Hyperkeratosis refers to an abnormal thickening of the stratum corneum, a pathological change in which the epithelial cells on the surface of the skin or mucous membranes become hyperkeratotic and the stratum corneum becomes inflamed and thickened. It is often caused by exposure to or ingestion of certain chemicals, and can also be caused by viruses. Dermatoscopy and confocal microscopy (skin CT) are emerging non-invasive dermatological examinations that are of great utility in the diagnosis and differential diagnosis of dermatological diseases and can be a useful complement to histopathology. Dermoscopy can be used to exclude other dermatological conditions with similar clinical manifestations. Confocal microscopy shows microscopic details closely related to histological features: polygonal structureless areas reflect hyperkeratosis and hyperkeratosis, and in the epidermis, large round bright cells may correspond to round bodies.