Phyllodes tumors (PTs) are rare tumors of the breast, which encompass both stromal and epithelial components. The maximum incidence is in the fourth decade of life. Most of these tumors are benign, but about one third can be malignant acting as sarcomas. Due to their rarity and atypical clinical behavior (especially for the giant ones), the management of these tumors is usually difficult. We report a case of a 24-year-old woman who presented in the Department of Oncology for rapid increase in volume of the left breast. She had no personal pathological or family history. Initial clinical exam showed a large irregular mass in the left breast of approximately 30 cm and palpable lymph nodes in the ipsilateral axilla. A core needle biopsy for the tumor was performed with histopathological (HP) result that revealed an aspect suggesting fibroadenoma/PT. Contrast-enhanced computed tomography (CT) scan identified lymph node enlargement in the left axilla and a peripheral nodule in the lung about 5.5/3.4 mm with no specific features. The patient was then transferred to the Department of Surgery, where left mastectomy and axillary lymph node sampling were performed. HP result of the surgical specimens confirmed the presence of both fibroadenoma and PT, with clear margins above 1 cm, but recommended immunohistochemistry (IHC) to clearly specify benign versus borderline type. Five lymph nodes out of six resected presented microscopic reactive changes. We performed a search of literature using the keywords "giant", "benign" and "phyllodes". The results were used to summarize and discuss some of the main features of this type of tumors as well as diagnostic and therapeutic difficulties.