Metaplastic Breast Cancer (MpBC) is an exceedingly rare entity, accounting for less than 1% of all malignant breast tumours. Predominantly triple-negative, they are notorious for their chemoresistance, high rates of recurrence and decreased disease-free survival (DFS). All this contributes significantly to BC mortality and results in poor prognostic implications. Limited evidence has led to a lacuna of specific treatment guidelines for this entity and hence remains an uncharted territory for clinicians.
We report a case of a 46 year old premenopausal female with left-sided metaplastic triple negative T3N2aM0 BC with mesenchymal differentiation (high grade) whom we treated with neoadjuvant chemotherapy, primary surgery in the form of extreme oncoplasty and adjuvant radiotherapy by Telecobalt machine. Contrary to the expected aggressive course of the disease and poor prognosis of treatment, the patient is presently in remission without progression for over 2 years of follow up.
Limited experience in management of this pathological entity warrants the need for more research on it, with a special focus on targeted therapy. Discussing possibilities of a tailored approach, rather than a one-size-fits-all approach may aid in paving the path for the future of MpBC treatment.

Continuous low-dose 5-FU was popularized as a therapy for pretreated metastatic breast cancer for the past few decades, spurred by the advent of the electronic infusion pump. Capecitabine, otherwise known by its trade name Xeloda, is a prodrug of 5-fluorouracil (5-FU), which is administered orally in many chemotherapy regimens, and plays a role in metastatic breast cancer treatment refractory to traditional anthracyclines and taxane therapy. In this case presentation, we describe a unique case of refractory de-novo stage IV triple-negative breast cancer presented with right breast primary invasive ductal carcinoma, extensive lymphadenopathy, with biopsy proven bone marrow infiltration, diffuse hepatomegaly, splenomegaly, significant hyperbilirubinemia, and bone marrow failure treated with continuous 5-FU infusion and subsequently oral capecitabine after initial treatment failure with nab-paclitaxel and sacituzimab govitecan. With this case presentation, the authors aim to showcase the versatility of 5-FU and its prodrug in treatment of metastatic triple-negative breast cancer with severe bone marrow and liver involvement while highlighting key physiologic and pharmacologic mechanisms.

Metaplastic breast carcinoma is rare and may present as a highly aggressive subtype of breast cancer. In this case report of metastatic metaplastic breast carcinoma with osteosarcomatous differentiation in a female patient previously treated for invasive ductal carcinoma, we describe the new presentation of a palpable mass with associated calcifications on imaging near the site of prior partial mastectomy. This article will detail the clinical presentation, imaging findings, histopathology, and clinical course following treatment of our case. Knowledge of the clinical and imaging presentation of this rare subtype, which can present with benign features on mammography and ultrasound, can facilitate timely diagnosis as treatment paradigms evolve.

UNASSIGNED: Matrix-producing carcinoma (MPC) is a rare tumor accounting for 0.1% of all breast cancers. Although MPC is usually triple-negative breast cancer, there have been few reports of preoperative chemotherapy for MPC that is considered chemotherapy-resistant. Herein, we report a case of MPC that was successfully treated with preoperative chemotherapy.
UNASSIGNED: The patient was a 47-year-old woman diagnosed with right multiple breast cancer, clinical stage IIA. One of the tumors was identified as MPC and the other was invasive ductal carcinoma. The maximum tumor diameter of MPC was 3.8-cm. On immunohistochemistry, the tumor cells of MPC tested negative for estrogen receptor (ER), progesterone receptor (PgR), and human epidermal growth factor receptor 2 (HER2). The Ki67 index was 90%. Preoperative chemotherapy was performed. EC (epirubicin 90 mg/m2 and cyclophosphamide 600 mg/m2) was administered every 3 weeks for a total of 4 courses, followed by 12 courses of weekly paclitaxel (80 mg/m2). Then, she underwent right skin-sparing mastectomy, sentinel lymph node biopsy, and deep inferior epigastric perforator flap reconstruction. There was no metastasis to the sentinel lymph nodes. Postoperative pathological results showed that the residual tumor of the MPC measured only 0.1 cm. On the other hand, the residual tumor of the invasive ductal carcinoma was 0.7 cm. Endocrine therapy with oral tamoxifen was initiated for the invasive ductal carcinoma. Three years after surgery, no recurrence was observed. It has been reported that prognosis was correlated with residual cancer after preoperative chemotherapy. In addition, preoperative chemotherapy is of high clinical significance for the selection of postoperative treatment.
UNASSIGNED: Although our case of MPC was successfully treated with preoperative chemotherapy, the standard of care for MPC remains uncertain. Development of a new targeted therapy for MPC is warranted.

