ECP 2023 Abstracts

S192 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 profile without true rhabdomyoblastic differentiation; thus the diagno- sis is easily established. Rhabdomyoblastic differentiation in primary cutaneous melanomas has been acknowledged in less than 10 cases to date. These lesions may not express melanocytic markers such as HMB45 and Melan-A. Therefore, extensive immunohistochemical analysis should be performed. PRAME is particularly useful as SOX10 is also positive in malignant peripheral nerve sheet tumours with rhab- domyosarcomatous elements. E-PS-05-048 Verruca vulgaris overlying basal cell carcinoma: an association never described before H. Trihia*, E. Souka, G.M. Stanc, G. Sgouros *Pathology Department Metaxa Cancer Hospital, Greece Background & objectives: Multiple neoplasms at the same cutane- ous site, is known as multiple-skin-lesions at one site (MUSK IN A NEST). Basal cell carcinoma (BCC) presents as isolated tumour, or as collision tumours. The combination with common wart has not been described before. Methods: A 67-year old man presented to our Dermatology Clinic for evaluation of a lesion behind his ear. He was uncertain of its duration. He reported cauterization of a lesion in the same area at the age of 12 and traumatisation during wearing of his motorcycle helmet. Physical examination revealed a 3cm raised, smooth, circumscribed, hyperkera- totic papule with solid cut surface. Results: Histopathology confirmed three different lesions in associa- tion. An overlying common wart (CW) with hyperkeratosis, papillo- matosis, hypergranulosis and columns of parakeratosis over projecting dermal papillae, corresponding to a dome-shaped papule with a kera- totic and verrucous surface. There was intracorneal haemorrhage and inward bending of rete ridges at the borders of the lesion. A nearby, microscopic slightly elevated seborrheic keratosis and an underlying of the CW, 0,7cm BCC, was diagnosed. The BCC component was positive for Ker5/6, p63, p40 and BerEP4 and negative for EMA, CK20 and melanocytic markers. The final diagnosis was of a combined lesion, consisting predominantly of a verruca vulgaris, overlying a BCC, in association with the overlying epidermis. Conclusion: Verruca vulgaris is an-HPV-induced cutaneous lesion. The relationship between BCC and co-existing conditions may be coincidental or possibly related to the development of the BCC. BCC is likely to be secondary to a koebner isomorphic or a Wolf isotopic response in an immunocompromised skin. Malignant transformation of CW into SCC and BCC has been reported. Imiquimod has been used in large lesions of superficial and nodular BCC. Our case may add to the histogenesis. Skin lesions should be fully included. E-PS-05-049 A case series of post-herpetic Wolf’s isotopic response E.M. Vázquez Tarrio*, M. Veras, J.L. Rodríguez Peralto, M.C. Gar- rido Ruiz *Hospital 12 de Octubre, Spain Background & objectives: Wolf’s isotopic response is the appearance of a new skin disease at the site of an already healed, unrelated disease, often herpes zoster. Multiple entities have been described as secondary diseases. We aim to further characterize this phenomenon. Methods: We present a retrospective case series of patients with Wolf’s isotopic response diagnosed in Hospital 12 de Octubre in the last two years, and analysed the clinical and histopathological variables (age, sex, initial and secondary lesions). A literature review was also conducted. Results: Three cases of Wolf’s isotopic response were reviewed. Two of the patients were men, with an average age of 65 years (range: 31-86 years). All the cases presented with herpes zoster as the initial dis- ease and a non-tumoral disease as the second; Erythema multiforme in one of the cases, Lichen planus in another one and Darier disease in the third one. The diagnosis of herpes zoster was clinical, and a histologic study was performed in the second dermatosis in all cases. Time between the debut of the first and the second dermatosis was not available because there was no histological confirmation of the lesion throughout its clinical evolution. Conclusion: Wolf’s isotopic response is a rare phenomenon, and its mechanism is not clear, though it has been suggested that it may be an alteration of local skin immunity. It is important to be aware of this phenomenon, to distinguish the suspected lesions from common relapses of herpes-zoster infection and primary inflammatory derma- titis and prevent a diagnostic delay of a second and potentially aggres- sive disease. E-PS-05-050 A case of Langerhans cell histiocytosis with cutaneous involvement and review of literature M. Veras*, E.M. Vázquez Tarrio, J.L. Rodríguez Peralto, M.C. Gar- rido Ruiz *Pathology Department, Hospital Universitario 12 de Octubre. Madrid, Spain Background & objectives: Langerhans cell histiocytosis (LCH) is the most common type of histiocytosis and shows clonal proliferation of activated Langerhans cells (LC) with systemic involvement. We aim to further characterize the clinicopathological features of this entity. Methods: We report a case of LCH with cutaneous involvement and summarize the epidemiological, clinical and histopathological features of this entity based on a review of previous literature. Results: A 23 month-old male patient that started at the age of 3 months, with bone multifocal affection. A biopsy of the mandibular branch diagnosed a Langerhans cell histiocytosis (LCH). The patient received treatment with progression of bone lesions for the next 2 years. Then, started with systemic symptoms such as insipid diabetes, anaemia, and desquamative lesions in skin that started in the scalp and progressed. Skin and bone marrow biopsies were performed and showed infiltration of LCH. The cutaneous lesion stained for S100 and CD1a. After treatment with ARA-C, corticoids and Cladribina the patient stabilized and has maintained a non active systemic disease. Conclusion: LCH shows a broad range of clinical manifestations and the diagnosis is based on clinical, radiological and histopathological findings. It is an uncommon condition that is more frequent in paedi- atric age (less than 10 years) and the suspicion would lead to an early diagnosis and treatment leads to a favourable prognosis for the patient. E-PS-06 | E-Posters Digestive Diseases Pathology - GI E-PS-06-001 The prognostic Impact of PD-L1, CD73, A2ar and CTLA-4 immu- nohistochemical expression in colorectal cancer L. Aboelnasr*, A.G. Abdou *Pathology Department, Menoufia University, Egypt Background & objectives: The interactions in the tumour microenvi- ronment are complex and dynamic, playing key roles in modulating the immune response, which impact cancer progression. This study aimed to evaluate the immunohistochemical expression of PD-L1, CD73, A2ar and CTLA-4 in colorectal cancer (CRC). Methods: This retrospective study included 103 surgically resected human CRC tissues, 22 adenoma cases and 21 non-neoplastic speci- mens. Using immunostaining technique, the immunohistochemical expression levels of PD-L1, CD73, A2ar and CTLA-4 were assessed and reported as scores considering both intensity and percentage of positivity. We evaluated the intercorrelations between the 4 biomarkers,