Phyllodes breast tumours: diagnostic challenges, surgical approaches, and post-treatment considerations—a case report on insidious clinical presentation, progression, histopathological and radiological tumour transformation

Introduction

Phyllodes tumours are rare fibroepithelial neoplasms arising from stromal components of the breast. These tumours constitute approximately 1% of all breast tumours and represent several unique challenges in terms of diagnosis, surgical management and post-treatment care (1). Phyllodes tumours are characterized by their distinct histopathological features, including a combination of epithelial and stromal components, and their potential for aggressive clinical behaviour (2). The term “phyllodes” is derived from the Greek word meaning “leaf-like”, which describes the characteristic frond-like growth pattern of the stromal component. Phyllodes tumours can be categorised into three histological grades: benign, borderline and malignant (3). The histological grading is based on a various histologic features including stromal cellularity, nuclear atypia, mitotic activity, stromal overgrowth, and the appearance of tumor margins. However, there are no specific criteria or clear thresholds for these individual histologic parameters. As a result, diagnosing phyllodes tumour through morphological assessment is challenging, especially when distinguishing phyllodes tumours from fibroadenomas (4).

A diagnostic challenge with phyllodes tumours is their clinical and radiological similarities to common benign and malignant breast lesions (5). The initial clinical presentation can mimic fibroadenoma, a commonly encountered benign tumour of the breast (6). Both often present on radiological imaging with well-defined margins, oval shape and a solid mass appearance. Additionally, the radiological features of phyllodes tumours can vary widely (7). They range from completely cystic to predominantly solid masses, with variations including internal septations, and necrotic areas, which leads to further diagnostic ambiguity (8). Histopathological examination remains the gold standard for accurate diagnosis, necessitating careful assessment by experienced pathologists to determine the malignant potential (9).

Surgical management and treatment pose a significant clinical dilemma due to the variability in clinical tumour behaviour and the rarity of the individual subtypes. The primary treatment modality is surgical resection, with the extent of surgery being dictated by tumour size, histological characteristics and patient-related factors (10,11). The challenge lies in achieving optimal surgical margins, minimizing the risk of recurrence or metastasis while ensuring an aesthetically acceptable cosmetic outcome. Given the rarity of these tumours, consensus regarding the ideal extent of resection, axillary lymph node assessment, and the role of adjuvant therapy is based on a low level of evidence (12,13).

This case report presents three patients with phyllodes tumours of different subtypes. It demonstrates the clinical presentation, radiological imaging, histopathology and surgical approach, and aims to exemplify some of the diagnostic and surgical challenges of this rare tumour.

The aim is to contribute to the existing literature by discussing the complexities associated with correct diagnosis and management of phyllodes tumours, emphasising the need for a multidisciplinary team approach involving radiologists, pathologists, breast surgeons, plastic surgeons and oncologists. By shedding light on this rare and enigmatic entity we hope to enhance the understanding of phyllodes tumours and improve patient outcome through evidence-based diagnostic and therapeutic interventions. We present these cases in accordance with the CARE reporting checklist (available at https://abs.amegroups.com/article/view/10.21037/abs-24-8/rc).

Case presentation

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patients for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Case 1

A 58-year-old female was referred to the Department of Breast Surgery with a red, swollen and tender right breast. The symptoms had persisted for 14 days prior to admission, and she was initially treated with antibiotics on the suspicion of an infection. She remained asymptomatic. According to the patient no mass in the breast could be palpated initially. The patient had a medical history of hypertension, previous benign cysts in both breasts and had undergone cosmetic augmentation mammoplasty 15 years prior.

On admission, clinical inspection and palpation of the right breast revealed a giant mass estimated at 12 cm in diameter, located centrally in the breast behind the nipple-areola complex. The skin was stretched, and the breast was deformed. The contralateral breast was unaffected. No enlarged lymph nodes were found in the axillary or the head and neck region on clinical palpation.

An ultrasound was performed and showed a large heterogenous mass involving most of the breast tissue with no clear margins of invasion, classified as BI-RADS 5 (Breast Imaging-Reporting and Data System). The breast implants were both found to be ruptured, an extracapsular rupture on the right side and an intracapsular rupture on the left. Due to the clinical suspicion of a phyllodes tumour, a magnetic resonance imaging (MRI) of the breast was performed (Figure 1A). Furthermore, a core needle biopsy of the breast confirmed the suspicion of a phyllodes tumour with the subtype classified as a borderline tumour.

