Carcinosarcoma (CS), also known as metaplastic breast carcinoma with mesenchymal differentiation, is one of the five distinct subtypes of metaplastic breast cancer. It is considered as a mixed, biphasic neoplasm consisting of a carcinomatous component combined with a malignant nonepithelial element of mesenchymal origin without an intermediate transition zone. Although cellular origin of this neoplasm remains controversial, most researchers declare that neoplastic cells derive from a cellular structure with potential biphasic differentiation. Despite recent research on the therapeutic strategies against CS neoplastic disorders, surgical resection appears the only potentially curative approach. Since CS metastasize by the lymphatic route, axillary assessment with sentinel lymph node biopsy and/or axillary lymph node dissection is always implemented. Nevertheless, the tumor also presents a hematogenous metastatic pattern including pleural, pulmonary, liver, brain and less commonly bone metastases. Thus, surgical removal of breast CS does not necessarily ensure patient's long-term recovery. Moreover, alternative therapies, such as radio- and chemotherapy proved insufficient and 5-year survival rate is limited. Nevertheless, there is evidence that following surgery, the combination of radio and chemotherapy is associated with a better prognosis than either treatment alone. The aim of this review is to evaluate the results of surgical treatment for breast CS with special reference to the extent of its histological spread. Clinical features, histogenesis, morphological and immunochemical findings are discussed, while the role of current diagnostic and therapeutic management of this aggressive neoplasm is emphasized.

Metaplastic breast cancer (MBC) is a rare disease, and there was rarely reported the treatment after recurrence and metastasis. Here, we report the treatment of an adult patient who suffered from MBC with lung, lymph nodes and left pleura metastasis after radical surgery. The next-generation sequencing result demonstrated that it had tumor mutational burden (TMB) of 12.0 Muts/Mb and microsatellite stability. The patient received sintilimab, an immune checkpoint inhibitor, plus chemotherapy and achieved partial response (PR). This is a report of a good outcome of metastatic MBC achieving 24 months of progression-free survival (PFS) and 39 months of overall survival (OS) with a combination therapy of immune checkpoint inhibitor and chemotherapy. Immuno-chemotherapy may have antitumor activity for relapse MBC. TMB may serve as a potential predictor associated with PD-1 inhibitors in MBC and help clinicians make an optimum treatment strategy.

Carcinosarcoma of the breast is a rare disease. Its clinicopathological features and prognosis are not well defined. The aim of this study was to compare the clinicopathological features and clinical outcome between breast carcinosarcoma and breast invasive ductal carcinoma (IDC).

Patients with breast carcinosarcoma and breast IDC were identified through the Surveillance, Epidemiology, and End Results (SEER) database from 2010 to 2015. Then a comparison was conducted between these two groups. Propensity score matching (PSM) was performed to balance the effects of baseline clinicopathological differences. The Cox proportional hazard model was used to identify potential prognostic factors of breast carcinosarcoma.

In total, we identified 63 patients with breast carcinosarcoma and 200,596 cases with breast IDC. Comparing with IDC, breast carcinosarcoma was significantly correlated with higher grading, higher staging, larger tumor size, lower lymph node involvement, and a higher proportion of triple negative breast cancer (TNBC), suggesting a significantly worse clinical outcome. After adjusting for the uneven clinicopathological variables with PSM, significant differences were still observed between these two histology types. Subgroup analysis further showed that carcinosarcoma-TNBC has an inferior clinical outcome compared with IDC-TNBC. Finally, we identified independent prognostic factors, namely, stage, tumor size, and distant metastasis.

It is concluded that breast carcinosarcoma has distinct clinicopathological features and a significantly worse clinical outcome than common IDC.

A neutered female domestic shorthaired cat was presented for a rapidly growing left cervical mass and a 6-month history of primary hyperthyroidism. Cytological examination of the mass was consistent with a sarcoma. Due to poor clinical response the cat was humanely destroyed and a post-mortem examination was performed. This revealed a markedly enlarged, irregularly shaped left thyroid gland with signs of infiltration of the trachea. The contralateral (right) thyroid was also moderately enlarged and irregularly shaped. Histopathological examination of the cervical masses indicated bilateral thyroid carcinosarcomas, evidenced by positive immunohistochemical labelling for vimentin, pan-cytokeratin and thyroid transcription factor-1 of the appropriate cell populations. The cat also had a concurrent pulmonary adenocarcinoma (papillary-lepidic type), unrelated to the thyroid neoplasm. Thyroid carcinosarcoma is an uncommonly recorded canine and human neoplasm and this is the first case of this entity to be reported in a cat.

Metaplastic carcinoma of the breast with mesenchymal differentiation (MCMD), previously known as carcinosarcoma, is a very rare and aggressive tumor that has been recently classified as a subtype of metaplastic breast carcinoma. It accounts for 0.08%-0.2% of all breast cancers, with only a few cases reported in the literature. Histologically, MCMD is characterized by a biphasic pattern of malignant epithelial and sarcomatous components without evidence of a transition zone between the two elements. We herein describe a unique case of metaplastic carcinoma of the breast with chondrosarcomatous differentiation in a postmenopausal woman who presented with a large, rapidly growing, ulcerated, bleeding mass and signs of impending sepsis. Metaplastic breast carcinomas (MBC) are rare and aggressive tumors. They are characterized by larger size, lower rates of axillary node involvement, higher rates of triple negativity and distal metastases, earlier local recurrence and poorer survival compared with classic invasive breast cancer. Because of the rarity of MBC, the optimal treatment has not been well defined. Surgery is the main curative treatment modality since MBC has shown a suboptimal response to standard chemotherapy. Patients with MBC may be appropriate candidates for novel targeted therapies.