Diagnosis

The first step of any contact with a doctor is the medical history. In order to classify a cuteous eruption, a dermatologist will ask detailed questions on the duration and temporal pattern of skin problems, itching or pain, relations to food intake, sunlight, over-the-counter creams and clothing. When an underlying disease is suspected, a more detailed history of related symptoms might be elicited (such as arthritis in a suspected case of lupus erythematosus).

Physical examination is generally under bright light and involves the whole body. At this stage, the doctor may apply Wood's light, which may aid in diagnosing types of mycosis, or a dermatoscope, which enlarges a suspected lesion and may help differentiating lesions, e.g. between a naevus from melanoma. A morphological classification of dermatological lesions is critical to being able to diagnosis dermatological disorders.

Dermatology has the benefit of having easy access to tissue for diagnosis. Culture or Gram staining of suspected infectious lesions may identify a pathogen and help direct therapy.

If the diagnosis is uncertain, or cutaneous malignancy is suspected, a small punch-hole biopsy can be taken under local anesthetic, to be examined by a specialist of histopathology.