<p>Seborrheic keratosis (SK) is a benign epidermal keratinocytic tumor that is extremely common, particularly in individuals over the age of 50. Most individuals with SK will have more than one lesion and the presence of over 10 lesions in the same person is not uncommon. Although the clinical morphology of most SK with their stuck-on, symmetric, keratotic, and waxy appearance makes them easy to identify, many manifest a morphology resembling melanoma or squamous cell carcinoma. One can argue that such cases will ultimately not prove to be problematic since a simple biopsy will easily reveal their benign nature and eliminate any concerns. However, the cost and morbidity associated with the biopsy of benign lesions should not be underestimated. Methods to improve our in vivo ability to correctly identify SK will prove beneficial not only to the health care system in general but to the individual patient specifically. The issue of greater concern resides with skin cancers that mimic SK or when skin cancers arise in association with SK. Needless to say, in vivo methods to help identify malignancy and differentiate them from benign lesions would be welcomed by all. Fortunately, we do now have in vivo imaging methods such as dermoscopy that can improve the clinician's diagnostic accuracy. In this article, we summarize the current knowledge regarding the clinical and dermoscopic features of SK, and provide clues to aid in their diagnosis.</p> <p><em>J Drugs Dermatol. 2017;16(9):835-842.</em></p>.