Clinicopathologic characteristics of HER2-positive metaplastic squamous cell carcinoma of the breast

Better Local Disease Control With Mastectomy in Metaplastic Breast Carcinoma: Findings of a Retrospective Cohort

BACKGROUND

Metaplastic breast cancer (MBC) is a rare type of breast carcinoma with clinicopathological differences. The prognosis and treatment strategies for MBC are usually conflicting. In this study, we aim to present the clinicopathologic features, treatment strategies, and prognosis of our MBC patients.

MATERIAL AND METHODS

In our retrospective study, 18 metaplastic breast cancer patients treated in our institution between January 2005 and December 2022 were evaluated. Demographic and clinicopathological characteristics, surgical and systemic treatment options, locoregional recurrences, distant metastases, and overall survival (OS) of the MBC patients were retrieved from the patient files.

RESULTS

All patients were female; the median age was 54.42 ± 12.37 years. Most of the patients (n = 15, 83.33%) presented with palpable masses. Tumors were mostly triple-negative, with a high grade and a high Ki‑67 proliferation index. Spindle cell carcinoma and MBC with mesenchymal differentiation were the most common subtypes. Most of the patients underwent mastectomy (n = 11, 61.11%); breast-conserving surgery (BCS) was performed on seven (38,88%) patients. Lymph node positivity was detected in six of 18 patients (33.33%). Fewer patients (n = 4, 22.22%) received neoadjuvant chemotherapy. While local recurrence developed in two out of seven patients (28.57%) who underwent BCS, there was no local recurrence in patients who had mastectomy. The OS time varied according to tumor size and the presence of lymph node metastases (p <0.001; p = 0.005).

CONCLUSION

Metaplastic breast cancer is genetically heterogeneous and resistant to conventional treatment strategies. Mastectomy is still the surgical treatment method that is performed more frequently and provides better local control for patients with metaplastic breast cancer.

Primary squamous cell carcinoma of the breast: a case report

INTRODUCTION

Squamous cell carcinoma (SCC) of the breast is a rare variant of invasive breast cancer that has been classified as metaplastic carcinoma. When a tumor is composed of spindle cells, diagnosis is challenging.

CASE REPORT

A 42-year-old woman with a large mass in the right breast underwent modified radical mastectomy. A pathological examination revealed a tumor with central necrosis in it. The tumor had a sarcomatoid growth pattern and the cells were spindle-shaped with severe atypicality. Immunohistochemical staining showed that P63, P53, vimentin, and CKpan were positive, whereas estrogen receptor and C-erbB-2 were negative. Ki-67 proliferation index was as high as 90%. Therefore, a diagnosis of SCC of the right breast was made. The patient received eight cycles of postoperative chemotherapy with paclitaxel and carboplatin, followed by seven cycles of radiotherapy. During follow-up, the patient also had a left thyroid tumor, and postoperative pathology suggested microinvasive follicular carcinoma. Since breast surgery, the patient has remained disease-free for more than four years.

CONCLUSION

SCC of the breast with spindle cell and sarcomatoid features is rare. The diagnosis of such tumors requires exclusion of tumors with similar histological morphologies.

Case report: Successful treatment of a rare HER2-positive advanced breast squamous cell carcinoma

Background: Breast squamous cell carcinoma (SCC) is an uncommon and highly aggressive variant of metaplastic breast cancer. Despite its rarity, there is currently no consensus on treatment guidelines for this specific subtype. Previous studies have demonstrated that chemotherapy alone has limited efficacy in treating breast SCC. However, the potential for targeted therapy in combination with chemotherapy holds promise for future treatment options. Case presentation: In this case report, we present a patient with advanced HER2-positive breast SCC, exhibiting a prominent breast mass, localized ulcers, and metastases in the lungs and brain. Our treatment approach involved the administration of HER2-targeted drugs in conjunction with paclitaxel, resulting in a sustained control of tumor growth. Conclusion: This case represents a rare occurrence of HER2-positive breast SCC, with limited available data on the efficacy of previous HER2-targeted drugs in treating such patients. Our study presents the first application of HER2-targeted drugs in this particular case, offering novel therapeutic insights for future considerations. Additionally, it is imperative to conduct further investigations to assess the feasibility of treatment options in a larger cohort of patients.

