ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 for a 2.5 cm indurated and painful violaceous nodule in the plan- tar region (head of the 5th metatarsal, left foot) of 6 months of evolution. Ultrasound findings were suspicious for mesenchymal neoplasia and a biopsy of the lesion was performed. Results: Histological study showed abundant collagen bundles with spindle cells arranged in a storiform pattern around the blood vessels in the superficial and deep dermis. They were accompanied by mixed inflammatory infiltrate with lymphocytes and neutrophils as well as isolated images of leukocytoclastic vasculitis. The fol- lowing immunohistochemical (IHC) techniques were performed: EMA, Desmin, AML, claudin, CD34 and s100 were negative. The ki-67 proliferation index was less than 10%. The clinicopathologic and IHC findings together with the presence of leukocytoclastic vasculitis helped in the diagnosis of EED. Conclusion: The histopathologic features of EED vary according to the age of the lesions, with development of variable fibrosis and fasciculated spindle cell proliferation in late stages. The differential diagnosis is made with an inflammatory pseudotumour, dermatofibrosarcoma protuberans, sclerotic neurofibroma, sclerosing perineuroma, tendon sheath fibroma, and hyalinized leiomyoma. The aetiology of EED is unknown; it has been proposed to be an immunocomplex-mediated disease, with viral or bacterial antigens being involved, which would explain the association between EED and CD. E-PS-05-034 The clinical and pathological features of nevus associated melanomas B.R. Nataras*, A. Plopeanu, V. Popa, A. Dema *Department of Microscopic Morphology-Pathology, ANAPAT- MOL Research Center, ’’Victor Babes’’ University of Medicine and Pharmacy of Timisoara, Romania Background & objectives: The purpose of this study was to identify the cases of nevus associated melanomas (NAMs), evaluating the clini- cal and pathological features. Methods: From the database of our pathology department, we selected the cases diagnosed as primary cutaneous melanomas between 2016 and 2021, extracting the nevus associated melanoma cases. Results: We identified 213 cases of cutaneous melanomas, the NAMs representing 10% (21 cases) - 66.6% females, 33.3% males. The median age at diagnosis was 50 years (females) and 56 years (males). The majority of the NAMs presented a dysplastic nevus (52%). Superficial spreading melanomas, with a vertical growth phase predominated (57%), followed by melanoma in situ (14%). In the invasive melanoma group (18 cases), we noticed more often a Breslow index ≤ 1mm (45%), a II&III Clark level (50%), a pT1 stage (50%), a mitotic rate of 1 mitosis/mm² (55%) and brisk inflammatory infiltrate (50%). Conclusion: The median age of the females diagnosed with NAMs was lower compared with the median age of the males. The majority of the NAMs were represented by superficial spreading melanomas with a vertical growth phase, in the presence of a dysplastic nevus. In these cases predominated a low Clark level and Breslow index, a decreased pathological stage and mitotic rate, being associated more often with a brisk inflammatory infiltrate. E-PS-05-035 Metastatic male breast carcinoma in the skin. Report of a rare case M. Mnikhovich*, A. Romanov, T. Bezuglova, D. Pastukhova *Central Pathology Laboratory, Research Institute of Human Mor- phology, Russia Background & objectives: Breast cancer is one of the rarest malignancy in men. These tumours have a high tendency to hematogenous metastasis, often affecting the bones, lungs and liver. Although in some cases, lesions of atypical organs, such as skin, are also possible. Methods: We present a case of metastatic invasive ductal breast carcinoma to the skin in a young male. In 2015 he underwent complex treatment invasive ductal carcinoma of the left breast. In 2021, he was again admitted with a painless mass of the skin of the scalp measuring 2x2.5x2 cm. A biopsy was performed followed by a histological and IHC study. Results: Histological examination revealed the tumour composed of cells with eosinophilic cytoplasm and oval pleomorphic nuclei, with indistinct cell and nuclei boundaries. Tumour cells form cord- like, glandular and cribriform structures that infiltrate the dermis and subcutaneous fatty tissue. The tumour wasn’t associated with the epidermis. The IHC study showed that tumour cells expressed CK7, GCDFP15, GATA3, ER, PR, and HER-2. Also was the lack of expression CK20 and all melanocytic markers in the tumour. The immunophenotype of the tumour corresponds to a previous carcinoma of the breast. The diagnosis of metastatic invasive breast carcinoma NST type was made. Conclusion: In this article we have presented a rare case of meta- static male invasive breast carcinoma of NST type in the skin of the scalp. This case expands our understanding of the nature of metastatic skin cancers and once again proves that when you see stripes, it can still be tigers. E-PS-05-036 A case of acantholytic squamous cell carcinoma of the skin Z. Lajmi*, A. Bdioui, M. Krifa, S. Mestiri, O. Belkacem, S. Hmissa *Department of Pathology, Farhat Hached University Hospital, Tunisia Background & objectives: Acantholytic squamous cell carcinoma (ASCC) is an uncommon high-risk histopathologic variant of cutane- ous squamous cell carcinoma (SCC). It is generally more aggressive and have a worse prognosis than the other SCC subtypes. The exact diagnosis is challenging. Methods: A 63-year-old man, with no history, presented with an erythematous nodule in the temporal region since 4-months. On examination, a non-inflamed slightly pruritic hyperkeratotic papule was located in the temporal region. Clinically, prurigo nodularis, seborrheic keratosis, and SCC were suspected. A biopsy was per- formed for making the diagnosis. Results: On microscopic examination, the tumour was composed of epidermal-derived cystic proliferation extending into the super- ficial dermis with acantholysis foci in tumour nests, creating the appearance of glandular differentiation. This aspect is due to the loss of intercellular cohesion between malignant squamous cells. The pseudolumina contained acantholytic and atypical dyskeratotic cells, and cellular debris. There was no evidence of true glandu- lar differentiation or mucin production. The overlying epidermis showed hyperkeratosis and parakeratosis. On the immunohisto- chemical studies, the acantholytic tumour cells were positive for CK with a cytoplasmic staining pattern and for p40 supporting a squamous epithelial origin. Final diagnosis of ASCC was retained. Conclusion: ASCC is characterised histologically by a combination of typical SCC and pseudoglandular structures, S215