Fibro-adipose vascular anomaly (FAVA) is a rare and complex vascular malformation that, to date, has hardly been studied, especially in children. The diagnosis and management of FAVA is complicated, and no treatment guidelines have yet been published.

This study aimed to analyze the clinical manifestations and diagnostic and genetic evidence of FAVA and to explore safe and effective treatment with sirolimus in pediatric patients.

We retrospectively analyzed the clinical manifestations and examination data of 18 pediatric patients with FAVA who presented at the Vascular Anomaly Center from September 2019 to February 2023 and summarized the basis on which a diagnosis of FAVA was made. A genetic examination was completed in five cases. A total of 12 cases were treated with oral sirolimus. We analyzed changes in skin lesions before and after treatment and recorded the occurrence of adverse reactions.

Of the 18 patients, 15 were girls and 3 were boys. Most lesions (15 cases) were in the lower extremities, accompanied by varying degrees of chronic pain, functional impairment, contractures, and other functional disorders. Imaging findings can be divided into three categories: focal, focal infiltrative, and diffuse. Histopathological manifestations were malformed vascular fibro-adipose tissue. A genetic examination of five cases identified a PIK3CA somatic mutation. After oral sirolimus treatment, pain and dysfunction associated with the lesions were significantly improved, the lesion volume dramatically diminished, and no obvious adverse reactions occurred.

With the help of imaging, and histopathological and somatic genetic examinations, FAVA can be promptly diagnosed and treated to avoid serious dysfunction. The efficacy and safety of oral sirolimus in the treatment of FAVA deserves further study.