What are the tests that indicate hypopigmentation?

Observation: If there are areas of lighter pigmentation adjacent to or surrounded by normal pigmentation, the lighter areas are hypopigmented.

Light skin spots: Hypopigmentation or light skin spots, may be diagnosed easily in the office by a machine called a woods lamp. This is like a "black light". Causes of hypopigmentation are a decrease of melanin, melanocytes or the Amino Acid tyrosine. Sometimes a fungus of the skin may cause hypopigmentation so a simple culture of the skin can diagnose the cause. Complete loss of skin pigment is called vitiligo.