Phyllodes tumors are uncommon biphasic breast tumors with a wide range of clinical behaviors. The distinction between a phyllodes tumor and a fibroadenoma can be difficult. The diagnosis of phyllodes tumor should be suspected in all women who present with a rapidly growing breast lump. Based on the histological characteristics, the World Health Organization (WHO) classifies phyllodes tumors as benign, borderline, or malignant. The risk of recurrence and metastatic potential varies based on histological features. Wide excision or mastectomy is the standard of care ensuring histologically clear margins. Despite the grading criteria defined by the WHO, the management of phyllodes tumors continues to be a challenge.We report the case of a 48-year-old woman who presented to the emergency department with a large and ulcerated phyllodes tumor of the left breast. The tumor size did not allow conservative surgery. The final diagnosis of a borderline phyllodes tumor was made, and, in this case, the patient did not undergo adjuvant treatment.