ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 ER-negative, 42 ER-positive, 21 PR-negative, 33 PR-positive, 47 HER2-negative and 7 HER2-positive carcinomas. No difference was found between receptor-negative and receptor-positive cases with respect to ER and PR for both KISS1 and KISS1R and with respect to HER2 for KISS1, however KISS1R expression levels were significantly higher in HER2-negative compared to HER2- positive carcinomas. Conclusion: Software-based assessment of immunostaining is a more objective way of quantifying staining intensity when study- ing potential new markers for which no standardized assessment systems are developed. Taking into account receptor status is important when studying the altered function of KISS1/KISS1R system in the context of breast carcinomas. Higher expression of KISS1R in HER 2-negative carcinomas might indicate an alterna- tive pathway for stimulating proliferation of tumour cells when HER2 expression is low. Funding: This work was supported by grant No KП-06-M31/5 of the Bulgarian National Science Fund - Ministry of Education and Science of Bulgaria E-PS-02-020 Primary neuroendocrine breast carcinoma or metastatic lung cancer? The role of a careful interpretation of GATA-3 J. Caschili*, A. Ravarino, L. Nonnis, R. Murru, C. Gerosa, G. Faa, D. Fanni *Department of Medical Sciences and Public Health, University of Cagliari, Italy Background & objectives: Primary small cell neuroendocrine carci- nomas (SCNECs) of the breast are extremely rare. Here we report the case of a 61-year-old woman with a palpable mass developed in the upper-outer quadrant of the left breast. Methods: Biopsy specimens were fixed in 10% formalin and paraf- fin embedded. Serial sections were stained with H&E. Histology revealed a pattern compatible with infiltrating small cell neuroen- docrine carcinoma of the breast. Immunohistochemical analyses were performed using the following antibodies: Cytokeratin AE1/ AE3, p63, GATA-3, Cytokeratin 7, Cytokeratin 20, Chromogranin A, Synaptophysin, CD 56, Estrogen Receptor, Progesteron Recep- tor, Her2-neu and TTF-1. Results: Microscopically, tumour cells were arranged in solid nests and cords with nuclear pleomorphism, high nuclear-cytoplasmatic ratio and scattered areas of intratumoural necrosis. Immunohisto- chemical analyses revealed negativity for Cytokeratin 20, Chro- mogranin A, Estrogen and Progesterone Receptors, HER2-NEU and p63. Cytokeratin AE1/AE3, Cytokeratin 7 and the neuroen- docrine markers CD 56 and Synaptophysin were positive. TTF-1 was strongly positive and GATA-3 was focally positive. On these bases the diagnosis of primary small cell neuroendocrine carci- noma (SCNEC) of the breast was made. Conclusion: The tumour here described showed a strong and dif- fuse positivity to TTF-1 in the absence of ductal carcinoma in situ or areas of conventional-type mammary carcinoma. Thanks to the presence of a positive, albeit focal, GATA-3 stain of the tumour cells, it was possible to make a diagnosis of primary small cell neu- roendocrine carcinoma (SCNEC) of the breast. Our diagnosis was subsequently confirmed by a PET-scan performed by the patient in another facility. E-PS-02-021 Challenging diagnosis in breast undifferentiated sarcoma - a case report F. Almarii*, A. Blajin, D. Terzea, L. Welt, G. Lica, G. Halcu, I. Popa *Emergency University Hospital, Romania Background & objectives: Primary breast sarcomas are rare entities with aggressive behaviour and poor prognosis. Undifferentiated pleo- morphic sarcoma is even rarer in non-irradiated patients. It is important to corelate the clinical features, histology and immunohistochemistry in order to make this diagnosis. Methods: We present the case of a 36-year-old woman who pre- sented in January 2022 to our clinic because of a fast growing, giant tumour of the right breast. Mammography showed a 23 cm nodule with increased radio-intensity and with homogenous tex- ture, occupying almost the entire breast. Results: A core needle biopsy was performed and it showed a mesenchymal proliferation with desmin(+) and vimentin(+), focal positivity for actin, caldesmon, cytokeratin and ki-67 30%, sug- gestive of a Phyllodes tumour without the epithelial component on biopsy or a sarcoma. The right mastectomy showed a multinodular, relatively well- delineated, non-encapsulated tumour. On cut surface there was a heterogenous lesion with solid, cystic or translucid areas with extensive necrosis and haemorrhage and a thin rim of breast tissue at the periphery of 0.5cm. Histology showed a proliferation of spindle and epithelioid cells with a storiform pattern, frequent giant cells, marked pleomor- phism, areas of tumour necrosis and frequent mitotic figures. No leaf-like epithelial pattern. Conclusion: This case was signed out as a right breast undifferentiated pleomorphic sarcoma, grade 3 FNCLCC, pT4, and immunohistochemistry was recommended for confirmation. Primary undifferentiated pleomorphic sarcoma of the breast is a rare entity with an aggressive behaviour. This case shows the clas- sic clinical features of a breast sarcoma as a fast-growing giant tumour with interesting morphologic features. Immunohistochem- istry is very important to differentiate it from other sarcomas, meta- plastic breast carcinoma or from a malignant phyllodes tumour. E-PS-02-022 Incidental invasive lobular carcinoma arising in a fibroepithe- lial lesion L. Williams*, A. Arnaout *St George’s Hospital, London, United Kingdom Background & objectives: Malignant transformation of the epithelial component of fibroepithelial lesions is rare, and when identified, is most often either an in-situ malignancy or invasive ductal carcinoma. We report an exceedingly rare case of invasive lobular carcinoma, dis- covered in a fibroepithelial lesion. Methods: A 41-year-old patient presented to the breast clinic with a lump of 2 months duration. On examination this was felt to be benign, however mammogram and ultrasound were performed and the decision was made to excise the lesion. Results: Microscopically the lesion was a well-circumscribed multi- nodular tumour, composed of some areas resembling a fibroadenoma, but with other areas displaying mild stromal hypercellularity, periductal condensation and nuclear pleomorphism. The tumour was mitotically low, and appearances were consistent with a borderline phyllodes. Within the lesion, however, individual atypical cells were noted, dis- playing mild nuclear pleomorphism and prominent nucleoli. Immu- nohistochemistry revealed these atypical cells to express AE 1/3 and ER but to be negative for e-cadherin and CK5. The appearances were consistent with a focus of classical grade 2 invasive lobular carcinoma S196