Erythematous patches in a female teenager: a novel mutation of RASA1 in capillary malformation-arteriovenous malformation syndrome type 1

The heterogeneous syndromes caused by germline mutations in genes belonging to the RAS/mitogen-activated protein kinase pathway are often referred to as RASopathies. Abnormal activation of this pathway plays a key role in the development of these disorders. Pathogenic variants in RASA1 gene cause an autosomal dominant syndrome called capillary malformation-arteriovenous malformation syndrome type 1 characterized by a broad phenotypic variability, even within the same family. In this syndrome, multifocal capillary and arteriovenous malformations are mainly localized in the central nervous system and skin. Herein, we report a patient with capillary malformation-arteriovenous malformation syndrome type 1 with a novel deletion on RASA1 gene. As this syndrome has been described just over two decades ago, it is most likely underdiagnosed. These kinds of skin lesions, even if unremarkable, should be evaluated by an experienced dermatologist.