Soft tissue angiomatosis: another PIK3CA-related disorder

Angiomatosis of soft tissue (AST) is a rare, high-flow, intramuscular vascular anomaly. In the context of PTEN hamartoma tumour syndrome (PHTS), this AST is referred to as PTEN hamartoma of soft tissue. Given that AST is observed in patients with no history of PHTS, we hypothesised that non-syndromic AST arises as a consequence of a somatic mutation.

Thirteen patients with histologically confirmed AST were retrospectively studied. Details of the patients' personal and family medical histories and symptoms were retrieved from their medical records. The histological analyses were reviewed and a tissue sample was used for genetic testing. Somatic mutations in the PIK3CA gene (p.Glu542Lys; p.Glu545Lys; p.His1047Arg) were identified in the tissue samples from seven patients, all of whom had unremarkable medical histories and had presented with a single lesion located in the lower limb. Five pathogenic variations in the PTEN gene (mutations: p.Lys263Arg; c.1026+2T>A; p.Ala126Thr; p.Leu108Arg; deletion, log ratio -0.55) were identified in the lesions of four patients; two of the latter had multifocal lesions. All four patients displayed macrocephaly, three boys presented with penile freckles, but none had a family history of PHTS. There were no histological differences between the PIK3CA and PTEN groups.

AST can be related to either PTEN or PIK3CA mutations and may be multifocal in PHTS. AST appears to be a manifestation of PHTS that occurs in early childhood. The patient's medical history and clinical presentation should prompt the physician to perform specific genetic testing.