ESPE Abstracts

Introduction: PIK3CA-related overgrowth spectrum (PROS) encompasses a group of disorders caused by mutations in the PIK3CA gene, leading to abnormal growth and development of various tissues in the body. We report a case of PROS with hypertrophy of the right index finger and upper limb

Case: The case is a 19-month-old boy. He was born at 38 weeks of gestation, weighing 2,554g and measuring 47.2cm in length, with a head circumference of 33.5cm and an Apgar score of 7/9, delivered via vacuum extraction. Hypertrophy of the right index finger was noted at birth, and he was referred to our pediatric orthopedic department at 19 days old. In addition to the right index finger, the entire right upper limb was thicker than the left upper limb, leading to a diagnosis of unilateral hypertrophy and further examination in our department. Initially, considering the possibility of incomplete forms of Beckwith-Wiedemann syndrome, he was followed up with regular abdominal ultrasound to screen for abdominal tumors. As the hypertrophy progressed from the right shoulder to the entire upper limb, MRI imaging was performed at 8 months old, revealing fat proliferation extending into some intermuscular and intramuscular layers. Suspecting Proteus syndrome due to AKT1 abnormalities, a peripheral blood sample was tested using an overgrowth syndrome-related gene panel, but no variants were detected. At 18 months old, partial phalangeal resection and fat removal surgery were performed on the right index finger gigantism. A gene panel test was repeated using DNA extracted from the removed fat, and the known missense variant p.His1047Leu in the PIK3CA gene was identified, leading to a genetic diagnosis of PROS.

Conclusion: This study reports a case of PROS with hypertrophy of the right index finger and upper limb. PI3K inhibitors for PROS are approved only in the United States. It is hoped that it will be approved outside of the United States in the future.