melanosis

Abnormal dark brown or brown-black pigmentation of various tissues or organs, as the result of melanin or, in some situations, other substances that resemble melanin to varying degrees; e.g., m. of the skin may occur in widespread metastatic melanoma, sunburn, during pregnancy, and as a result of chronic infections. [melano- + G. -osis, condition]

- m. coli m. of the large intestinal mucosa due to accumulation of pigment of uncertain composition within macrophages in the lamina propria.

- neurocutaneous m. cutaneous giant pigmented nevi associated with m. of the leptomeninges; malignant melanomas may develop in the skin or meninges.

- oculodermal m. pigmentation of the sclera and skin around the eye, usually unilateral; seen especially in women of Asian descent. SYN: Ota nevus.

- pustular m. a transient, benign, pustular rash of unknown etiology seen in neonates; leaves a hyperpigmented base when the pustule resolves.

- Riehl m. a brown pigmentary condition of the exposed portions of the skin of the neck and face with melanin pigment in dermal macrophages, thought to result from photodermatitis due to materials, such as cosmetic ingredients, or oils encountered in various occupations.

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mel·a·no·sis .mel-ə-'nō-səs n, pl -no·ses -'nō-.sēz a condition characterized by abnormal deposition of melanins or sometimes other pigments in the tissues of the body

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n.

1. see melanism.

2. a disorder in the body's production of the pigment melanin.

3. cachexia associated with the spread of the skin cancer melanoma.

• melanotic adj.

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mel·a·no·sis (mel″ə-noґsis) [melan- + -osis] excessive pigmentation of part of the body owing to a disturbance in melanin pigmentation; called also melanism.