Background/Objectives: Non-melanoma skin cancers (NMSC) are the most frequent cutaneous tumors globally. Basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) represent the most frequently encountered representatives of this group and may represent a diagnosis challenge in some circumstances of hard to differentiate tumors. The aim of this study was to determine the factors that influence the diagnosis of NMSC and their impact. Methods: A single center, descriptive, retrospective study was performed, with a total of 866 cases from 678 patients from 2016-2022. Cases were then analyzed based on their histological diagnosis and characteristics and the available clinical data. Results: From the 866 cases, 709 were histologically diagnosed as BCC and 157 as SCC. The clinical accuracy for BCCs was 95% whereas for SCCs was 62% with both having large variations among attending dermatologists. Clinical factors that were found to influence the diagnosis were: advanced age (p<0.001), a biopsy beforehand (p=0.009), and multiple diagnosis or uncertainty (p=0.005) were predictive for a final diagnosis of SCC. Factors predicting BCCs were: the presence of multiple lesions (p=0.032), presence of ulcerations (p<0.001), age under 50 (p=0.002). BCCs were more likely to be correctly diagnosed than SCC (p<0.001). Cases with multiple BCCs were thinner compared to single-lesion excisions (p<0.001). A tumor reduction was observed after the 2020 the SARS-CoV-2 (p=0.023). Conclusions: Differentiating NMSC can be challenging, but several trends have been observed which may aide in further improving the diagnosis rates especially for SCCs.

Introduction & Objectives: Seborrheic keratoses (SK) are common benign skin tumors that are typically easy to diagnose. However, some SKs can be challenging and may be confused with malignant tumors. Our objective was to identify clinical factors in the diagnosis and management of SK Materials & Methods: A single-center, retrospective, descriptive study was performed based on data between 2016 and 2022. A total of 365 cases with a conclusive histopathological diagnosis of SK and complete clinical data were selected. Results: In total, 146/365 (40%) were correctly diagnosed as SK. The remaining 219/365 (60%) were mostly diagnosed as nevi, basal cell carcinoma, squamous cell carcinoma and melanoma. The diagnostic accuracy among physicians varied from 22% to 46%. For one physician, age influenced the clinical diagnosis (p=0.039). In the non-SK group, elderly patients had a tendency to have multiple excised lesions (p=0.045). The COVID-19 pandemic did not significantly affect the assessment criteria evaluated, except for the prioritization of larger SKs in 2020 than those excised in 2019 (p=0.049). Head lesions were more likely to have positive margins: 10/16 in the SK group vs 1/15 in the non-SK group (p=0.0052). The most common histological variant was the hyperkeratotic SK observed in 28.5% of cases. No histological variant had influence on the clinical diagnosis. Conclusion: Although SK are benign, they can present a clinical challenge in specific cases. Age, dimensions, experience and the number of lesions should be carefully considered when excising a lesion. Exposed areas are at risk of incomplete excisions.