Dermatology (from Greek d??µa, derma, "skin"; and -????a, -logia) is a branch of medicine dealing with the skin and its appendages (hair, sweat glands, etc).
Subspecialties
The skin is the largest organ of the body and is the most visible. Although many skin diseases are isolated, some are manifestations of internal disease. Hence, a dermatologist is schooled in aspects of surgery, rheumatology (many rheumatic diseases can feature skin symptoms and signs), immunology, neurology (the "neurocuteaneous syndromes", such as neurofibromatosis and tuberous sclerosis), infectious diseases and endocrinology. The study of genetics is also becoming increasingly important.
Venereology and phlebology
Venereology, the subspecialty that diagnoses and treats sexually transmitted diseases, and phlebology, the specialty that deals with problems of the superficial venous system, are in some countries part of a dermatologist's expertise.
Cosmetic dermatology
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Dermatologic surgery
Dermatologic surgery (dermasurgery) is performed by all dermatologists. Surgery is an integral part of dermatology residency training; thus all dermatologists are well trained in cutaneous surgery. In North America specialized training through a 1 year dermatologic surgery fellowship is available upon completion of the dermatology residency, and usually focuses on training in Mohs' micrographic surgery. Most dermatologic surgeons who have a special interest in this field apply for fellowship status with the American College of Mohs Surgery[1]; or the American Society for Dermatologic Surgery.
Techniques available to a dermatologic surgeon include lasers, traditional scalpel surgery, electrosurgery, cryosurgery, photodynamic therapy, liposuction, blepharoplasty (cosmetic eyelid surgery), minimally-invasive facelift surgery (e.g., the S-lift), and a variety of topical and injectable agents such as dermal fillers including fat transfer and hyaluronic acid. Some specially trained dermatologic surgeons perform Mohs surgery, which can be an effective method for the treatment of recurrent, indistinct, or difficult skin cancers.
Diagnosis
Any mole that is irregular in color or shape should be examined by a dermatologist to determine if it is a malignant melanoma, the most serious and life-threatening form of skin cancer. Following a visual examination and a dermatoscopic exam (an invaluable new instrument that illuminates a mole without reflected light), a dermatologist may biopsy a suspicious mole. If it is malignant, it will be excised in the dermatologist's office.
Medical history
The first step of any contact with a physician is the medical history. In order to classify a cutaneous eruption, the dermatologist will ask detailed questions on the duration and temporal pattern of skin problems, itching or pain, relation to food intake, sunlight, over-the-counter creams and clothing. When an underlying disease is suspected, an additional detailed history of related symptoms will be elicited (such as arthritis in a suspected case of lupus erythematosus).
Physical examination
Dermatology has the obvious benefit of having easy access to tissue for diagnosis. Physical examination is generally done under bright light and preferably involves the whole body. At this stage, the doctor may apply Wood's light, which may aid in diagnosing types of mycosis or demonstrate the extent of pigmented lesions, or use a dermatoscope which enlarges a suspected lesion and visualizes it without reflected light. The dermatoscope is helpful in differentiating a benign naevus from melanoma or a seborrheic keratosis from a mole. A morphological classification of dermatological lesions is important in the diagnosis of dermatological disorders. Dermatologic diagnosis is often dependent upon pattern recognition of lesions and symptoms.
Microbiology
Culture or Gram staining of suspected infectious lesions may identify a pathogen and help direct therapy.
Biopsy
If the diagnosis is uncertain or a cutaneous malignancy is suspected, the dermatologic surgeon may perform a small punch biopsy (using a local anesthetic) for examination under the microscope by the dermatologist who is a trained dermatopathologist.
Therapy
The skin is obviously accessible to topical local therapy. Antibiotic creams can help eliminate infections, while inflammatory skin diseases (such as eczema and psoriasis) often respond to steroid creams or topical anthralin. Dermatologists are innovators of new immune enhancing treatments, like topical imiquimod for superficial cancers and injection immunotherapy for warts as discussed below.
Topical medications
Topical medications treat many dermatological diseases, but dermatologists also use oral medications. Antibiotics and immune suppressants or immune enhancing agents (injection immunotherapy or topical imiquimod) for dermatological diseases or tumors. Isotretinoin ("Accutane") is used for severe cystic acne vulgaris and often produces a lifetime remission of this disfiguring disease. Isotretinoin prescribing in the U.S. is now controlled by a cumbersome FDA governmental website called iPLEDGE. Various new modalities of treatment are in the foray; with the advent of laser technology things are quite promising.
Photomedicine
Photomedicine involves the use of ultraviolet light, often in combination with oral or topical agents, to treat skin disease (e.g., psoriasis or mycosis fungoides).
Surgical therapies
Surgical intervention by a dermatologic surgeon may be necessary, for example, to treat varicose veins or skin cancer. Varicose veins can be treated with sclerotherapy (injecting an agent that obliterates the vein) or the long-pulsed Nd:YAG laser. Skin cancers can be managed with excision (including Mohs cancer surgery), cryosurgery, x-ray, or with the recent topical immune enhancing agent imiquimod. (See above section on "Dermatologic Surgery" for more details.)
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