A Four-Year-Old Female With a Rare P53 Gene Mutation Diagnosed With Li-Fraumeni Syndrome and Concomitant Metastatic Rhabdomyosarcoma: A Case Report.

Li-Fraumeni syndrome (LFS) is an autosomal dominant disorder that often results from mutations that impair the functions of the tumor suppressor gene p53. LFS is categorized as a hereditary cancer predisposition syndrome in which patients frequently suffer from an elevated degree of onset and incidence of neoplastic malignancies. Among the different pathogenic variants of LFS, TP53 is one of the most frequently encountered ones. A four-year-old female is reported in this vignette, with a rare c.375+1G>T pathogenic variant in the TP53 gene consistent with an LFS diagnosis. To our knowledge, this is the first reported "germline" example of this variant in the literature. Initially, the patient presented to the emergency department due to concerns of progressive swelling and firmness of a mass in the patient's right abdomen. Further imaging and analysis revealed a rhabdomyosarcoma of the pelvis secondary to LFS. In addition to this, the patient's brother and mother both were positive for the same LFS mutation allowing us to make a definitive LFS diagnosis. Our patient then underwent neoadjuvant chemotherapy, radiotherapy, and eventually a resection of the main neoplastic lesion. Among pediatric LFS patients, the risk of suffering secondary and/or multiple cancers is pathologically elevated. That said, it is crucial to perform genetic analysis tests for pediatric oncology patients, especially those patients with hereditary predisposition to cancers. Considering the poor prognosis of most TP53 mutations, it is of utmost importance to implement prompt and systematic care for patients diagnosed with LFS.