Metaplastic breast carcinomas (MBC) was first described by Huvos in 1973. They are rare tumors and account for approximately 0.25-1% of all breast malignancies. These tumors are histologically defined by the differentiation of the neoplastic epithelium into squamous or mesenchymal-like elements.According to the Who classification, low grade adenosquamous carcinoma ,fibromatosis like MBC,squamous cell carcinoma ,spindle cell carcinoma,MBC with mesenchymal differentiation (chondroid, osseous, and other types), and mixed type MBC are divided into subtypes. Clinically, it is manifested by a rapidly growing mass in the breast but axillary metastases are seen rarely. The average age is 55 years in some studies. There is high density mass in mammography, microcalcification is seen rarely in the presence of in situ component. 

Immunohistochemically, ER, PR and Cerb-b2 are generally negative. PIK3CA/PIK3R1 mutations and TP53 mutation are high in their genetic characteristics. TERT promoter mutation is also seen. Metaplastic breast carcinomas have a worse prognosis than other triple-negative breast carcinomas and higher risk of distant metastases. They often metastasize to the lungs and bones. In some species, the risk of local recurrence is higher. While mastectomy or breast-conserving surgery is applied in the treatment, mastectomy is generally more preferred due to the large diameter of the tumor. Radiotherapy and chemotherapy are used as adjuvant therapy, studies have shown that the benefit of neoadjuvant chemotherapy is generally low. Immunotherapy and smart drug therapies are also used.

Chemotherapy protocols are generally similar with other triple negative tumors. In some studies those who receive anti-HER-2 therapy have better survival than those who do not, for HER-2 positive MBC.

In high-risk,triple negative - stage 2-3 patients, preoperative pembrolizumab-carboplatin-paclitaxel+preoperative pembrolizumab-cyclophosphamide-doxorubicin+adjuvant pembrolizumab treatment options are available.

In our retrospective study from SBÜ. Ankara Oncology Training and Researche Hospital, there were 56 patients with MBC (June 2006-December 2016). The most common subtype was squamous cell (14.2%) MBC, the most common T stage was T2 (57.1%). Average age was 51.3. Average tumor diameter was 4 cm (1.3-16.6 ). Triple negativity was 67.8%. Axillary node positive patients rate was 44.6%, aksillary node negative patients rate was 41%. Median follow-up 45.8 months (4.9-130). 5 years OS rate was 67%, DFS rate was 64%. Local recurrence was seen in 4 patients (7.1%) .Distant metastases rate was 26.7%.

In our study, there was one patient with bilateral squamous cell MBC. Patient received radiotherapy and chemotherapy after operation for both side. Receptor was negative but Her- 2 was positive for right side tumor so patient also received anti Her 2 therapy for right side .Triple negative for left side tumor. After 7 months of left side breast tumor lung metastasis was developed. Receptor was negative but Her 2 was positive on pleural fluid cytology. 6 cycles vinorelbine, trastuzumab chemotherapy was applied to patient and  overall survival was 34 months in this patient. 

To be Updated.