First Pediatric Use of Pegulicianine for Fluorescence-Guided Surgery in Li-Fraumeni-Associated Rhabdomyosarcoma.

Rhabdomyosarcoma is the most common childhood soft tissue sarcoma. We report a 4-year-old male child with Li-Fraumeni syndrome and germline tumor protein 53 gene (TP53) mutation presenting with a supraclavicular mass. Pathology revealed embryonal rhabdomyosarcoma with anaplastic features and positive margins. Although standard management includes radiotherapy for positive margins, Li-Fraumeni syndrome markedly elevates radiation-induced secondary malignancy risk. Therefore, re-resection was recommended to achieve clear margins and limit radiation exposure. Because the margin location was uncertain, the fluorescent agent pegulicianine (LUMISIGHT) was administered for intraoperative tumor identification. This represents the first documented pediatric use of this agent. The patient tolerated pegulicianine and intraoperative imaging without complications.