriovenous malformation (CM-AVM) is an autosomal dominant vascular disorder that is associated with inherited inactivating mutations of the RASA1 gene in the majority of cases. Characteristically, patients exhibit one or more focal cutaneous CM that may occur alone or together with AVM, arteriovenous fistulas or lymphatic vessel abnormalities. The focal nature and varying presentation of lesions has led to the hypothesis that somatic "second hit" inactivating mutations of RASA1 are necessary for disease development. In this study, we examined CM from four different CM-AVM patients for the presence of somatically acquired RASA1 mutations. All four patients were shown to possess inactivating heterozygous germline RASA1 mutations. In one of the patients, a somatic inactivating RASA1 mutation (c.1534C > T, p.Arg512*) was additionally identified in CM lesion tissue. The somatic RASA1 mutation was detected within endothelial cells specifically and was in trans with the germline RASA1 mutation. Together with the germline RASA1 mutation (c.2125C > T, p.Arg709*) in the same patient, the endothelial cell somatic RASA1 mutation likely contributed to lesion development. These studies provide the first clear evidence of the second hit model of CM-AVM pathogenesis.

Clinical and sonographic features of pediatric soft-tissue vascular anomalies part 2: vascular malformations

Vascular malformations are a heterogeneous group of entities, many of which present in the pediatric age group. Sonography plays a major role in the management of children with these vascular anomalies by providing information that helps in diagnosing them, in assessing lesion extent and complications, and in monitoring response to therapy. The interpretation of sonographic findings requires correlation with clinical findings, some of which can be easily obtained at the time of scanning. This has to be combined with the use of appropriate nomenclature and the most updated classification in order to categorize these patients into the appropriate management pathway. Some vascular malformations are part of combined vascular anomalies or are associated with syndromes that include other disorders, frequently limb overgrowth, and these are now being reclassified based on their underlying genetic mutation. Sonography has limitations in the evaluation of some vascular malformations and in these cases MR imaging might be considered the imaging modality of choice, particularly for lesions that are large, that involve multiple compartments or are associated with other soft-tissue and bone abnormalities. In this article, which is part 2 of a two-part series, the authors review the most relevant clinical and sonographic features of arteriovenous, capillary, venous and lymphatic malformations as well as vascular malformations that are part of more complex conditions or associated with syndromes, including Parkes-Weber syndrome, phosphatase and tensin homologue (PTEN) hamartoma tumor syndromes, Klippel-Trénaunay syndrome, CLOVES (congenital lipomatous overgrowth, vascular malformations, epidermal nevi and skeletal anomalies) syndrome, fibro-adipose vascular anomaly and Proteus syndrome.

A Typical Vascular and Pigmentary Dermoscopic Pattern of Capillary Malformations in Capillary Malformation-Arteriovenous Malformation Syndrome: Report of Four Cases

We report dermoscopic characteristics of cutaneous capillary malformations in four patients with capillary malformation-arteriovenous malformation (CM-AVM) syndrome. We observed a mixed vascular and pigmentary pattern with branched linear vessels and an underlying homogeneous brown background. Disappearance of the vascular pattern on pressure revealed an underlying faint pigmentary reticular pattern. Our results suggest that this typical biphasic pattern on dermoscopy may be useful for the diagnosis of CM-AVM syndrome.

Update on the Use of Ultrasound in Vascular Anomalies

Advances in our understanding of the biology and therapy of vascular anomalies have made this condition a common reason for consulting a dermatologist. In addition, multidisciplinary units have been created to manage patients with complex vascular anomalies. Although most vascular anomalies are diagnosed based on clinical findings, a thorough evaluation often requires additional imaging tests to determine the nature, extension, and prognosis of these lesions. Because it is fast and noninvasive, ultrasound is usually the first imaging test ordered. In the present review, we provide a state-of-the-art synthesis of key concepts in the ultrasound examination of vascular anomalies so that they are more accessible to clinicians and medical imaging specialists involved in the management of these lesions.