How do you diagnose a pigmentation disorder?

The clinical history is the most important aspect of the investigation of a pigmentation disorder. It should focus on the time of onset (such as at birth, during childhood, or later in life) and a family history. Other facts to be determined include any associated illness or symptoms, drug ingestion, chemical exposure, occupation, and exposure to sunlight, artificial ultraviolet light, heat, or ionizing radiation. Finally, a careful review of systems should be performed, followed by a skin examination.