ECP 2023 Abstracts

S189 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 Results: Histologic examination showed skin infiltrated by a neoplasia characterized by nodules of intermediate-sized cells with scant cyto- plasm and vesicular and irregular nuclei sometimes with prominent nucleoli. These nodules were arranged predominantly around the adnexa, vessels, and hypodermis. There were frequent mitotic figures and extravasated red blood cells and no epidermotropism. Immuno- histochemistry revealed expression of CD4, CD56, Bcl2 and CD123 in the neoplastic cells with no expression of CD20, CD3, CD2, CD5, CD7, CD8, CD10, Bcl6, MUM1, CD21, CD23, Cyclin D1, TdT, CD30, Perforin, Granzyme, TIA1, Myeloperoxidase and CD68. Chromogenic in situ hybridization (CISH) for the detection of Epstein-Barr virus- encoded RNA (EBER) was negative. Conclusion: The diagnosis of BPDCN requires, along with morpho- logic features, immunohistochemistry that demonstrates CD4, CD56, CD123, CD303 and TCL1 expression, together with lack of expres- sion of B, T, myeloid or monocytic, and NK cells. The disease usually progresses rapidly with leukemic spread and multiorgan involvement and therefore the prognosis is poor, with a median overall survival ranging from 9 to 20 months. The patient is currently alive 9 months after the diagnosis. E-PS-05-038 From basic to the never-ending story of melanoma and its rhabdoid variant – a case report A.H. Sabau*, I.G. Cocuz, M.C. Popelea, A.C. Tinca, O.S. Cotoi *UMFST Targu Mures, Romania Background & objectives: It is well known that melanoma can present a multitude of variants from a cytopathological point of view. Rhab- doid melanoma is an extremely rare variant characterized by nests of polygonal cells, with abundant cytoplasm and vesicular nuclei with prominent nucleoli. Methods: We present the case of an 82-year-old female who presented with a nodule on her back. Surgical resection was performed, and the spec- imen was sent to the pathology department for histopathological diagnosis. Results: Microscopic examination revealed an ulcerated nodule with a maximum size of 10 mm, composed of two distinct cell populations. The predominant cell population was composed rhabdoid tumour cells, polygonal in shape, with abundant eosinophilic cytoplasm and vesicular nuclei. The second population was located peripherally and was composed of epithelioid cells. 44 mitoses / 10 HPF were identified in the rhabdoid cell population. Melanic pigment was identified only in the epithelioid population. Immunohistochemistry studies showed heterogeneity, rhabdoid type cells being positive for SOX10, while the epithelioid type cells being positive for SOX10, Melan A and HMB45. Conclusion: The histopathological appearance and the immunohis- tochemically profile led to the diagnosis of rhabdoid melanoma. The clue for diagnosis is based on the immunohistochemically mirror appearance, were Melan A and HMB45 are negative for the rhabdoid cell population and positive for the epithelioid one. Identifying and differentiating this type of melanoma represents a big challenge, as most of the previously reported cases described the rhabdoid type in recurrences or metastases. E-PS-05-039 Healthy woman with active 15cm rib ulcer that does not heal: what is happening? A. Sanz Zorrilla*, I. Sánchez Ramírez, J. Osuna Soto, S. Haro Yuste, F. Leiva-Cepas *Hospital Universitario Reina Sofía, Spain Background & objectives: We are used to seeing chronic wounds or torpid ulcers that do not heal in elderly patients. However, approxi- mately 90% of these cases are usually located in extremities, we want to describe one unusual case that internists did not believe. Methods: We present a case of a 60-year-old woman who had one of her left ribs broken by a trauma one year ago. 5 months later, she developed an ulcer in the same location, which progressively became larger. An ultrasound was performed, and it was treated as an infectious wound. A biopsy was performed to rule out Pyoderma gangrenosum. Results: A skin punch with an irregular surface of 5mm in diameter was performed. It was studied under light microscopy, and it presented a dense, perivascular and diffuse infiltrate with infiltrative growth that was dissecting muscle and collagen bundles, with necrosis and perineu- ral involvement. Tumour cellularity was large, irregular, pleomorphic with multiple nucleoli, and abundant mitotic figures. With immunohis- tochemical techniques, it was observed that they expressed: CD20+, PAX5+, CD30 (focal), EBER-, CD10-, BLC6+, MUM1- and cMYC+. The proliferative rate with ki67 was high. Abundant accompanying T cells were also observed, with involvement of the vascular wall and epi- dermotropism. Cells were TCRBF1 positive, and they did not express EBV (EBER) or CD30. Conclusion: In this case, the question arose with a malignant mes- enchymal neoplastic infiltration, although the definitive diagnosis was diffuse large B cell lymphoma of the germinal type, it could not be classified into any specific type because all the specific markers done were negative. A subsequent CT scan was performed, which showed retroperitoneal large lymph nodes, we have to rule out whether we are dealing with a primary skin lesion or a systemic process. E-PS-05-040 Cutaneous Langerhans cell sarcoma of the lip: a case report of a rare entity M. Slevin*, R. Williams *Dorevitch Pathology, Australia Background & objectives: Langerhans cell sarcoma is an extremely rare haematolymphoid neoplasm of dendritic lineage displaying aggressive clinical behaviour and frequent multisystem involvement. We present a case of primary cutaneous Langerhans cell sarcoma aris- ing on the lip of a 67-year-old man. Methods: The patient presented with what was clinically suspected to be squamous cell carcinoma of the lower lip and underwent exci- sion. No history of myeloid neoplasia was reported. Routinely prepared H&E stained sections of the excised tissue were examined and, after initial assessment, immunohistochemical inves- tigations performed. Results: Microscopically the biopsy showed a nodular superficial infiltrate with central epidermal ulceration and necrosis. Infiltrate comprised large epithelioid cells with ovoid, irregular nuclei and prominent amphophilic nucleoli extending into the deep dermis. Scattered folded nuclei with longitudinal nuclear grooves were seen. Mitotic activity, including atypical figures, was prominent. There was an intralesional lymphoplasmacytic and eosinophilic infiltrate. Tumour cells stained immunoreactive for CD1a, S100, CD31 and CD56. Langerin, cytokeratins, Sox-10, p40 and BRAF were negative. Ki67 index was >80%. This case was treated surgically and appeared completely excised ini- tially. Local recurrence occurred 11 months later and showed similar morphological and immunohistochemical findings on re-excision. Conclusion: In contrast to its benign counterpart, Langerhans cell sar- coma displays overt malignant cytology and ulceration and follows an aggressive clinical course. CD56 expression reportedly confers a worse prognosis. Inconsistent Langerin expression has been reported previously. Occurring primarily in adults and frequently in association with other haematological disorders, reported overall 5-year survival is less than 30%. Localised resectable cutaneous tumours have a more favourable prognosis. Due to its rarity, pathogenesis is poorly understood, and empirical mul- timodality treatment response is unpredictable.