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We report two cases with localized vascular malformations clinically resembling the "dominant lesion" seen in capillary malformation-arteriovenous malformation (CM-AVM) syndrome, however, lacking germline RASA1 variants but presenting double somatic RASA1 variants in affected tissue. Both patients presented with localized and superficial high-flow vascular malformations were treated with surgery and laser therapy and showed partial resolution. The study underscores the rarity of somatic RASA1 variants, contributes to understanding the "second-hit" pathophysiology in vascular lesions, and emphasizes the significance of clinical distinctions and genotyping for accurate diagnoses, offering implications for diagnosis, prognosis, and genetic counseling.

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BACKGROUND: Capillary malformation-arteriovenous malformation (CM-AVM) is characterized by multifocal fast-flow capillary malformations, sometimes with arteriovenous malformations/fistulas, skeletal/soft tissue overgrowth, telangiectasias, or Bier spots. Lymphatic abnormalities are infrequently reported. We describe seven patients with CM-AVM and lymphatic anomalies. METHODS: Following IRB approval, we identified patients with CM-AVM and lymphatic anomalies seen at the Vascular Anomalies Center at Boston Children's Hospital from 2003 to 2023. We retrospectively reviewed records for clinical, genetic, laboratory, and imaging findings. RESULTS: We found seven patients with CM-AVM and lymphatic abnormalities. Five patients were diagnosed prenatally: four with pleural effusions (including one suspected chylothorax) and one with ascites. Pleural effusions resolved after neonatal drainage in three patients and fetal thoracentesis in the fourth; however, fluid rapidly reaccumulated in this fetus causing hydrops. Ascites resolved after neonatal paracentesis, recurred at 2 months, and spontaneously resolved at 5 years; magnetic resonance lymphangiography for recurrence at age 19 years suggested a central conducting lymphatic anomaly (CCLA), and at age 20 years a right spermatic cord/scrotal lymphatic malformation (LM) was detected. Chylous pericardial effusion presented in a sixth patient at 2 months and disappeared after pericardiocentesis. A seventh patient was diagnosed with a left lower extremity LM at 16 months. Six patients underwent genetic testing, and all had RASA1 mutation. RASA1 variant was novel in three patients (c.1495delinsCTACC, c.434_451delinsA, c.2648del), previously reported in two (c.2603+1G>A, c.475_476del), and unavailable in another. Median follow-up age was 5.8 years (4 months-20 years). CONCLUSION: CM-AVM may be associated with lymphatic anomalies, including pericardial/pleural effusions, ascites, CCLA, and LM.

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Pathogenic variants in RASA1 are typically associated with a clinical condition called "capillary malformation-arteriovenous malformation" (CM-AVM) syndrome, an autosomal dominant genetic disease characterized by a broad phenotypic variability, even within families. In CM-AVM syndrome, multifocal capillary and arteriovenous malformations are mainly localized in the central nervous system, spine and skin. Although CM-AVM syndrome has been widely described in the literature, only 21 cases with prenatal onset of clinical features have been reported thus far. Here, we report four pediatric cases of molecularly confirmed CM-AVM syndrome which manifested during the prenatal period. Polyhydramnios, non-immune hydrops fetalis and chylothorax are only a few possible aspects of this condition, but a correct interpretation of these prenatal signs is essential due to the possible fatal consequences of unrecognized encephalic and thoracoabdominal deep vascular malformations in newborns and in family members carrying the same RASA1 variant.

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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.

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We describe a 17-year-old boy with capillary malformation-arteriovenous malformation syndrome and a massive vascular malformation of the right chest wall, shoulder, and upper arm. Persistent growth of the malformation caused cutaneous ulcerations and recurrent massive bleeding episodes. We proceeded with a modified shoulder disarticulation preceded by ligation of the subclavian artery and innominate vein by median sternotomy. After a staged debulking resection of the residual chest wall arteriovenous malformation with rotational transverse rectus abdominis myocutaneous flap coverage, the patient was discharged home safely. This report demonstrates that a multidisciplinary approach is critical for management of life-threatening complications in capillary malformation-arteriovenous malformation patients.

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BACKGROUND: High-flow vascular stains (HFVS) are lesions that have the appearance of capillary malformations/port wine stains but are associated with increased arterial flow. OBJECTIVE: To identify features of HFVS that differentiate them from typical "slow-flow" port wine stains. METHODS: Retrospective multicenter cohort study of HFVS evaluated across 7 centers was conducted. HFVS were characterized by clinical features (warmth, thrill, rapid capillary refill), radiologic findings (fast flow), or mutations associated with capillary malformation-arteriovenous malformation syndrome. Investigators reviewed photographs. RESULTS: The study reviewed 70 patients with HFVS (47 multifocal and 23 solitary). Most were flat (77%), warm to the touch (60%), and red or pink-red in color (35%), with heterogeneous color saturation (73%) and well-defined borders (71%). Regional soft tissue swelling/overgrowth was common (47%). Head and neck location was most common (38%). Among 34 HFVS with photographic review over time, all demonstrated changes in appearance. LIMITATIONS: Retrospective design, recall bias, lack of standardized time points or visual analog scale, and image variability. CONCLUSION: Heterogeneity of stain color saturation, warmth to touch, peripheral pallor, and overgrowth/soft tissue swelling help distinguish HFVS from port wine stains. Darkening of color and increased border demarcation may develop over time. These findings raise suspicion for HFVS and provide an indication to assess for extracutaneous involvement.

