Study of seborrheic keratosis by dermoscopy using polarized and nonpolarized modes

Background: Seborrheic keratosis (SK) is the most common benign skin tumor. Dermatoscope is a simple noninvasive diagnostic tool. Although SK has been well recognized clinically, dermoscopically, and histopathologically, data regarding dermoscopic differentiation of different types of SK using the polarized (P) and nonpolarized (NP) modes of dermoscopy are inadequate. Objectives: The objective was to study the dermoscopic pattern of different types of SK under P and NP dermoscopic modes. Methodology: A descriptive study of 102 patients was carried out after ethical approval. All patients attending the dermatology outpatient department with lesions who were willing to participate in the study were included in the study after taking written informed consent. After a detailed history and examination, clinical and dermoscopic photographs were taken under the P and NP modes of a dermoscope attached with a smartphone camera. Biopsy of the same lesions was sent for a histopathology examination. Results: A total of 102 patients were studied. Females (58) outnumbered males (44). The most common clinical variant was common SK. The most common histopathological type of SK was hyperkeratotic followed by acanthotic type. Sharp demarcated border (75%) was the most common finding on dermoscopy in our study followed by fissure and ridges (63%), scales (54%), comedo-like opening (34%), cobblestone-like pattern (33%), moth-eaten border (17.7%), and cerebriform pattern (13.7%). Conclusion: NP mode helps in better visualization as well as depth perception, whereas P mode shows better color perception and sharpness of superficial as well as deep dermoscopic structures.