Melanosis(redirected from melanosis of the iris)
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the intensified formation and deposit in organs and tissues of a dark brown or black pigment of the melanin group (normally present in the skin, retina, and meninges).
A distinction is made between congenital melanosis and acquired melanosis. The former includes congenital melanosis of the skin (melanoderma), manifested by freckles or pigmented birthmarks. Acquired melanosis frequently develops as a result of a change in endocrine function (adrenal, pituitary, or gonadal). The pigmentation may be diffuse (for example, in Addison’s disease) or circumscribed (for example, during pregnancy, on the face and around the nipples). The condition may also be caused by systemic poisoning by hydrocarbons (toxic melanoderma) or by physical, mechanical, or chemical irritation (light, heat, the distillate products of coal).