ECP 2023 Abstracts

S181 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 was found between mean tissue lymphocyte and CRP (p=0.025). The high peripheral eosinophilia group had a more widespread disease (p=0.034), and cases with peripheral eosinophilia had a higher rate of complete remission (p=0.027). There were no significant differences between tissue eosinophil count and ESR, CRP, mucosal involvement, severity of lesions, and treatment response. Conclusion: Tissue eosinophil count and peripheral eosinophilia are closely related. Peripheral eosinophilia was associated with disease severity and treatment response, while tissue eosinophil count was not correlated with clinical features. While the presence of periph- eral eosinophilia was found to be inversely correlated with treatment response, the results also showed a negative correlation between tissue eosinophil count and mucosal involvement and treatment response. High comorbidity and advanced age in this patient group made disease control challenging, leading to potentially different study results. E-PS-05-007 CD4/CD8 double positive and CD4/CD8 double negative mycosis fungoides: a preliminary study E.K. Çagdas*, A. Okçu Heper, N. Özben, H. Şanli, B.A. Kirmizi, B.N. Akay *Ankara University School of Medicine, Department of Pathology, Turkey Background & objectives: In Mycosis fungoides (MF), the neoplastic lymphocytes expected to be CD4+ but they may be CD8+, double CD4-/CD8-, double CD4+/CD8+ with decreasing frequency. In this study, we aimed to analyse clinical and histopathological features of double CD4+/CD8+ and CD4-/CD8-cases. Methods: Among total 651 MF diagnosed cases since 2005, selected 6 CD4+/CD8+ and 14 CD4-/CD8- MF cases were reexamined histo- pathologically, grouped as “double-positive group(DPG)” or “double- negative group(DNG)” according to CD4 and/or CD8 staining. Addi- tional 41 CD4+ and 45 CD8+ cases were reexamined as a control group. The data evaluated with Chi-square, Kruskal-Wallis, Student’s T tests in SPSS22 program. Results: The severity of lymphocytic atypia in the double-positive group was significantly higher according to both the CD4+ (p=0.008) and CD8+ (p=0.002) groups. Loss of CD5 seen significantly less in the DPG according to both the CD4+ (p=0.000) and the CD8+ (p=0.000) groups. Both the DPG and DNGs affected significantly younger popu- lation comparing to the CD4+ group (p=0.002; p=0.000, respectively). Both in DPG and DNG either immunophenotypic conversion or similar immunophenotype was observed in consecutive biopsies. No statisti- cally significant relation between immunophenotypic conversion with the duration of the lesions or the treatment applied were detected. No significant prognostic difference was not observed between the all DPG, DNG, CD4+, CD8+ MF groups. Conclusion: Although epidermotropism of CD4+ atypical T lympho- cytes is accepted as one of defining feature of MF which is well-known mimicry of various dermatitis and cutaneous lymphomas, CD4/CD8 double-negative and double-positive cases may cause diagnostic prob- lems. Langerhans cells are considered as tricky component causing troubles defining immunophenotypical feature of intraepidermal cells. Besides the detected some histopathological distinct features like lym- phocytic atypia, the preliminary results of study showed no significant clinical difference is present comparing to CD4+ MF and CD8+ MF. E-PS-05-008 Palmoplantar psoriasis: a clinico-pathologic study on a series of 21 cases with emphasis on differential diagnosis R. Caltabiano*, M. Failla, A. Palicelli, M. Zanelli, F. Sorci, G. Broggi *Department of Medical and Surgical Sciences and Advanced Tech- nologies "G. F. Ingrassia", Anatomic Pathology, University of Catania, Italy Background & objectives: Palmoplantar psoriasis is a variant of pso- riasis, that shares clinical and histologic features with eczema, hand dermatitis and allergic contact dermatitis. The present study aims to characterize the histologic features of palmoplantar psoriasis on a series of 21 cases. Methods: The following morphological features and their distribu- tion were included: parakeratosis, dilated vessels in papillary dermis, psoriasiform acanthosis with elongation of rete ridges, perivascular lymphocytic infiltrate, decrease/loss of granular layer, Munro’s micro- abscesses, spongiform pustules of Kogoj, spongiosis and lymphocytic exocytosis. Results: A total of 21 adult patients with histopathologically proven palmoplantar psoriasis were included. In all cases, exhibited par- akeratosis and parakeratotic areas, that alternated both vertically and horizontally with orthokeratotic areas. The features we observed more frequently included: parakeratosis alternated with orthokeratotic areas, presence of congested, dilated, and tortuous vessels in the papillary dermis, and decrease/loss of the granular layer. These findings, includ- ing neutrophils in the stratum corneum, could be considered a diagnos- tic clue of palmoplantar psoriasis. Conclusion: The main diagnostic clues and histologic differential diag- noses are also presented. E-PS-05-009 Pinkus and the enigma of the skin basal cell carcinoma variants? A two-cases report I.G. Cocuz*, R. Niculescu, A.H. Sabau, M.C. Popelea, O.S. Cotoi *UMFST Targu Mures, Romania Background & objectives: The fibroepithelial basal cell carcinoma (Pinkus tumour) is a non-melanocytic skin cancer type, classified by the WHO Skin tumour classification 2018 as being a variant of basal cell carcinoma. The origin of this rare tumour is still disputed. Methods: We present two cases of Pinkus tumour from two female patients aged 53 and 68 years old who had a surgical excision of a small coloured nodule on the lumbar region. The tissue samples were sent to the Pathology Department for the histopathological diagnostic. H&E staining and immunohistochemistry (Bcl-2, CK AE1/AE3, Ki67) were performed. Results: Microscopically, a tumour cell proliferation was observed, composed of strands of tumour cells with a basaloid aspect which were arising from the epidermis. The tumour cells were of small dimensions, and presented cito-nuclear atypia, with reduced basophilic cytoplasm and enlarged hyperchromatic nuclei. In-between the tumoral cords, a fibrous stroma was observed. No basaloid tumour cells islands were present. Immunohistochemically, the tumoral cells were positive for Bcl-2 and CK AE1/AE3. The Ki67 proliferation index was about 5-10% in the tumoral cells. The tumour was completely removed in the surgi- cal safety limits. Conclusion: Even though the Pinkus tumour is rare, the histopatho- logical diagnostic should be based on the characteristic basaloid cells arranged in strands. Our two cases had a very similar aspect and based on the H&E and immunohistochemically profile, the diagnostic of Pinkus tumour was established. The origin of the tumour is still disputed between basal cell carcinoma and trichoblastoma, but in general, the complete excision of the tumour is the indicator for a good outcome of the patient. E-PS-05-010 Are nevus remnants associated with the incidence of LMM? E. Colon*, I. Drakensjö *UNILABS SWEDEN, Sweden Background & objectives: Previous studies have shown that LMM is less likely to have evidence of nevus remnants compared to other