A very rare case report: Rapidly recurrent metaplastic carcinoma of the breast

Authors

Abstract

Metaplastic breast cancer (MBC) is a rare subtype of invasive breast cancer characterized by mixed epithelial and mesenchymal differentiation. Most MBC subtypes have poor survival rates and a worse prognosis than triple-negative breast cancer. They often respond poorly to treatments that other breast carcinomas respond to. Imaging features of MBC may not be distinguishable from invasive ductal carcinoma and benign lesions. Early diagnosis of MBC is crucial for deciding on a treatment strategy and predicting prognosis. Literature data on MBC are limited, and MBC patients are still not adequately included in clinical studies. In this case report, we aimed to present the clinical and radiological features of a patient who developed recurrent metaplastic breast carcinoma on the left anterior chest wall in a short time after left-sided total mastectomy for metaplastic breast carcinoma.

Keywords

Introduction

Metaplastic breast carcinoma (MBC) is a rare and heterogeneous group of primary breast malignancies, constituting less than 1% of all invasive breast carcinomas ¹. This carcinoma is distinguished by the presence of non-epithelial cellular components alongside epithelial carcinoma. Recently, the WHO breast tumors working group introduced a descriptive classification for MBC, encompassing low-grade adenosquamous carcinoma, fibromatosis-like metaplastic carcinoma, spindle cell carcinoma, metaplastic carcinoma with mesenchymal differentiation, and mixed metaplastic carcinoma ².
MBC is frequently identified as a subtype of triple-negative breast cancer (TNBC) ³. Unfortunately, it is associated with a poorer prognosis compared to non-metaplastic TNBC. The recurrence risk is twice as high, and both disease-free survival (DFS) and overall survival (OS) rates are lower than those observed in non-metaplastic triple-negative breast cancer (TNBC) and other invasive carcinomas ^2,4. These findings highlight the intricate histological and molecular characteristics of MBCs ⁵. Typically, MBCs are high-grade tumors that present as large masses. While most cases arise de novo, there have been reports of occurrences originating from pre-existing lesions, including complex sclerosing lesions, papillomas, and breast adenomas ³.
Comparative studies evaluating the clinicopathological and prognostic outcomes of MBC and invasive ductal carcinomas indicate a worse prognosis for MBC, with a heightened risk of disease recurrence and poorer overall survival ⁶. Factors such as the stage at diagnosis, estrogen receptor (ER) status, and adjuvant therapy significantly influence recurrence rates. MBC carries a high risk of recurrence following initial treatment, with limited evidence supporting the efficacy of selective estrogen receptor modulators or aromatase inhibitors post-treatment ⁶. Due to the substantial risk of local recurrence, reported to range between 35-62% within the first 2-5 years, modified radical mastectomy (MRM) or mastectomy is preferred over breast conservation surgery (BCS) ⁶.

Case Presentation

In 2017, a 67-year-old female patient was admitted to our hospital with a mass in her left breast. After the biopsy, histopathological examination diagnosed her as TNBC (ER (-), PR (-), CerbB2 (-), and Ki-67: 10-15%). A decision was made to operate after neoadjuvant chemotherapy (NAC). However, the patient did not accept the surgical operation because the mass regressed completely after NAC. She applied to us again in 2023 because the mass grew again, and the patient underwent a left total mastectomy procedure. As a result of the pathology examination of the patient’s mastectomy material, it was evaluated as grade 2 metaplastic carcinoma. (ER (-), PR (-), CerbB2 (-), p53 (-), p63 (-), CK5/6 (+), Ki-67: 5-6%). Less than 1 year after surgery (approximately 7 months) in 2024, the patient applied to us with the complaint of increasing hardness in the left anterior chest wall. During the physical examination, while the right breast examination was normal, a hard, irregular lump-shaped mass lesion of approximately 5 cm, fixed to the anterior chest wall, was detected at the junction of the left anterior chest wall and axilla.
Ultrasonography examination revealed a hypoechoic mass lesion with a heterogeneous internal structure and regular lobulated contours on the left anterior chest wall that did not fit into the probe area and measured approximately 60x50 mm at its widest portion (Figure 1). In the lateral neighborhood of this lesion, 2-3 more lesions of similar nature, the largest of which was approximately 55x35 mm in size, were observed. In the left axilla, 2-3 lymphadenopathies with a pathological appearance and an internal structure similar to the primary mass, the largest of which was approximately 35 mm in diameter, were observed. The biopsy result of the mass was evaluated as grade 3 metaplastic carcinoma. (ER 11-20%, PR 11-20%, HER (-), p53 and “wild” type, GATA-3 focal (+), CK5/6 (+), Ki-67 20%).
This report presents a single descriptive case without the inclusion of identifiable personal information. As such, ethical approval was not required for this case presentation.
Axillary lymph node evaluation with PET-CT examination (July 2024) revealed multiple lymphadenopathies in levels I, II, and III. In Stage I, multiple lymph nodes with hypermetabolic character, some with conglomerated appearance, measuring approximately 5.5x5 cm in size, were observed (Figure 2). Chemotherapy could not be administered due to the patient’s accompanying comorbidities (hypertension, Diabetes mellitus, chronic renal failure). The patient and his relatives did not accept the recommended radiotherapy.
This report presents a single descriptive case without the inclusion of identifiable personal information. As such, ethical approval was not required for this case presentation.

Discussion

Although the global epidemiology of MBC remains relatively unclear, increasing case reports continue to provide valuable insights. These tumors tend to present at a more advanced stage compared to other breast cancer types, and most MBC subtypes are linked to poorer survival outcomes ⁵. Large, newly developed, or rapidly growing lesions with complex echogenicity observed on ultrasound necessitate further evaluation through image-guided biopsy for a definitive diagnosis ⁶.
MBC is a rare and highly heterogeneous malignancy, exhibiting significant histological variability and marked aggressiveness. It demonstrates a diminished response to conventional chemotherapy and has a worse overall prognosis compared to TNBC and other invasive breast carcinoma subtypes. Managing MBC is particularly challenging due to its aggressive nature, high recurrence rates, and resistance to standard treatment approaches. Unfortunately, only a limited number of clinical trials specifically focus on this distinct cancer subtype ⁶. Further research is essential to better understand its origin, imaging characteristics, and potential therapeutic strategies to improve patient outcomes.

Conclusion

Our knowledge of MBC is still very limited, and MBC patients are not sufficiently included in clinical studies. There is a need for international studies and data to be increased to regulate the treatment of patients and improve survival rates. Although the diagnosis of MBC can be difficult in every respect, early diagnosis is critical in the management of patients.

Declarations

References

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About This Article

Received:

March 28, 2025

Accepted:

July 3, 2025

Published Online:

July 11, 2025