Figure 1 Case 1. (A) Magnetic resonance imaging of the breast, sagittal section, showing the phyllodes breast tumour and a breast implant posterior to the tumour. (B) Preoperative clinical presentation with an enlarged right breast with a tumour mass estimated to 30 cm in diameter. (C) A positron emission tomography and computed tomography, axial section, showing the phyllodes breast tumour measuring 12 cm × 12 cm × 13 cm in diameter with no deep invasion of the underlying pectoralis muscle. The breast implant is visualised posterior to the tumour. (D) Perioperative total mastectomy of the right including partial resection of the pectoralis muscle. (E) The defect measuring 30 cm × 25 cm after excision. (F) Four-month follow-up and postoperative result.

Nine days after the initial presentation the mass was evaluated clinically to have enlarged to 30 cm in diameter, showing an alarming growth potential (Figure 1B). A ¹⁸F-flourdeoxyglucose (FDG) positron emission tomography and computed tomography (PET-CT) scan was also performed which revealed a tumour measuring 12 cm × 12 cm × 13 cm in diameter with no deep invasion of the underlying pectoralis muscle but presenting several pathological looking lymph nodes in the right axilla and in the subpectoral area (Figure 1C).

At a multidisciplinary team conference consisting of breast surgeons, plastic surgeons, sarcoma surgeons, radiologists, pathologists and oncologist a surgical resection of the tumour without immediate breast reconstruction was decided as initial treatment. The patient underwent a total mastectomy including removal of breast implant and partial resection of the pectoralis muscle (Figure 1D). No invasion of deeper layers of the chest wall was identified clinically perioperatively. After excision, the defect measured 30 cm × 25 cm and could be closed primarily (Figure 1E). Furthermore, the breast implant on the left side was explanted. Four lymph nodes from the right axilla were resected and none of these showed evidence of malignancy with peri-operative frozen section analysis.

The final pathology diagnosis showed a malignant phyllodes tumour with margin-negative surgical resection and four lymph nodes without malignancy.

Clinical follow-up was planned during a multidisciplinary conference with MRI scans and PET-CT scans every three months for a minimum of five years and clinical examination in the sarcoma unit (Figure 1F). At one-year postoperative follow-up, there was no sign of recurrence and the patient is currently awaiting delayed breast reconstruction.

Case 2

A 44-year-old female was referred to the Department of Plastic Surgery due to an extensive tumour in her left breast. She had no previous medical history but had noticed a small palpable mass in her left breast one year prior to presentation.

On clinical examination a giant mass measuring approximately 20 cm in diameter was found in the left breast. The contralateral breast was unaffected and no enlarged lymph nodes were detected in the axillary region or the head and neck region upon clinical palpation (Figure 2A).

Figure 2 Case 2. (A) Clinical presentation on first referral showing an enlarged left breast with a giant tumour mass measuring approximately 20 cm in diameter. (B) PET-CT, coronal section, showing a tumour mass measuring 18 cm × 12 cm × 15 cm in the left breast. (C) PET-CT, axial section, showing a multilobed tumour with multiple necrotic areas. (D) Preoperative clinical presentation, one year after initial referral, with a massive tumour of approximately 40 cm × 30 cm with ulcers and necrotic tissue on several sites. (E) PET-CT, coronal section, showing a hypodense lobed tumour with the lateral border protruding outside of the scanned area. (F) PET-CT, axial section, the tumour measuring 23 cm × 17 cm × 30 cm with multiple necrotic areas involving the pectoralis major and minor muscles in close proximity to the thoracic wall with no clear margins for involvement of the thoracic wall. (G) Perioperative imaging after extensive surgical resection of the tumour, the pectoralis major and minor muscles, the lateral part of the latissimus dorsi and the serratus muscle together with axillary lymph node dissection. The defect measured 26 cm × 28 cm. (H) Perioperative reconstruction with a thoraco-abdominal rotation flap, combined with a split skin graft. (I) Two-month follow-up and postoperative result. PET-CT, positron emission tomography and computed tomography.

