Primary breast neoplasms are rare in adolescent females, most of which are benign. Phyllodes tumors constitute a remarkably small subset of breast neoplasms (0.3-0.9%) with malignant phyllodes tumors being even more uncommon. Malignant phyllodes tumors tend to progress rapidly though only 1.5% metastasize. They are also associated with a higher rate of recurrence than their benign counterparts, underlying the importance of adequate surgical margins. It is therefore imperative to be able to identify these tumors early allowing for prompt resection and close follow-up. Here, we present the rare case of a 17-year-old female presenting with a rapidly enlarging breast mass, which was ultimately found to be a malignant phyllodes tumor. We further performed a review of the literature to highlight only 22 other cases reported in adolescent females.