Microglandular adenosis is a non-lobulocentric haphazard proliferation of small round glands composed of a single layer of flat to cuboidal epithelial cells. The glandular structures lack a myoepithelial layer; however, they are surrounded by a basement membrane. Its clinical course is benign, when it is not associated with invasive carcinoma. In around 30% of cases, there is a gradual transition to atypical microglandular adenosis, carcinoma in situ, and invasive breast carcinoma of several different histologic subtypes, including an invasive carcinoma of no special type, metaplastic matrix-producing carcinoma, secretory carcinoma, metaplastic carcinoma with squamous differentiation, acinic cell carcinoma, spindle cell carcinoma, and adenoid cystic carcinoma. Recent molecular studies suggest that microglandular adenosis is a non-obligate precursor of triple-negative breast carcinomas. In this manuscript, we present a unique case of microglandular adenosis associated with metaplastic matrix-producing carcinoma and HER-2 neu oncoprotein positive pleomorphic lobular carcinoma in situ with apocrine differentiation in a 79-year-old patient.

Essential thrombocythemia is one of the famous diseases under the category of myeloproliferative disorder. It is an end result of a genetic mutation of one or more of the most frequent oncogenes such as Janos kinase 2 (JAK2), MPL proto-oncogene, thrombopoietin receptor (MPL), and calreticulin (CALR). However, negative genetic markers, so-called (triple negative disease), can happen in the presence of other uncommon types of mutation. TET2 (ten-eleven translocation 2) positive as isolated genetic marker in triple negative essential thrombocythemia is uncommon genetic presentation. For that, we are reporting a 22-year-old lady who presented with a feature of dyspepsia and accidentally found to have persistently high platelet count, even after treating her mild iron deficiency anemia with no other secondary causes. Further investigations and bone marrow biopsy supported the diagnosis of isolated TET2 positive in triple negative essential thrombocythemia. We treated her conservatively with good hydration and low dose of aspirin. In conclusion, isolated TET2 positive in triple negative essential thrombocythemia at presentation is uncommon with no clear management or risk stratification guideline. However, it is hypothesized that TET2 mutation precedes JAK2; therefore, the detection of isolated TET2 in a triple negative essential thrombocythemia case should be closely followed for clonal evolution in long term. Further study and guidelines required in this area.

Rechallenge of immune checkpoint inhibitors has been reported for neoplasms other than breast cancer. Reported here is a case of a 55-year old woman diagnosed as having triple-negative right breast cancer with multiple metastases including lung. Atezolizumab and nab-paclitaxel were administered followed by epirubicin-cyclophosphamide. With subsequent eribulin, the overall best response was progressive disease, and curative surgical resection was performed. Three months after surgery (1.5 years after initial response of lung metastasis), right lung metastasis emerged at a site different from baseline. Based on the microsatellite instability-high status, pembrolizumab was administered and showed a good response. The patient has been treated with pembrolizumab, maintaining partial response, for over 9 months, which suggests the benefit of immune checkpoint inhibitors rechallenge in breast cancer.