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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.

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Vein of Galen malformations (VOGMs) are rare developmental cerebrovascular lesions characterized by fistulas between the choroidal circulation and the median prosencephalic vein. Although the treatment of VOGMs has greatly benefited from advances in endovascular therapy, including technical innovation in interventional neuroradiology, many patients are recalcitrant to procedural intervention or lack accessibility to specialized care centers, highlighting the need for improved screening, diagnostics, and therapeutics. A fundamental obstacle to identifying novel targets is the limited understanding of VOGM molecular pathophysiology, including its human genetics, and the lack of an adequate VOGM animal model. Herein, the known human mutations associated with VOGMs are reviewed to provide a framework for future gene discovery. Gene mutations have been identified in 2 Mendelian syndromes of which VOGM is an infrequent but associated phenotype: capillary malformation-arteriovenous malformation syndrome ( RASA1) and hereditary hemorrhagic telangiectasia ( ENG and ACVRL1). However, these mutations probably represent only a small fraction of all VOGM cases. Traditional genetic approaches have been limited in their ability to identify additional causative genes for VOGM because kindreds are rare, limited in patient number, and/or seem to have sporadic inheritance patterns, attributable in part to incomplete penetrance and phenotypic variability. The authors hypothesize that the apparent sporadic occurrence of VOGM may frequently be attributable to de novo mutation or incomplete penetrance of rare transmitted variants. Collaboration among treating physicians, patients' families, and investigators using next-generation sequencing could lead to the discovery of novel genes for VOGM. This could improve the understanding of normal vascular biology, elucidate the pathogenesis of VOGM and possibly other more common arteriovenous malformation subtypes, and pave the way for advances in the diagnosis and treatment of patients with VOGM.

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RASA1 mutations have been shown to cause capillary malformation-arteriovenous malformation (CM-AVM). We describe a patient with CM-AVM and a fetus who presented with non-immune hydrops fetalis during the pregnancy. Sequencing revealed a novel RASA1 mutation in the RASGAP domain that results in a loss of function of p120-RasGap. This report expands our current genetic and clinical understanding of CM-AVM in pregnancy.

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Mutations in gene RASA1 have been historically associated with capillary malformation-arteriovenous malformation, but sporadic reports of lymphatic involvement have yet to be investigated in detail. To investigate the impact of RASA1 mutations in the lymphatic system, we performed investigational near-infrared fluorescence lymphatic imaging and confirmatory radiographic lymphangiography in a Parkes-Weber syndrome (PKWS) patient with suspected RASA1 mutations and correlated the lymphatic abnormalities against that imaged in an inducible Rasa1 knockout mouse. Whole-exome sequencing (WES) analysis and validation by Sanger sequencing of DNA from the patient and unaffected biological parents enabled us to identify an early-frameshift deletion in RASA1 that was shared with the father, who possessed a capillary stain but otherwise no overt disease phenotype. Abnormal lymphatic vasculature was imaged in both affected and unaffected legs of the PKWS subject that transported injected indocyanine green dye to the inguinal lymph node and drained atypically into the abdomen and into dermal lymphocele-like vesicles on the groin. Dermal lymphatic hyperplasia and dilated vessels were observed in Rasa1-deficient mice, with subsequent development of chylous ascites. WES analyses did not identify potential gene modifiers that could explain the variability of penetrance between father and son. Nonetheless, we conclude that the RASA1 mutation is responsible for the aberrant lymphatic architecture and functional abnormalities, as visualized in the PKWS subject and in the animal model. Our unique method to combine investigatory near-infrared fluorescence lymphatic imaging and WES for accurate phenoptyping and unbiased genotyping allows the study of molecular mechanisms of lymphatic involvement of hemovascular disorders.

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El síndrome de malformaciones capilares-malformaciones arteriovenosas (CM-AVM) es una entidad descripta recientemente, que se caracteriza por la asociación de malformaciones capilares con malformaciones arteriales o fístulas arteriovenosas. Es de herencia autosómica dominante y se produce por mutaciones en el gen RASA1. Las malformaciones capilares en este síndrome presentan ciertas características particulares por lo que son llamadas atípicas. Algunas son congénitas y otras aparecen en forma progresiva. Presentan tamaño variable (desde lesiones puntiformes hasta de varios cm de diámetro), son rosadas o amarronadas, tienen aumento de temperatura local y están rodeadas por un halo pálido. En ocasiones comprometen mucosa oral. Es importante que el dermatólogo sea capaz de reconocer este síndrome, ya que en ocasiones puede asociarse con compromiso interno.

Capillary malformation-arteriovenous malformation is a recently described disorder, characterized by the association of capillary malformations with arterial malformation or arteriovenous fistulae. It is an autosomal dominant disease caused by mutations in RASA1. Capillary malformations in this syndrome are called atypical because they share some particular characteristics. Some are congenital and others appear progressively. They varied in size (from pinpoint lesions to several centimeters of diameter), are pink or brown, sometimes warmer than normal skin and are surrounded by a pale halo. Oral mucosa can be affected. It is important for the dermatologist to recognize this syndrome, taking in account that it can be associated to internal compromise.

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