No Special Type İnvasive Breast Carcinoma Transformed To MetaplasticCarcinoma After Neoadjuvant Chemotherapy

31th European Congress of Pathology, Nice, Fransa, 7 - 11 Eylül 2019, cilt.31, ss.16

No special type invasive breast carcinoma transformed to metaplastic carcinoma after neoadjuvant chemotherapy G. Kir1 , Z.C. Olgun1 , O. Alimoglu2 1 Istanbul Medeniyet University, Department of Pathology, Turkey, 2 Istanbul Medeniyet University, Department of General Surgery, Turkey Background & Objectives: Metaplastic breast carcinoma is a rare and aggressive type of breast carcinoma. Here, we report a case of metaplastic breast carcinoma which transformed from Invasive Breast Carcinoma, No Special Type (NST) following neoadjuvant chemotherapy (NAC). Methods: 46 year-old woman presented with a palpable mass which was diagnosed with tru cut biopsy as invasive breast carcinoma, NST. The patient received 4 cycles of NAC with anthracyclin and taxane Results: The patient underwent a segmental mastectomy after NAC. Microscopically the tumour was arranged in a diffuse pattern. Tumour cells had large vesicular, irregular nuclei with prominent nucleoli and abundant cyoplasm. Necrosis was detected in large areas. The neoplastic cells of the excised tumour were estrogen receptor (ER), progesterone receptor (PR), and HER-2 negative whereas on previous biopsy tumour cells were diffusely positive for ER and PR and negative for HER-2. After NAC tumour showed diffuse positivity for EGFR and vimentin, scattered cells stained with P63 and HMWCK. EMA was patchy and weakly positive at neoplastic cells. Tumour was negative for PANCK, CAM 5.2, Cytokeratin 5/6, Cytokeratin 14, and CD34. So the tumour was consistent with metaplastic carcinoma. Conclusion: Immunhistochemical changes after NAC is not an uncommon finding but morphologic transformation is very rare entitiy. This is the third case of transformation to metaplastic carcinoma after NAC as far as we know from English literature.