Phyllodes tumors typically manifest as rapidly growing breast lumps, with other symptoms and signs that are non-specific, making clinical diagnosis challenging. Distinguishing between Phyllodes Tumors (PT) and fibroadenomas through ultrasound (US) and mammography can be difficult. On mammography, a PT typically presents as a well-circumscribed, hyperdense or isodense, round or oval mass. Conversely, significant sonographic features favoring the diagnosis of Phyllodes Tumors (PT) over fibroadenomas include a lobulated shape, a heterogeneous internal echo pattern, and the absence of microcalcifications. Importantly, neither sonography nor mammography can reliably distinguish between malignant and benign PTs [8,9]. While FNAC is not a reliable method to distinguish a fibroadenoma from a phyllodes tumor, core needle biopsy has been proposed as a more effective approach for preoperative diagnosis. Nevertheless, the definitive diagnosis should ultimately rely on the pathological examination of surgical specimens [10].

Immunohistochemistry reveals distinctive features, with the expression of p53, Ki-67, CD117, EGFR, p16, and VEGF showing the highest levels in malignant phyllodes tumors and the lowest positivity in benign cases [11]. Some authors have delved into the genetic landscape of fibroepithelial lesions, revealing a similarity in the profiles of benign phyllodes tumors to fibroadenomas. In contrast, malignant phyllodes tumors were identified as claudin-low and basal-like [12]. Genome-wide analyses involving DNA copy number variations and genomic sequencing have unveiled notable amplifications and deletions. In addition to loss-of-function mutations in TP53, deleterious mutations in RB1 and NF1, mutations in PIK3CA and ERBB4, and high-level copy number variations of EGFR have been detected in borderline/malignant tumors [13,14].

Hawkins et al. and Kessinger et al. established a robust correlation between stromal overgrowth and metastasis, noting that all metastatic lesions contained only stromal elements. Phyllodes tumors inherently harbor recurrence and/or metastatic potential, varying based on histologic grade. Clinical behavior may not always align with histologic appearance, as both malignant and borderline tumors exhibit metastatic capabilities [15,16]. Distant metastasis is observed in 25% of malignant phyllodes tumors, compared to 10% in all phyllodes tumors. Interestingly, 3–12% of metastatic cases emerge at the time of presentation or as late as more than 10 years later [17]. The most frequent sites for metastasis in malignant phyllodes tumors are the lung (66%), bones (28%), brain (9%), and liver [18,19]. Rare instances of distant metastasis involve the adrenal glands, kidney, skin, ovary, heart, pleura, oral cavity, duodenum, pancreas, tonsillar, and para-aortic nodes. Similar to other sarcomas, malignant phyllodes tumors primarily metastasize hematogenously, with lymphatic spread being exceptionally rare [20]. As per NCCN guidelines, the recommended treatment for phyllodes tumors, encompassing benign, borderline, and malignant subtypes, involves local surgical excision with tumor-free margins of 1 cm or greater. Lumpectomy is the preferred surgical approach, with total mastectomy deemed necessary only if lumpectomy cannot achieve negative margins. Some literature also describes a more radical approach, involving excision of the tumor with a 2-cm margin, encompassing overlying skin and a portion of the underlying pectoralis major muscle, aiming to mitigate local recurrence [36].

Due to the rare occurrence of lymph node metastasis in malignant phyllodes tumors, routine axillary lymph node dissection is not a common practice. In some cases, particularly in patients undergoing total mastectomy, sentinel lymph node biopsy or axillary sampling might be performed. According to the literature, the reported incidence of axillary lymphadenopathy is approximately 20–25% [21]. Axillary lymphadenopathy is frequently indicative of an infected necrotic tumor rather than metastasis [6]. However, in some instances, malignant transformation within the epithelial component of phyllodes tumors can occur, leading to the development of an associated invasive or in-situ component (reported at 1.1 to 6%) and, consequently, metastatic axillary lymph nodes [37].

Studies conducted by Bennett et al., Ramakant P et al., Chaney AW et al., and Narayanakar RP et al., involving clinicopathological data and management of phyllodes tumors, included 30, 160, 101, and 162 patients, respectively. In these studies, lymphatic spread was also evaluated, and they showed no evidence of nodal metastasis [20-22].

In the literature, only a sparse number of cases featuring malignant phyllodes (without an associated invasive component) with involvement of metastatic lymph nodes have been reported.