A phyllodes tumor (PT) is a rare type of breast tumor known for its diverse biological behavior, which can range from benign to malignant forms. A number of PTs are known for their rapid growth and are classified as fibroepithelial neoplasms with a tendency for local recurrence (1). PTs comprise up to ~0.3 to 1% of all primary breast tumors. Although they can occur at any age, they are most frequently observed in women between 30 and 50 years of age (2).

PTs were initially described in 1838 by Johannes Müller, who named them cystosarcoma phyllodes due to their leaf-like (phyllodial) projections into cystic spaces and their sarcoma-like stromal features (3). However, this term is somewhat misleading, as up to 70% of these tumors follow a benign course and cystic degeneration is uncommon (1). In 1931, the first case of a malignant PT that had spread to the lungs was documented, highlighting the potential of the tumor for malignancy (4).

Recent studies indicate that ~10 to 15% of PTs are malignant. Malignant PTs have a high risk of local recurrence, occurring in up to 30% of cases, and they also have the potential to metastasize. PTs >10 cm in size are referred to as ‘giant’ PTs and comprise ~20% of all cases (1).

PTs are categorized as benign, borderline, or malignant based on a combination of histological features, including stromal cellularity, nuclear abnormalities, mitotic count, stromal overgrowth, necrosis, heterologous sarcomatous elements and tumor margins (5).

Th present study describes the case of a 40-year-old female patient with a rapidly growing, giant, ulcerative malignant PT. The report follows the CaReL guidelines, and all references cited were evaluated for relevance (6,7).

In the present study, a brief review of the literature was also performed. A total of seven case reports (2,5,8-12) on malignant PTs of the breast were reviewed, published between 2024 and 2025 (Table I). The patients were all female, with ages ranging from 19 to 73 years. The majority of the cases (5 out of 7 cases) involved tumors in the right breast, while 2 cases involved tumors in the left breast. Tumor sizes varied widely, from 7.5x7x4.5 cm to as large as 55.5x36x50 cm (weighing 18.6 kg). Clinically, all cases presented with rapid tumor growth. In several cases, rapid growth occurred after a prolonged period of stable tumor size, with final accelerated growth durations ranging from one to three months. BI-RADS categories were reported in 5 cases, typically classified as BI-RADS 4 or 5. The case in the present study aligns with the reviewed cases in terms of clinical presentation, demonstrating a strikingly rapid tumor growth over a short period, expanding to 24x20x17 cm within 2 months. However, it differs in tumor laterality, arising in the left breast, which was less frequently affected in the reviewed cases. Additionally, the lesion was categorized as BI-RADS 5, reinforcing the high radiologic suspicion, which is consistent with the reviewed cases of malignant PTs.

In patients with a large malignant PT, the rapid growth of the tumor can cause varicose veins to appear on the surface of the skin. This can result in poor blood circulation, leading to tissue death, infection and the development of skin ulcers. When the tumor or associated blood vessels rupture, bleeding may occur. A malignant PT is also often accompanied by systemic symptoms, such as anemia and severe weight loss, which may be caused by the metabolic demands of the tumor, infections, or bleeding (10). In advanced cases, patients may develop cachexia, a condition that can lead to multi-organ failure. Dong et al (10) reported a case in which the tumor of the patient became enlarged rapidly and prominently, with surface varicosities, bleeding and infection. The patient in their study also exhibited signs of poor appetite, marked weight loss and anemia (10). Similarly, the case described herein presented with a large, ulcerated area containing necrotic, foul-smelling tissue and active bleeding, features that are characteristic of an aggressive malignant PT and their tendency to cause skin breakdown due to pressure-induced necrosis.

Identifying the subtype of PTs is crucial, as it helps predict the clinical course of the tumor: Benign forms may recur locally, borderline types can also recur with a minimal risk of metastasis, while malignant tumors carry a higher likelihood of spreading (12). Mammography and color Doppler ultrasound are the primary imaging modalities used for evaluating PT. However, in the early stages, both techniques often lack specific findings that clearly indicate the presence of PT (10). In the case in the present study, an ultrasonography revealed a large, heterogeneous mass with internal blood flow and diffuse thickening of the skin, features such as those reported by in the study by Murcia et al (9), who observed that PTs can resemble fibroadenomas and often lack distinctive imaging characteristics to differentiate benign from malignant forms. In the present study, a mammography could not be performed on the affected breast due to the extensive size of the mass and the presence of surface ulceration, an imaging limitation frequently encountered in advanced tumors. A comparable situation was described by Kaiser et al (11), where a PT had expanded to 55 cm. These limitations in imaging underscore the importance of histological examination for definitive diagnosis (11).

