ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 Results: A new core biopsy was performed revealing an extra- pleural solitary fibrous tumour (CD34+, STAT6 +) with features suspicious of malignancy (EWGBP-B4).The patient was submit- ted to total mastectomy and partial excision of the pectoralis muscle, and the histological diagnosis was a breast malignant solitary fibrous tumour. According to Demicco et al’s refined stratification model, this case fitted into the high risk class for distant metastasis. Despite a suboptimal excision margin, consid- ering patient performance status, the sarcoma’s multidisciplinary team proposed local and systemic vigilance. Four months later, clinical status quickly deteriorated, liver and lung metastization was detected, and the patient died within a month. Conclusion: SFT has an indolent course with relatively infrequent metastasis (5-25%), aside those cases with sarcomatous transfor- mation. There are few cases of breast SFT and most of them are benign and limited to the female gender. This is the third case of a breast malignant SFT so far and in this case with a fatal outcome. E-PS-02-006 Metaplastic breast carcinoma: a case report G. Crilly*, N. Shah *University Hospital Waterford, Ireland Background & objectives: Metaplastic breast carcinoma is a morphologically diverse cancer type which shows differentiation of malignant epithelium into squamous or mesenchymal elements and accounts for 1% of breast cancers. The mesenchymal elements are usually composed of osteoid, chondroid and areas of carcinoma. Methods: We present the case of an 84 year old lady present- ing with a rapidly enlarging left breast mass over 6 months. Past medical history was significant for ischaemic heart disease. A wide local excision revealed a 60mm, calcified lesion. Results: This was a well-circumscribed tumour composed of atypical mononuclear epithelioid and spindled cells. There were areas of bone and cartilage formation with osteoclast-like giant cells. There were focal areas of malignant squamous and chondroid differentiation. Mitotic activity and necrosis was noted. The atypical epithelial cells were strongly positive for AE1/3, p63, and focally positive for CK5/6 and SMA. They were negative for CD34, desmin, EMA, ER, PR, Her2, GATA3, LCA and S100. SATB2 was positive in the malignant osteoid component. As such, this lady was diagnosed with a metaplastic carcinoma with osteosarcomatous differentiation. Conclusion: Metaplastic breast carcinoma is a rare malignancy and thorough sampling is crucial. When mesenchymal elements are present, the other main differentials are a primary breast osteo- sarcoma and malignant phyllodes tumour. Metaplastic carcinoma will stain for cytokeratins. Staging is dependent on tumour size as per the UICC/ATCC 8th editions. Diagnosis depends on the degree of heterologous elements present – those with a bland spindled morphology often do well while those with mesenchymal differ- entiation tend to be aggressive. E-PS-02-007 Tall cell carcinoma with reversed polarity of the breast I. Saguem*, W. Ben Makhlouf, S. Makni, M. Triki, C. Kammoun, T. Boudawara, S. Charfi, M. Mellouli *Department of Pathology, Habib Bourguiba University Hospital, Sfax, Tunisia Background & objectives: Tall cell carcinoma with reverse polarity (TCCRP) is an uncommon breast carcinoma, recently recognized as a separate entity in the 5th edition of the WHO classification of breast tumours. Herein, we report the first case of TCCRP in South Tunisia. Methods: We report a case of a 34-year-old woman diagnosed with TCCRP and we review histological and immunohistochemical features of this rare entity. Results: Our patient presented with a palpable mass located in the superomedial quadrant of the right breast. Echomammography revealed an atypical mass classified ACR4a. The trucut biopsy specimen reported an atypical papillary proliferation. The patient underwent lumpectomy. Histological examination showed circum- scribed nests of epithelial cells with delicate fibrovascular cores resembling papillary structures. Fibrovascular cores contained sometimes foamy histiocytes and were lined by columnar cells with abundant eosinophilic cytoplasm and apical nuclei showing some grooves. On immunohistochemistry, tumour cells were diffusely positive for CK5/6, Calretinin and were negative for oestrogen, progesterone, HER-2, TTF1, and p63 (this antibody indicated the absence of myoepithelial cells within and around the nests). Conclusion: Few cases of TCCRP have been reported in the literature. It resembles tall cell variant of papillary thyroid carcinoma but has a distinct morphological, immunohistochemical, and molecular profile (IDH2 mutation). Its pathological diagnosis can be challenging and difficult to establish. The treatment is mainly based on surgery. No clear indications exist for lymph node dissection, radiotherapy, and chemotherapy. TCCRP has an excellent prognosis with low metastatic potential. E-PS-02-008 Digital radiography for histopathologic examination of breast cancer after neoadjuvant chemotherapy I. Telezhnikova*, L. Zhukova, S. Khomeriki, G. Setdikova *Loginov Moscow Clinical Research Center, Russia Background & objectives: Pathologists have various and difficult problems related to sampling for histologic examination specimens of breast cancer after neoadjuvant chemotherapy. The aim of this study was to optimize the pathologic assessment for residual disease in breast cancer after neoadjuvant chemotherapy. Methods: The analysis were patients who underwent radical surgi- cal treatment for invasive carcinoma of the breast after neoadjuvant chemotherapy. All patients had a good clinical response to treat- ment. It was performed using a pathology specimen digital radiog- raphy the Faxitron® Path system (digital X-ray). Specimens radi- ography reports were compared to the histopathologic evaluation. Results: The study comprised 32 subjects, average age of the patients was 52.5 (9.4). Macroscopic assessment of the primary tumour was not probable, the tumour bed was not palpable. Accuracy of macroscopic determination of calcinates in relation to digital radiography was 93.8% (79.2–99.2). Tumour bed sizes determined macroscopically (mean maximal size 6.1 (3.3) cm, median 5.2 (3.4–8.0) cm) and using digital X-ray (mean maximal size 4.8 (2.6) cm, median 4.1 (2.7–6.2) cm) had statistically significant differences (p < 0.0001). In most cases (31/32 (96.9%)), clear dimensions of the tumour bed were determined by digital X-ray, whereas macroscopy in 25/32 (78.1%) cases determined fuzzy dimensions (p < 0.0001). Conclusion: Using digital X-ray facilitated the morphological identification of metal markers implanted into the tumour bed, microcalcifications, altered foci, improved tumour bed visibility, which is important for further objective status assessment of the resection margins and residual cancer burden class. The number of repeated incisions decreased which reduced the number of his- tological cassettes and study time. Without specimen radiography, important pathological areas may be easily missed. The results S192