The history and physical examination are generally adequate for diagnosing many skin lesions. Some lesions require biopsy or further testing.
Distinct from many areas of medicine, the evaluation of dermatologic disease is often driven by morphology. Experienced clinicians frequently generate an initial morphologic differential diagnosis based on the appearance and distribution of skin lesions before obtaining the history. The subsequent history, physical examination, and, when indicated, laboratory or histopathologic evaluations obtained are then used to refine or narrow this differential diagnosis.
Dermatologic History
An initial history should include the history and appearance of particular skin lesions, including time and site of initial appearance, spread, change in appearance, and triggering factors.
Important additional information to obtain includes:
Personal or family history of skin conditions (eg, atopy, psoriasis) or skin cancers (melanoma)
Occupational exposures (contact dermatitis)
Long-term exposure to sunlight or other forms of radiation (eg, benign and malignant skin tumors, photosensitivity)
Systemic disease (eg, diabetes, lupus, other autoimmune diseases)
Sexual history (eg, syphilis, herpes simplex virus)
Use of medications (eg, Stevens-Johnson syndrome, toxic epidermal necrolysis, other drug rashes)
Travel history (eg, Lyme disease, skin infections)
A negative history is as important as a positive history.
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), which may vary across different skin tones.
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.
