ECP 2023 Abstracts

S184 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 Results: A 74-year-old woman was referred to our centre due to extensive purpuric lesions centred on the lower limbs of one week of evolution that occupied 15% of the total body surface. During admission, she presented an excellent general condition with no clinical or analytical alterations (including hepatic and renal pro- files), except for a lengthening of the activated partial thromboplastin clotting time. Given the suspicion of APS, a skin biopsy and a bat- tery of antibodies were performed. The skin biopsy showed intravascular thrombi in small-vessels of the dermis and superficial subcutaneous tissue without associated inflam- mation. These findings, together with positive lupus anticoagulant antibodies, led to the diagnosis of APS. Conclusion: APS can manifest with very diverse skin alterations, including extensive necrosis. When present, it is usually accompanied by significant damage in different organs such as the kidney, lung or brain, due to microthrombi, with subsequent severe clinical picture called catasthrophic APS. However, as in our case, APS may be limited to extensive skin necrosis with no manifestations at other levels. E-PS-05-018 Consumption, discohesion, acantholysis and bullous changes. Malignant melanocytes ability that can affect diagnosis and prog- nostic parameters definition. How to manage such cases? A. Filosa*, F. Giantomassi, G. Cazzato, C. Rubini, G. Goteri *Polytechnic University of Marche Region, Pathological Anatomy Unit, Italy Background & objectives: Melanoma can present a variety of his- tological variants, many of which are exceedingly rare. Architectural variants displaying prominent discohesion include the more recently described bullous and acantholytic-like melanomas. Acantholytic/bul- lous changes in malignant melanoma have been rarely reported. Methods: We present two unique cases of malignant melanoma with varying degrees of extensive melanocytic discohesion. Results: The present case series describe two cases of malignant mela- noma with varying degrees of extensive melanocytic discohesion: the first shows acantholytic pattern mimicking pemphigus vulgaris, the second is a case of bullous melanoma. Discohesion between melano- cytes and between melanocyte and keratinocyte may reflect a more aggressive behaviour of melanoma with consumption being the epiphe- nomenon of progression of the melanoma itself, with loss of control of the keratinocyte-melanocyte relationship. The mechanisms leading to bullous, and acantholytic-like melanoma, are not known. Apart from melanocyte discohesiveness, local trauma may play a role. Discussion is still unclear whether undiscovered antigens contributed to this pat- tern of discohesion between melanocytes in similar cases. Conclusion: The histopathologist should be aware of this rare and peculiar presentation of a melanoma mostly for the implication in indi- cating the exact staging and prognostication of the patients. There are significant problems in estimating the Breslow index in cases such these and it is recommend subtracting the thickness of the blister to obtain a more accurate measurement. E-PS-05-019 Fumarate hydratase deficient pilar leiomyoma: a case report Z. Gramc*, V. Hosta, B. Hrvatin Stančič *Department of Dermatovenereology, University Medical Centre Lju- bljana, Slovenia Background & objectives: Pilar leiomyomas (PLs) are benign dermal smooth muscle tumours. Multiple PLs are commonly inherited and can be associated with hereditary leiomyomatsis and renal cell cancer syndrome (HLRCCS). HLRCCS is a result of heterozygous mutations in the fumarate hydratase (FH) gene. Methods: 39-year old male presented with multiple firm pink papules distributed in zosteriform pattern which he had for about two years, with new lesions appearing over time. He was otherwise healthy with no reported history of significant or hereditary diseases in the family. Clinical impression was keloid formation after herpes zoster infection. A punch biopsy was performed. Results: Histopathological examination showed dermal tumour com- posed of intersecting bundles of spindle cells with eosinophilic cyto- plasm and blunt-ended, elongated nuclei with perinuclear halos. Focal nuclear hyperchromasia, cytological atypia and rare mitoses were observed. Immunohistochemical studies revealed diffuse and strong immunoreactivity for smooth muscle actin, caldesmon and desmin, besides loss of FH was demonstrated. Diagnosis of FH deficient pilar leiomyoma was made. Patient was advised to undergo genetic testing. DNA mutation analysis of the FH gene was performed which detected heterozygous germline mutations in the FH gene. To our patient yearly genetic counselling and magnet resonance of abdomen were advised as well as genetic analysis for his children and siblings. Conclusion: PLs are difficult to diagnose by clinical evaluation, but can be easily recognized and confirmed with histological examination. Recognition of FH deficient PLs can lead to diagnosis of HLRCCS, a rare genetic disorder associated with benign cutaneous and uterine leiomyomas and aggressive renal cell carcinoma. Early identification, comprehensive clinical assessments and surveillance influences patient management and can provide positive outcomes to affected individuals and their families. E-PS-05-020 Primary cutaneous apocrine carcinoma on congenital nevus seba- ceus: a case report G. Güngör Sahin*, Y. Ozluk, M. Gulluoglu, S. Yucel, D. Yasar Aksoyler, S. Ozturk Sari *Istanbul University, Istanbul School of Medicine, Department of Pathology, Turkey Background & objectives: Apocrine carcinoma is rare cutaneous adnexal neoplasm with unclear histogenesis. Although commonly seen in the axilla, it may also occur on scalp. This case report outlines clin- icopathological characteristics and diagnostic challenges of primary apocrine carcinoma arising in nevus sebaseus background. Methods: A 62-year-old male patient presented with a congenital right parietotemporal mass, which had been progressively enlarging over the past decade and had developed ulceration within the most recent year. Excision was performed with a prediagnosis of squamous cell carcinoma. Results: Gross examination revealed an irregularly circumscribed, polypoid mass with a central ulcer. Microscopically, dermal tumoral infiltration with tubular structures of varying sizes were observed. Some tubular structures showed central necrosis. Eosinophilic cyto- plasmic protrusions and a decapitation sign were present in some cells. Immunohistochemistry was negative for ER, PR and D2-40, positive for AR and GATA3, focally positive for GCDFP15. p63 antibody highlighted the myoepithelial cells in the in situ component. Nevus sebaceus was observed surrounding the tumour. Conclusion: Apocrine carcinomas have been reported to arise from benign lesions such as spiradenoma, apocrine mixed tumour, and nevus sebaceus. Metastatic breast cancer should be considered in the differen- tial diagnosis, particularly for axillary lesions. The presence of nevus sebaceus background and in situ components facilitated the diagnosis of a primary apocrine carcinoma in our case. Meticilous microscopic and gross examination should be performed when necessary to identify the background lesion and demonstrate the in situ component. E-PS-05-021 CRTC1::TRIMM11 cutaneous tumour: a new entity G. Güngör Sahin*, I. Yılmaz, D. Yavuz Zor, S. Ozturk Sari *Istanbul University, Istanbul School of Medicine, Department of Pathology, Turkey