Carcinosarcoma, also known as metaplastic carcinoma, is a rare and aggressive malignant tumor. We report a case of metaplastic carcinoma presenting as inflammatory carcinoma and provide a review of the related literature. A 38-year-old breastfeeding woman presented with concerns about a painful lump in her left breast. The symptoms had been present for two months. After admission to the hospital, the triple assessment revealed findings consistent with inflammatory carcinoma of the breast. The patient underwent modified radical mastectomy. Histopathological examination revealed a gray-white tumor with a biphasic pattern with features of ductal carcinoma as well as squamous and sarcomatous differentiation. On immunohistochemistry, the neoplastic cells were positive for cytokeratin and vimentin, and focally positive for smooth muscle antigen (SMA) and negative for estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor (HER-2/neu). Based on histological and immunohistochemical findings, the tumor was diagnosed as carcinosarcoma. Four of eighteen dissected axillary lymph nodes were positive for metastasis. Carcinosarcoma is often a triple-negative tumor. The lack of standardized treatment protocols frequently leads to poor prognosis and can pose a diagnostic dilemma; it should be part of the differential diagnosis for a case of carcinoma of the breast presenting as inflammatory carcinoma.

OBJECTIVE: Breast cancer (BC) risk factors have been differentially associated with BC subtypes, but quantification is still undefined. Therefore, we compared selected risk factors with BC subtypes, using a case-case approach.
METHODS: We retrieved 1321 invasive female BCs from the Piedmont Cancer Registry. Through record linkage of clinical records, we obtained data on estrogen (Er) and progesterone (Pr) receptors, Ki67 and HER2+ status, BC family history, breast imaging reporting and data system (BI-RADS) density, reproductive risk factors and education. We defined BC subtypes as follows : luminal A (Er+ and/or Pr+ , HER2- , low Ki67), luminal BH- (Er+ and/or Pr + , HER2- , Ki67 high), luminal BH+ (Er+ and/or Pr + , HER2+), HER2+ (Er - , Pr - , HER2+), ) and triple negative (Er - , Pr - , HER2-). Using a multinomial regression model, we estimated the odds ratios (ORs) for selected BC risk factors considering luminal A as reference.
RESULTS: For triple negative, the OR for BC family history was 1.83 (95% confidence interval (CI) 1.13-2.97). Compared to BI-RADS 1, for triple negative, the OR for BI-RADS 2 was 0.56 (95% CI 0.27-1.14) and for BI-RADS 3-4 was 0.37 (95% CI 0.15-0.88); for luminal BH +, the OR for BI-RADS 2 was 2.36 (95% CI 1.08-5.11). For triple negative, the OR for high education was 1.78 (95% CI 1.03-3.07), and for late menarche, the OR was 1.69 (95% CI 1.02-2.81). For luminal BH + , the OR for parous women was 0.56 (95% CI 0.34-0.92).
CONCLUSIONS: This study supported BC etiologic heterogeneity across subtypes, particularly for triple negative.

BACKGROUND: Breast cancer arising from benign fibroadenoma (FA) is rare. The histological type of the former was either carcinoma in situ or early-stage invasive breast carcinoma with hormone receptor positive/HER2 (human epidermal growth factor receptor-2)-negative phenotype. Meanwhile, advanced breast cancer of triple negative (TN) phenotype such as our case is extremely uncommon and clinically challenging.
METHODS: We experienced a case of a 53-year-old woman that had invasive ductal carcinoma of TN phenotype in FA with multiple lymph node metastases. After receiving neoadjuvant chemotherapy (NAC), she underwent breast mastectomy and axillary dissection. The pathological examination on postoperative specimens revealed the dense fibrous stroma in the FA without any residual viable tumor cells and was considered as pathological complete response (pCR).
CONCLUSIONS: This is the first report presenting a case of NAC treatment for invasive ductal carcinoma (IDC) in FA. Furthermore, the patient achieved pCR even if IDC was located within FA. Diagnosing breast cancer in FA may be challenging as the carcinoma component may be hidden by the FA component. If imaging of FA became larger or abnormal changes during follow-up examinations, needle biopsy should be recommended for assessment of the lesion positively.
CONCLUSIONS: This is the first report presenting a case of advanced breast cancer in FA of TN phenotype with multiple lymph node metastases who achieved pCR even if IDC was located within FA.