A mammography of the left breast was performed and showed a homogenous round mass measuring 17 cm in diameter. Furthermore, a core needle biopsy of the breast showed atypical histological changes. A subsequent MRI scan and ¹⁸F-FDG PET-CT scan revealed a radiological multilobed tumour measuring 18 cm × 12 cm × 15 cm with multiple necrotic areas. The scans showed the tumour to be in contact with the thoracic wall, the pectoralis muscle and the intercostal muscles with no clear margins of invasion, classified as BI-RADS 5 (Figure 2B,2C). The scans showed no sign of local or distant metastasis. Based on these findings the diagnosis was suspected to be sarcoma or giant phyllodes tumour.

The case was discussed in a multidisciplinary team conference comprising of breast surgeons, sarcoma surgeons, plastic surgeons, radiologists, pathologists, and oncologists. The team strongly recommended surgical management, but the patient declined and opted for alternative treatment.

One year later, the patient was readmitted due to deterioration in her general health. She had been bedridden for the past six months due to pain from the growing tumour. Inspection and palpation revealed a tumour of approximately 40 cm × 30 cm with ulcers and necrotic tissue on several sites (Figure 2D). A core needle biopsy was repeated and raised the suspicion of a malignant phyllodes tumour.

A ¹⁸F-FDG PET-CT scan was performed which showed a hypodense lobed tumour with the lateral border protruding outside of the scanned area (Figure 2E,2F). The tumour had grown to a minimum of 23 cm × 17 cm × 30 cm with multiple necrotic areas involving the pectoralis major and minor muscles and in close proximity to the thoracic wall with no clear margins for involvement of the thoracic wall. Lymph nodes in the axillary region and in the subpectoral area were pathologically enlarged.

Extensive surgical resection was performed excising the tumour, the pectoralis major and minor muscles, the adjacent part of the latissimus dorsi and the serratus muscle together with axillary lymph node dissection. The defect measured 26 cm × 28 cm postoperatively and reconstruction was done using a thoraco-abdominal rotation flap, combined with a split skin graft (Figure 2G-2I).

The final pathology diagnosis confirmed a malignant phyllodes tumour with margin-negative surgical resection and all lymph nodes without malignancy. Due to the size of the tumour the patient was recommended to undergo adjuvant radiotherapy, which she refused. Clinical follow-up was planned during a multidisciplinary conference with MRI scans and PET-CT scans every three to six months for a minimum of five years and clinical examination in the sarcoma unit. At one-year postoperative follow-up, there was no sign of recurrence.

Case 3

A 40-year-old female was referred to the Department of Breast Surgery due to a growing mass in her right breast. The mass was noticed nine years ago and diagnosed as a benign fibroadenoma. The patient had no previous medical history.

On clinical examination a mass measuring approximately 4 cm was found in the right breast. The contralateral breast was unaffected and no enlarged lymph nodes were detected in the axillary region or the head and neck region upon clinical palpation (Figure 3A). A mammography of the right breast was performed and showed a 5.1-cm benign process and a 1.1-cm benign process, both classified as BI-RADS 2. Due to enlargement of the palpable mass, a core needle biopsy was repeated, which confirmed the previous diagnosis of a benign fibroadenoma.

Figure 3 Case 3. (A) Clinical presentation before final surgery and after initial breast conserving surgery and re-operation. (B) Magnetic resonance imaging of the breast before final surgery, sagittal section, showing surgical sequelae and no residual tumour with an intact fascia. (C) Magnetic resonance imaging of the breast before final surgery, axial section, showing surgical sequelae and no residual tumour with an intact fascia. (D) Perioperative excision of the lateral mammary tissue including the pectoralis muscle and the fascia of the serratus muscle. (E) Oncoplastic breast reconstruction with a lateral intercostal artery perforator flap. (F) One-month follow-up and postoperative result, lateral view.

A breast conserving surgery using the inframammary fold incision was performed and the final histological diagnosis revealed a borderline phyllodes tumour with no clear surgical margins. A re-operation was performed to achieve clear surgical margins, but tumour cells were still present in the lateral and inferior quadrant. The 1.1-cm benign process was also removed during this re-operation.

