Disorders of Pigmentation
Vitiligo causes irregular, completely depigmented skin patches.
DISORDERS OF PIGMENTATION
Vitiligo causes irregular, completely depigmented skin patches. It is common and can affect any race; there may also be a familial predisposition. The disease has an unknown aetiology that is possibly autoimmune. Microscopically, affected areas are devoid of epidermal melanocytes.
Melasma causes irregular blotchy patches of hyperpigmentation on the face; it is associated with sun exposure, oral contraceptive use, and pregnancy (“mask of pregnancy”) and may regress after pregnancy.
Freckles (ephelides) are light brown macules on the face, shoulders, and chest. They are common in fair-skinned children and tend to darken and fade with the seasons due to sunlight exposure. Microscopically, freckles are characterized by increased melanin deposition in the basal cell layer of the epidermis with a normal number of melanocytes.
Benign lentigo is a localized proliferation of melanocytes that cause small, oval, light-brown macules. Microscopically, benign lentigos show linear melanocytic hyperplasia.