Dermoscopy can be used to examine seborrheic dermatitis, sebaceous gland hyperplasia, sweat duct tumors, rosacea and many other skin diseases. 1. Seborrheic dermatitis: Clinical manifestations include increased oiliness of the skin, which may be accompanied by uncomfortable symptoms such as macular rash, scaling and itching. Dermoscopic manifestations include fine yellow scales on a red or yellowish-red background, yellowish-red oil droplet halos around hair follicles, and focally distributed punctate, atypical, or linear branching vasodilatation. 2. Sebaceous gland hyperplasia: Clinical manifestations are skin-colored or slightly yellowish papules, often depressed in the center. Dermoscopic features are clearly defined creamy or yellowish-white cloud-like structures (cumulus sign). 3. Sweat duct tumor: Clinical manifestations of multiple scattered distribution of skin color flat papules, more corn size. Dermoscopy shows multiple round, yellowish-white structures surrounded by a thin, light brown pigmented network, or hypopigmented areas. 4. Rosacea: Clinical manifestations include redness of the face aggravated by heat or tension, accompanied by capillary dilatation, or small pustules on the nose. Dermoscopy shows a network of polygonal blood vessels on a dark red background. Other features include rose petal sign, follicular pustules and dilated follicular orifices. It should be noted that dermoscopy is highly specialized, and it is recommended that the patient go to a regular hospital and have a doctor perform this operation.