ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 not highlight Merkel cells in these areas. The diagnosis mainly depends on morphology. Around 30 trichogerminomas were reported and are included in the spectrum of trichoblastomas. However, their presence within BCCs has not been well described or studied. These cases are not associated with Brook-Spiegler syndrome or any poor prognosis. Grainyhead-like transcription factor (GRHL1/2/3) gene rearrange- ments including FOXK1:GRHL1/2 fusion transcripts which are recently reported by Kervarrec et al in trichogerminomas have not been yet studied in this BCC subtype. Conclusion: We report a series of three cases of BCC with trich- ogerminoma-like areas, which is underreported and rare BCC subtype. The diagnosis is based mainly on tumour morphology expressing epithelioid cell balls. They also express a distinct immunohisto- chemical profile. Pure trichogerminomas have GRHL gene rearrangements but this is yet to be studied in cases associated with BBC. Complete excision of the tumour with adequate margins is the treatment of choice. There is no association with poor prognosis or Brook-Spiegler syndrome. PS-12-004 The value of peritumoral lymphocyte infiltration in progres- sion free survival in BRAF and NRAS mutant stage I and II melanoma: a retrospective cohort study T. Zablocka*, V. Kregere, S. Savcenko, L. Sulca, M. Kreismane, D. Pjanova, S. Isajevs *Faculty of Medicine, University of Latvia; Riga East University Hospital; Pauls Stradins Clinical University Hospital; Hospital of Traumatology and Orthopaedics, Latvia Background & objectives: The presence of tumour infiltrating lym- phocytes is a favourable prognostic factor in cutaneous melanoma. The current study’s objective have been to compare the NRAS and BRAF mutation status with peritumoral lymphocytic infiltration and progres- sion free survival in melanoma. Methods: Altogether, 85 patients underwent melanoma surgical treatment at the Riga East University Hospital, were retrospectively enrolled in the study. The histopathological characteristics were assessed. The melanoma BRAF and NRAS mutations status were assessed by PCR (ddPCR). Progression-free survival (PFS) was esti- mated with the Kaplan-Meier method with the log-rank test. Multivar- iate regression was analysed using Cox proportional hazards model. Results: There were 56 cases of nodular melanoma and 29 cases with superficial spreading melanoma. The BRAF mutation was observed in 52 patients (61.2%). The BRAF mutation in mela- noma correlated with Clark invasion level (p=0.045), patient age (p=0.02) and peritumoral lymphocytes (p=0.04). NRAS mutation was observed in 9 patients (10.6%). NRAS mutation correlated with Breslow thickness (p<0.0001), disease stage (p=0.002) and lymphovascular invasion (p=0.03). Our study showed that mela- noma patients with BRAF mutation had significantly better pro- gression-free survival (PFS) than patients with NRAS mutation (HR=4.2, 95% CI=2.8-10.4, p<0.0001). However, in patients with concomitant BRAF and NRAS mutation the PFS was significantly worse compared to patients with only BRAF or NRAS mutation. Conclusion: To conclude, the strength of our study was the dem- onstration of significant role of TIL and BRAF, NRAS mutational status in patients with stage I-II melanoma. Patients with NRAS mutation had significantly worse prognosis compared to patients with BRAF mutation. However, the increased TIL infiltration char- acterized by better prognosis. Funding: The study was supported by project “Strengthening of the capacity of doctoral studies at the University of Latvia within the framework of the new doctoral model” identification No. 8.2.2.0/20/I/006. PS-12-005 Clinicopathologic characteristics of BRAF V600K mutant malignant melanoma in comparison with V600E mutant cases: a preliminary study G. Bülbül*, A.A. Ağalar, E. Yumuk, S. Cagaptay, H. Ellidokuz, B. Lebe *Dokuz Eylül University Hospital, Turkey Background & objectives: BRAF V600K mutation, the second most common mutation in malignant melanoma with a rate of 10-30%, is related to worse response to treatment and adverse prognosis. However, data for comparing V600K/V600E groups for the histopathologic and prognostic features are limited. Methods: A total of 23 malignant melanoma cases with BRAF V600E or BRAF V600K mutations detected by pyrosequencing in our department were retrospectively analysed. The associations between the type of BRAF mutations and histopathologic, clinical and prognostic characteristics were statistically investigated. Results: Of the 23 cases, 7 (30.4%) had V600K and 16 (69.6%) had V600E mutation. Although there was no statistical significance between two groups, most of the cases with V600K mutation were male (85.7%). In BRAF V600K mutant cases, histologic type was mostly superficial spreading melanoma (85.7%), tumour localiza- tion was mostly head and neck (57.1%); ulceration and regression were slightly higher. In BRAF V600E mutant group, the number of mitosis (>10/HPF) was higher (81.3%). V600E mutant group was generally more advanced (pT4) at the time of diagnosis (75%). In survival analysis, the estimated survival time was shorter in patients with V600K mutation than those with V600E mutation (17.9 vs 33.2 months). Conclusion: Although it’s a preliminary study and no statistical significance was detected due to the low number of cases, our results emphasize that overall survival time is almost half as short in V600K mutant cases than those with V600E mutation. Considering the prognostic differences, since the double nucleotide change seen in the V600K mutation(GTG to AAG) includes the single nucleotide change seen in the V600E mutation(GTG to GAG), it’s important to be careful in the evaluation to distinguish these two mutations. PS-12-006 The clinicopathologic features of dysplastic nevus with severe cytologic atypia: single centre experience Y. Cakir*, B. Lebe *Dokuz Eylül University Institute of Health Sciences, Department of Molecular Pathology, Turkey Background & objectives: Dysplastic nevus with severe cytologic atypia are accepted as a significant intermediate lesion in malign mela- noma progression. We aimed to summarize the clinicopathological findings of cases as diagnosed dysplastic nevus showing severe cyto- logic atypia at a single institution. Methods: We reviewed the pathology reports of excisional skin biopsies of 644 cases and 1226 lesions as diagnosed dysplastic nevus between 2010 and 2021, retrospectively. The cases having severe cytologic atypia and their clinicopathologic features were noted. S130