## 3 Case Discussion  
Due to the high incidence of fibroadenomas in all breast tumors, phyllodes tumors are often misdiagnosed and the operative time is delayed. The fact that, most of the time, tumor masses are not painful, makes patients neglect treatment and delay their presentation to the doctor. The rapid growth of the tumor, with breast deformation, is the reason that makes patients seek medical assistance. The etiology of these tumors remains unknown. Studies show that the left breast is possible to be more affected than the right one [15]. An ultrasound and mammography may raise the suspicion of a phyllodes tumor, although studies show that 20% of the phyllodes tumors are diagnosed by the screening mammography [16]. More recently, the mammographic texture analysis has provided information on how to differentiate benign phyllodes tumors from G2/G3 malignant tumors and may be useful for planning surgery [17]. Tumors are usually multinodular, and may turn into multicenter, mobile, painless tumor masses with sizes larger than 4.1 cm, and well-defined margins [18]. Tumors larger than 10 cm are considered giant tumors, being found in 20% of the total phyllodes tumors [19]. Tumors measuring more than 30 cm have also been reported. Some cases identified in men have also been published [20]. The fine needle biopsy, even ultrasound-guided, is inconclusive due to the false negative results. The core-needle biopsy is much more reliable, but it also has a rate of false-negative results as high as 25-30% [21; 22; 23]. It is difficult to differentiate fibroadenomas from the phyllodes tumor by biopsy, as it is impossible to assess whether tumor margins are perfectly circumscribed or have irregularities, with both tumors having the same characteristics of increased stromal cellularity. Moreover, the distinction between benign and borderline phyllodes tumors based on microscopic characteristics may be subjective [24]. An histopathological diagnosis of malignant phyllodes tumors is based on the presence of a marked stromal cellularity, cell atypia, infiltrative margins, and an intense mitotic activity of at least 10/10 high-power fields (HPF), compared to the borderline ones which do not exceed 7-9 mitoses/10 HPF. The literature shows a higher percentage of malignant phyllodes tumors in the case of recurrences [25]. The tumor growth can also be influenced by trauma, lactation, an increase in the estrogenic activity, and an increased endothelin-1 level [26]. The genetic mutations (TP53) in the Li-Fraumeni syndrome are also present in patients with phyllodes tumors, suggesting the possibility of a genetic predisposition [27]. So far, no immunological marker has been identified to distinguish between benign and malignant tumors. For more difficult cases, the Ki67 labeling index and p53 immunohistochemical staining, along with the EGFR and c-Kit expression, increased the number of chromosomal gains (e.G.4q12), 9P deletion (loss of a p 16 INK4a), stromal p16 and stromal/epithelial pRb expression, methylation of RASSF1A and TWIST, which proved to be useful, but much more studies are necessary to predict a clinical behavior [28]. Figure 7: Appearance at 14 months after surgery. The gold standard treatment for phyllodes tumors is total excision with the tumor margins free of the disease, without an axillary lymph node dissection. There are authors who consider that the NCCN guidelines advocating a 1 cm margin for surgical therapy in the phyllodes tumor is an over-treatment [29]. Small tumors located in large breasts can be excised with wide safety limits, with safety margins free of the disease larger than 1 cm, and breasts can be reconstructed by oncoplastic surgery techniques. Tumors that spread on more than \({}^{1}/_{2}\) of the breast volume, which are recurrent, are candidates for total mastectomy and immediate reconstruction, usually by a tissue expander or breast implant placed at the submuscular level.