Summary: Phyllodes tumors are rare fibroepithelial breast tumors representing less than 1% of all breast malignancies, with an extremely uncommon presence in the pediatric population.1 Although prognosis is favorable following excision given their indolent course, they often grow rapidly and frequently recur. As such, they can present unique oncologic and reconstructive challenges. Herein we present a case of a malignant phyllodes tumor in an 11-year-old girl treated with total skin-sparing mastectomy and adjustable saline implant, and explore the reconstructive challenges of this unique case.