History and physical examination are adequate for diagnosing many skin lesions. Some require biopsy or other testing.
Dermatologic History
Important information to obtain from history includes
Personal or family history of atopy (suggesting atopic dermatitis)
Occupational exposures (contact dermatitis)
Long-term exposure to sunlight or other forms of radiation (benign and malignant skin tumors)
Systemic disease (diabetes and Candida or tinea, hepatitis C, and cryoglobulinemia)
Use of medications (Stevens-Johnson syndrome, toxic epidermal necrolysis)
Travel history (Lyme disease, skin infections)
A negative history is as important as a positive history. The history of the particular skin lesions is also important, including time and site of initial appearance, spread, change in appearance, and triggering factors.
Dermatologic Examination
Visual inspection is the central evaluation tool; many skin disorders are diagnosed by the characteristic appearance or morphology of the lesions (see also Description of Skin Lesions). A full skin examination, including examination of the scalp, nails, and mucous membranes, is done to screen for skin cancers and to detect clues for the diagnosis of a widespread eruption. Magnification with a hand lens can help reveal morphologic detail. A hand-held dermatoscope with built-in lighting is particularly useful in evaluating lesions. Further information can be gathered by using diascopy or a Wood light.
