Role of dermoscopy in diagnosing and differentiating seborrheic keratoses: a case study of 100 patients

Background Seborrheic keratosis is one of the most common benign epidermal tumors seen in elderly individuals. It has slow growth and presents with a varied degree of pigmentation in skin color closely resembling many other pigmented dermatoses. Dermoscopy, a noninvasive technique, could increase the accuracy of diagnosis and can differentiate it from various closest mimickers and malignancies. Aim This study aims to describe the various dermoscopic features of seborrheic keratosis in a series of cases. Patients and methods A hospital-based, descriptive study was conducted over 12 months from January 2018 to December 2018 in the Department of Dermatology, a tertiary-care center. A total of 100 patients were selected and evaluated in a prestructured proforma concerning age, sex, site of lesion, number and duration, and associated comorbidities. The lesion is observed on dermoscopy, and the dermoscopic patterns were then documented and analyzed. Result Among a total of 100 (32%) cases, the most common age group was between 41 and 50 years with females (52%) outnumbering males (48%). The most common site was the face (38%), and the common morphology was plaque (60%). Sign of Leser-Trélat was observed in five patients of which three were associated with malignancy that includes two lymphomas and one breast carcinoma. The color on dermoscopy was predominant dark brown (43%) and brownish-black (32%). The common element was clod (39%) and combined clod and dots (18%). More than three colors and more than two elements in a single lesion were observed in 15 and 11% of cases, respectively. The dermoscopic clues of seborrheic keratosis with highest to lowest prevalence were cerebriform pattern (76%), sharp demarcation (64%), comedone-like opening (56%), milia-like cyst (54%), mica-like scales (52%), moth-eaten border (46%), jelly sign (40%), fingerprint-like pattern (40%), fat fingers (36%), peripheral globules/network (34%), coral-like structure (26%), papillary structures (26%), irregular globules (12%), irregular opaque brown pigmentation (12%), and yellow-orange areas (3%). The flat seborrheic keratosis predominantly showed an irregular network-like structure, fat fingers, milia-like cyst, and accentuation of two adjacent perifollicular pigmentations forming a double ring-like structure (16%). The raised lesions predominantly showed fissures/ridges (cerebriform pattern), exophytic papillary structures, opaque pigmentation, and a mica-like pattern. Ten lesions were misinterpreted as seborrheic keratosis clinically and on dermoscopy were verruca vulgaris (2/10, 20%), melanocytic nevus (3/10, 30%), and basal cell carcinoma (5/10, 50%), which were confirmed on histopathology. Conclusion The study emphasizes the use of dermoscopy in seborrheic keratosis to improve the clinical accuracy of diagnosis and also to differentiate from its common mimickers.