A definitive diagnosis of PTs requires a CNB, which reveals characteristic histological features, including a leaf-like architecture formed by stromal overgrowth that projects into papillary structures resembling leaf blades (9). Fine needle aspiration has also been considered a useful preoperative tool for diagnosing PTs. Cytological findings typically include fibromyxoid stromal fragments rich in spindle cells, along with clusters or sheets of benign ductal epithelial cells without atypia, often accompanied by myoepithelial cells (1). In the case in the present study, CNB identified a fibroepithelial lesion with stromal myoid differentiation, which raised the possibility of a PT. Distinguishing PT from other fibroepithelial tumors, such as fibroadenomas or metaplastic carcinoma, can be challenging before surgery, as noted by Haddad et al (5). Immunohistochemical analysis was essential in confirming the diagnosis in the present case. p63 staining was negative in both the ductal and stromal cells, but remained positive in the myoepithelial cells. AE1/AE3 was positive in the benign ductal epithelial components and negative in the stromal cells. In contrast, the stromal cells showed strong, diffuse cytoplasmic staining for SMA and SMMHC, supporting smooth muscle differentiation (Fig. 2). These findings are consistent with those reported by Lissidini et al (1) (2022) and Haddad et al (5), who emphasized the critical role of immunohistochemistry in determining stromal cell lineage and distinguishing malignant PTs from metaplastic carcinomas, particularly in cases with prominent spindle cell features.

Current management strategies for PTs reveal a lack of consensus and limited evidence-based guidelines, particularly as regards the optimal surgical margins required to achieve complete excision and reduce the likelihood of recurrence. Traditionally, treatment has involved wide local excision with margins >1 cm, with tumor size often influencing the decision to proceed with mastectomy. Malignant PTs are known for their aggressive nature, with a high risk of local recurrence and potential for metastasis to the lungs, bones and LNs. However, emerging data suggest that margins <1 cm may be adequate for effective tumor removal, potentially making breast-conserving surgery a viable option in selected cases (8). In the case presented herein, the patient underwent wide local excision. This treatment approach is consistent with the current literature, which emphasizes that complete surgical resection with negative margins remains the primary method for managing malignant PTs. As highlighted by Lissidini et al (1) and Haddad et al (5), the most critical factor influencing local recurrence is the adequacy of surgical margins, with a general recommendation of at least 1 cm. Due to the elevated risk of recurrence, adjuvant radiotherapy was administered following the initial excision. This decision aligns with findings from the study by Kaiser et al (11), who underscored the importance of radiotherapy in enhancing local disease control, particularly for large or marginally resectable tumors.

Despite initial aggressive local treatment, the patient in the present study experienced a recurrence within 1 year, identified through follow-up imaging and confirmed by CNB. Recurrence in malignant PTs is relatively common, with reported rates as high as 30%, particularly in cases with inadequate surgical margins or tumors characterized by high mitotic activity and stromal overgrowth, as documented by Lissidini et al (1) and Dong et al (10). Given the recurrence, the patient underwent a modified radical mastectomy, a more extensive procedure involving the removal of the breast along with regional LNs. While axillary LN metastasis in malignant PTs is uncommon, as noted by Vicentini et al (12), LN dissection may be warranted in select cases with clinically suspicious nodes. In the case in the present study, a lymphadenectomy was performed due to suspicious findings, but no LN metastases were identified on the histopathological examination.

The present case report is distinguished by the rare coexistence of extensive ulceration, recurrence following wide local excision with adjuvant radiotherapy, and stromal myoid differentiation within a giant malignant phyllodes tumor. These uncommon features occurring together make the case a valuable addition to the limited literature on the biological variability and aggressive behavior of malignant phyllodes tumors. In conclusion, the diagnosis and management of malignant PTs can be challenging due to their rarity and unpredictable clinical behavior. Even with aggressive treatment, these tumors carry a significant risk of recurrence, highlighting the importance of vigilant clinical follow-up and multidisciplinary care.