Complete loss of pigmentation in discrete patches, due to loss of epidermal melanocytes
M=F; peak age of onset 10-30 yrs; affects >1% of population.
Aetiology unknown, but may be autoimmune response against melanocytes (can be associated with thyroid disease and diabetes mellitus)
Varies widely in its presentation. Lesions can be single or multiple – typically have a well demarcated border.
Can also cause depigmentation of hair (leukotrichia).
Many inflammatory conditions can disrupt pigmentary system, especially if the dermoepidermal junction is involved hypopigmented patch colour often returns after several months
Rare autosomal recessive condition resulting in abnormal melanin synthesis – either a defect in the enzyme tyrosinase (decrease in melanin synthesis) or defect in packaging of melanin in melanosomes).