A dermatologist is trained to diagnose and treat pediatric and adult patients with benign and malignant disorders of the skin, mouth, external genitalia, hair and nails, as well as a number of sexually transmitted diseases. The dermatologist has had additional training and experience in the diagnosis and treatment of skin cancers, melanomas, moles, and other tumors of the skin, the management of contact dermatitis, and other allergic and nonallergic skin disorders, and in the recognition of the skin manifestations of systemic (including internal malignancy) and infectious diseases. Dermatologists have special training in dermatopathology--the diagnosis of skin diseases including infectious, immunologic, degenerative, and neoplastic--and in the surgical techniques used in dermatology. The care of the dermatology patient may entail both topical and systemic medical therapeutics and a variety of surgical and cosmetic procedures, including excisions, sclerotherapy, laser surgery, liposuction, hair transplants and tissue augmentation therapies, anti-aging treatments, injectable and implantable soft tissue fillers, correction of acne scarring, chemical peeling, vein therapy, skin cancer treatment, and reconstructive flaps and grafts. In addition, dermatologists have a role in the care of normal skin, skin cancer prevention, and sun protection.