Somatic PIK3CA Variants Are Associated With Eccrine Angiomatous Hamartomas

Abstract

Objectives: Eccrine angiomatous hamartoma (EAH) is a rare vascular anomaly with mixed eccrine and vascular components, typically identified in children. While benign, EAH can cause significant morbidity and be difficult to treat. The aims of this case series were to identify all patients with EAH that have been seen at the Queensland Children’s Hospital and describe their phenotypic and somatic genotypic details, in an effort to contribute to the limiting understanding and literature surrounding this condition. Methods: Individuals with EAH were retrospectively identified through engagement in a multidisciplinary vascular anomaly clinic in a tertiary Australian children’s hospital. All individuals had a previous histological diagnosis of EAH. High-read-depth sequencing of a panel of 27 genes known to be associated with vascular anomalies was undertaken on affected tissue. Samples were rereviewed by a senior pathologist and geneticist for this study. Results: Five cases of EAH were identified. All were associated with 1 of 3 somatic PIK3CA variants (c.1633G>A;p.Glu545Lys, c.1624G>A;p.Glu542Lys, and c.3140A>G;p.Histo1047Arg) in low allele fractions. These variants have previously been reported in a range of tumors and vascular anomalies, including PIK3CA-related overgrowth spectrum, but not in EAH. Conclusion: Occurrence of somatic PIK3CA variants in EAH provides evidence for a novel gene-disease association and is plausibly the cause of EAH in some individuals. This finding expands the phenotypic spectrum of PIK3CA, contributes to understanding of the pathophysiology of this rare condition, and may avail molecularly targeted therapy in the future.