Clinical Features of Verruca Plana and Verruca Plana-Like Seborrheic Keratosis

Background: Differentiating between verruca plana (VP) and VP-like seborrheic keratosis (SK) is difficult and little research has been performed on the topic. Objective: The aim of this study was to elucidate clinical differences between these two diseases. Methods: We conducted a retrospective review of cases of VP and VP-like SK identified by biopsy. Demographics (age and gender) and clinical information (location, color, distribution, and shape) were collected. Results: A total of 224 cases were identified. Thirty-nine cases were finally diagnosed with VP (17.4%) and 159 cases with VP-like SK (71.0%). The rest of the diagnoses accounted for 26 cases. On multivariate analysis, extremities (odds ratio [OR] 7.91, confidence interval [CI] 2.61~23.93), flesh color (OR 3.69, CI 1.43~9.49), erythematous color (OR 36.83, CI 7.50~ 180.84), and clustered distribution (OR 4.73, CI 1.66~ 13.46) were significantly associated with VP. Shape is not predictive in VP occurence. Conclusion: We provide clinical information regarding the differentiation of VP and VP-like SK, which should prove useful in clinical dermatological practice.