The mixed subtype has a worse prognosis than other histological subtypes: a retrospective analysis of 217 patients with metaplastic breast cancer

OBJECTIVE

Metaplastic breast cancer (MpBC) is an aggressive subtype of all breast cancer. We aimed to investigate the clinicopathological features, treatments and prognoses of MpBC patients.

METHODS

We collected the data from MpBC patients diagnosed at Tianjin Medical University Cancer Hospital from 2010 to 2017. Kaplan Meier curves and Cox regression model were used to evaluating clinical outcomes and prognostic factors. After removing baseline differences by propensity score matching (PSM), we analyzed the prognosis between MpBC patients and invasive ductal carcinomas of no special type (IDC-NST) patients.

RESULTS

A total of 217 MpBC patients were subsumed. Of all histological subtypes, 45.1% were mixed subtypes, followed by with mesenchymal differentiation (27.2%), pure squamous (15.2%) and pure spindle (12.4%) subtypes. 69.6% of MpBC were triple-negative, 25.3% and 6.5% were HR-positive and HER2-positive. MpBC patients had worse survival compared to IDC-NST patients, with 5-year RFS of 73.8 and 83.6% (HR = 1.177 95%CI (1.171-2.676) P = 0.0068), and 5-year BCSS of 79.0% and 89.7% (HR = 2.187 95%CI (1.357-3.523) P = 0.0013). In the multivariate COX model, AJCC stage, mixed subtype and chemotherapy were independent prognostic factors. Mixed MpBC is more aggressive than pure and with heterologous mesenchymal differentiation subtypes. And whether squamous or spindle MpBC, mixed forms have shorter outcomes than pure forms.

CONCLUSIONS

MpBCs are associated with poorer prognoses than IDC-NSTs. They are heterogeneous with different clinicopathological features and clinical outcomes between histological subtypes. Pure and with heterologous mesenchymal differentiation subtypes have more survival benefits than the mixed subtype.

Metaplastic Breast Carcinoma Presenting as a Mixed Solid and Cystic Lesion

The objective of this paper is to report a rare presentation of metaplastic breast carcinoma (MBC) as a mixed solid/cystic mass and emphasize the possibility of having a different biopsy report and final diagnosis.

MBC is a rare type of breast cancer consisting of mesenchymal or mixed mesenchymal and epithelial components. It is believed to result from the conversion of glandular cells into non-glandular cells through various forms of mutations. It is common in females and more frequent in older women. MBC is a triple-negative breast cancer (progestin receptor, estrogen receptor, and human epidermal growth factor receptor 2) with a very poor prognosis when compared with other types of breast cancers.

This is a case of an 84-year-old woman presenting with rapidly growing mixed solid and cystic breast mass with a final diagnosis of MBC. The initial biopsy report was high-grade ductal carcinoma in situ. This is an unusual presentation of MBC.

Pathological Complete Response to Neoadjuvant Chemotherapy in a Patient with HER2-Positive Squamous Cell Carcinoma of the Breast

Squamous cell carcinoma (SCC) of the breast is a rare malignancy that usually has a triple-negative phenotype and poor clinical outcomes. Because HER2-positive SCC of the breast is extremely rare, its clinicopathologic features are understudied, and the effects of neoadjuvant chemotherapy including anti-HER2-targeted therapy on the tumor are unclear, although treatment resistance was described in some reports. In this study, we reported a case of HER2-positive SCC of the breast in which a pathological complete response to neoadjuvant chemotherapy was observed.

An Update on the Molecular Pathology of Metaplastic Breast Cancer

Metaplastic breast cancer (MpBC) is a fascinating morphologic sub-type of breast cancer, characterised by intra-tumoural heterogeneity. By definition, these tumors show regions of metaplasia that can present as spindle, squamous, chondroid or even osseous differentiation. MpBC are typically triple-negative, and are therefore not targetable with hormone therapy or anti-HER2 therapies, leaving only chemotherapeutics for management. MpBC are known for their aggressive course and poor response to chemotherapy. We review herein the pathology and molecular landscape of MpBC and discuss opportunities for targetted therapies as well as immunotherapies.