The patient was discussed in a multidisciplinary team consisting of breast surgeons, plastic surgeons, sarcoma surgeons, radiologists, pathologists and oncologists and the patient was recommended a breast conserving surgery and oncoplastic breast reconstruction along with a preoperative MRI scan. The MRI scan showed surgical sequelae and no residual tumour with an intact fascia (Figure 3B,3C). No enlarged axillary lymph nodes were detected. Surgery was performed, and the lateral mammary tissue including the pectoralis muscle was resected along with the fascia of the serratus muscle (Figure 3D). Oncoplastic breast reconstruction was performed with a lateral intercostal artery perforator flap (Figure 3E,3F).

The final pathology diagnosis showed no evidence of residual tumour. Clinical follow-up was planned during a multidisciplinary conference with mammography every year for a five-year period and clinical examination in the breast surgery unit. At one-year postoperative follow-up, there was no sign of recurrence.

Discussion

Due to the low incidence of malignant phyllodes tumours, treatment recommendation is often based on case reports. Most phyllodes tumours of the breast are benign, however distinction between benign, borderline and malignant phyllodes tumours impose a serious challenge (1). Since fine needle aspiration cytology has low sensitivity and specificity in detecting phyllodes tumour cells, core needle biopsy is preferred (14). However, it is not accurate in differentiating between fibroadenoma and phyllodes tumour, hence postoperative re-classification often occurs. In two of the reported cases, it was not possible to subclassify the tumours prior to surgery, and both tumours were re-classified as malignant in their final pathology. In case 3 the tumour was misclassified as benign fibroadenoma, the correct histopathology diagnosis was obtained postoperatively as a borderline phyllodes tumour. In case 1 and case 2 the preoperative imaging raised the suspicion of nodal metastasis, leading to lymph node resection in both cases. However, none of these showed evidence of malignancy.

Hence, the present case report is highly representative of the diagnostic challenges prior to surgery.

Early detection and correct diagnosis are essential since all cases should be evaluated in a multidisciplinary team setting with minimum delay in treatment. Case 1 and case 2 both illustrate the potential rapid evolvement of this rare illness and underlines the importance of early detection. In all three cases surgical excision with clear margins were achieved. The extension of surgery has been discussed in other studies, and most authors agree that ≥1 cm tumour-free margins are necessary (14,15). A study from Boutrus et al. showed that adjuvant radiation therapy significantly improved local recurrence free survival after margin negative wide local excision (16). In our case series, two out of three patients had pathological looking lymph nodes on imaging but no lymph node metastases were found at final pathology despite a considerable size of a malignant phyllodes tumour. This underlines the minimal risk of lymphatic spread, and lymphatic staging does not seem to be indicated.

Follow-up regimens were chosen according to tumour grading based on local guidelines. Borderline phyllodes tumour was planned for follow-up with annual mammography for a five-year period since previous nationwide retrospective data have shown a low recurrence rate and a low malignant recurrence in benign and borderline phyllodes tumours (17). The malignant phyllodes tumours were planned for MRI and PET-CT scans with three to six months intervals for a five-year period in accordance with the national sarcoma guidelines as no general consensus on follow-up regimens for malignant phyllodes tumours exist.

Decision on immediate or delayed breast reconstruction should be evaluated on a case-by-case basis and by the multidisciplinary team. Performing an immediate or delayed breast reconstruction should be offered with an individualized approach according to the type of tumour, adjuvant therapy and of course relying on the patient demand. Current literature does not suggest a higher recurrence rate after immediate breast reconstruction (18,19).

Conclusions

This case report highlights the accelerated tumour growth in delayed diagnosis and patient refusal of treatment in the management of malignant phyllodes tumour. Timely multidisciplinary interventions are crucial to optimize outcomes and address both oncological and reconstructive aspects of care. Phyllodes tumours present unique diagnostic challenges and require careful evaluation by experienced pathologists. Surgical management poses a clinical dilemma due to the variability in tumour behaviour, the difficulty of assessing subtype pre-operatively and the absence of established guidelines necessitates a multidisciplinary approach. By sharing comprehensive case reports like this we can enhance the understanding of phyllodes breast tumours and improve patient outcomes through collaborative and evidence-based diagnostic and therapeutic interventions.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://abs.amegroups.com/article/view/10.21037/abs-24-8/rc

Peer Review File: Available at https://abs.amegroups.com/article/view/10.21037/abs-24-8/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://abs.amegroups.com/article/view/10.21037/abs-24-8/coif). T.M.E.D. serves as an unpaid editorial board member of Annals of Breast Surgery from July 2023 to June 2025. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patients for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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