Atrophic skin patches with abnormal elastic fibers as a presenting sign of the MASS phenotype associated with mutation in the fibrillin 1 gene.

IMPORTANCE: Marfan syndrome (MFS) is a dominantly inherited disorder of connective tissue caused by mutations in the fibrillin 1 gene (FBN1). The most common skin finding in MFS is striae distensae. Particular individuals referred for suspected MFS who do not completely fulfill the MFS diagnostic criteria are classified as having a MASS phenotype. The acronym represents the following manifestations: a prolapsed mitral valve, myopia, aortic root enlargement, and skeletal and skin manifestations. Mutations in FBN1 have been shown to be associated in some cases with the MASS phenotype. Skin manifestations may be an important clue to the diagnosis of these disorders. OBSERVATIONS: We studied a patient referred for unusual atrophic skin patches on the buttocks. Results of histopathological examination and electron microscopy demonstrated markedly abnormal elastic fibers. Subsequent medical genetics evaluation led ultimately to the diagnosis of the MASS phenotype and the discovery of an underlying FBN1 mutation. CONCLUSIONS AND RELEVANCE: Although the clinical suspicion and diagnosis of MFS and related disorders are usually established by its main associated clinical features, including ophthalmologic, skeletal, and vascular involvement, clinicians should be aware of the associated skin manifestations, including unusual atrophic patches with abnormal elastic fibers that can sometimes be the first noted sign of the genetic disorder.