RASopathies: Dermatologists’ viewpoints

Ras/mitogen-activated protein kinase pathway dysregulation results in a group of disorders, collectively termed as RASopathies. Neurofibromatosis type 1, Noonan syndrome, Noonan syndrome with multiple lentigines, Noonan syndrome/loose anagen hair, Legius syndrome, Costello syndrome, cardio-facio-cutaneous syndrome and capillary malformation-arteriovenous malformation are the well- recognized RASopathies. These are characterized by multi-organ tumours and hamartomas. Some other features in common are facial dysmorphism, skeletal abnormalities, congenital heart disease, neurocognitive abnormalities and risk of various solid-organ and haematological malignancies. Some of the RASopathies are heterogeneous, caused by several gene mutations resulting in variations in phenotypes and severity ranging from mild to fatal. Significant phenotypic overlaps among different disorders, often makes it difficult to pinpoint a clinical diagnosis. Specific cutaneous manifestations are present in some of the RASopathies and are often the earliest clinical signs/symptoms. Hence, dermatologists contribute significantly as primary care physicians by identifying disorder-specific cutaneous lesions. However, diagnostic work-up and management of these disorders are often multidisciplinary. Confirmation of diagnosis is possible only by genetic mapping in each case. Genetic counseling of the patients and the affected families is an important component of the management. The aim of this review is description of cutaneous manifestations of RASopathies in the background of multi-system involvement to enable dermatologists a comprehensive and logical approach to work up and diagnose such patients in the absence of facility for specific molecular testing.

A de novo truncating mutation in ASXL1 associated with segmental overgrowth

Mutations in genes involved in chromatin remodelling have been implicated in broad phenotypes of congenital abnormalities and neurodevelopment. However, limited genotype–phenotype correlations are available for some of the rarestgenetic disorders that affect chromatin regulation. We hereby describe a 12-year-old girl presented at birth with severe hypotonia, developmental delay, a mid-line capillary malformation and distinctive craniofacial features. During the natural history of her disease, the girl developed severe spasticity and drug-resistant seizures, leading to a diagnosis of Bohring–Opitz syndrome (BOS). We performed whole-exome sequencing (WES) and identified a de novo mutation in ASXL1 (c.2033dupG) which results in the introduction of a premature stop codon (p.R678fs*6). ASXL1 encodes a polycomb repressive complex protein implicated in chromatin regulation and de novo mutations are a known cause of BOS. Phenotypes with segmental craniofacial overgrowth associated to midline capillary malformations enlarge the clinical spectrum of BOS at onset and further expand the differential diagnosis in ASXL1 mutation carriers.

Current understanding of the genetics of extracranial arteriovenous malformation / 中华整形外科杂志

Arteriovenous malformation (AVM) is defined as a congenital vascular anomaly that shunts blood from arteries to veins with no capillary perfusion. In some rare hereditary diseases, including capillary malformation-arteriovenous malformation (CM-AVM), hereditary hemorrhagic telangiectasia (HHT), PTEN hamartoma-tumor syndrome (PHTS), AVM is generally considered the characteristic clinic presentation. This review primarily focused on the mechanisms of genetic regulation during embryonic vasculature development, genetic mutations in TGF-beta signaling pathway of HHT, PTEN mutations in PHTS and genetic screening of CM-AVM. In addition, current findings in somatic mutations of extracranial AVM were discussed as well. This review aimed to provide insight into the etiology to help the diagnosis and treatment of extracranial AVM in clinic.

Nevus Vascularis Mixtus / 대한피부과학회지

The concept of mosaicism has been used to explain different cutaneous patterns, such as the lines of Blaschko, the checkerboard pattern, the phylloid pattern, and a patchy pattern. Many mosaic patterns are caused by loss of heterozygosity, the genetic mechanism by which a heterozygous somatic cell becomes either homozygous or hemizygous. A particular form of loss of heterozygosity is twin spotting, which give rise to two contrary homozygous daughter cells. The concept of twin spotting has been used for some of these human phenotypes, which are characterized by the co-occurrence of two different nevi, including nevus vascularis mixtus. Nevus vascularis mixtus is a rare vascular malformation characterized by the coexistence of a nevus anemicus and a nevus telangiectaticus, and can be associated with extra-cutaneous anomalies, such as cerebral malformations. Herein, we report a 6-year-old girl with paired cutaneous vascular nevi telangiectaticus, anemicus, and nevus vascularis mixtus, that were distributed on the left side of her chest and left arm, without other systemic and neurologic anomalies.

Megalencephaly-capillary malformation-polymicrogyria syndrome: the first case report in Korea / 소아과

Megalencephaly-capillary malformation-polymicrogyria syndrome (MCAP), previously known as macrocephaly-cutis marmorata telangiectatica congenita and macrocephaly-capillary malformation syndrome, is a rare multiple-malformation syndrome that is characterized by progressive megalencephaly, capillary malformations of the midline face and body, or distal limb anomalies such as syndactyly. Herein, we report a female infant case that satisfies the recently proposed criteria of MCAP and describe the distinctive neuroradiological and morphological features. We have also reviewed recently published reports and the diagnostic criteria proposed by various authors in order to facilitate the clinical diagnosis of these children in pediatric neurology clinics.

Megalencephaly-capillary Malformation Syndrome / 대한피부과학회지

Megalencephaly-capillary malformation syndrome is a disorder characterized by megalencephaly or hemimegalencephaly, focal or generalized somatic overgrowth, and vascular malformations. Other characteristic features are neonatal hypotonia, hydrocephalus, developmental delay, syndactyly/polydactyly, frontal bossing, and connective tissue dysplasia. Previously reported patients exhibit wide phenotypic variability in clinical and neuroradiological findings. Differential diagnosis may be challenging for clinicians due to other similar neurocutaneous syndromes. Herein, we report an 11-month-old male infant that presented with extensive, diffuse, reticulated, erythematous patches on his face, trunk, and extremities. Physical examination revealed an increased head circumference (>97 percentile), frontal bossing, hypertrophy of the right arm and leg, and syndactyly on both feet. Borderline developmental delay was identified, and magnetic resonance imaging of the brain revealed an enlarged right cerebral hemisphere and non-obstructive ventriculomegaly. To our knowledge, this is the first report of megalencephalycapillary malformation syndrome in Korean literature.

Case of Surgical Treatment with Free Flap on Large Size Facial Capillary Malformation

Capillary malformation is common vascular malformation. In case of facial capillary malformation, patients' cosmetic and functional deficits are quite significant. The standard treatment which has been applied so far for capillary malformation is pulsed dye laser with 585nm. But in case of advanced capillary malformation, surgical interventions are inevitable. The problem of large size facial capillary malformation is how to cover the remnant defect, which occurs after resection. In this case, authors have experienced surgical treatment of large size facial capillary malformation and covered the large facial defect with free thoracodorsal artery perforator flap. The flap was thick, so facial asymmetry remained after the first surgery. But with the secondary procedure, authors have made more symmetric figures. The patient was satisfied with the result. Using free flap to replace the defect after resection due to capillary malformation is useful for these kinds of cases.