the four-year training period, the doctor becomes an accredited dermatologist and is able to apply for a consultant hospital post as a consultant dermatologist. Fields Cosmetic dermatology Dermatologists have been leaders in the field of cosmetic surgery. Some dermatologists complete fellowships in surgical dermatology. Many are trained in their residency on the use of botulinum toxin, fillers, and laser surgery. Some dermatologists perform cosmetic procedures including liposuction, blepharoplasty, and face lifts. Most dermatologists limit their cosmetic practice to minimally invasive procedures. Despite an absence of formal guidelines from the American Board of Dermatology, many cosmetic fellowships are offered in both surgery and laser medicine. Dermatopathology A dermatopathologist is a pathologist or dermatologist who specializes in the pathology of the skin. This field is shared by dermatologists and pathologists. Usually, a dermatologist or pathologist completes one year of dermatopathology fellowship. This usually includes six months of general pathology and six months of dermatopathology. Alumni of both specialties can qualify as dermatopathologists. At the completion of a standard residency in dermatology, many dermatologists are also competent at dermatopathology. Some dermatopathologists qualify to sit for their examinations by completing a residency in dermatology and one in pathology. Trichology Trichology specializes in diseases, which manifest with hair loss, hair abnormalities, hypertrichosis and scalp changes. Trichoscopy is a medical diagnostic method that is used by dermatologists with a special interest in trichology. Immunodermatology This field specializes in the treatment of immune-mediated skin diseases such as lupus, bullous pemphigoid, pemphigus vulgaris, and other immune-mediated skin disorders. Specialists in this field often run their own immunopathology labs. Immunodermatology testing is essential for the correct diagnosis and treatment of many diseases affecting epithelial organs including skin, mucous membranes, gastrointestinal and respiratory tracts. The various diseases often overlap in clinical and histological presentation and, although the diseases themselves are not common, may present with features of common skin disorders such as urticaria, eczema and chronic itch. Therefore, the diagnosis of an immunodermatological disease is often delayed. Tests are performed on blood and tissues that are sent to various laboratories from medical facilities and referring physicians across the United States. Mohs surgery The dermatologic subspecialty called Mohs surgery focuses on the excision of skin cancers using a technique that allows intraoperative assessment of most of the peripheral and deep tumor margins. Developed in the 1930s by Dr. Frederic E. Mohs, the procedure is defined as a type of CCPDMA processing.