discolorations

Discolorations refer to any alteration in color that deviates from the normal appearance of a surface, tissue, or object. They may be transient or permanent and can arise from chemical, biological, physical, or environmental factors.

In human health, skin and mucous membranes commonly exhibit discoloration. Hyperpigmentation involves excess pigment (melanin), producing brown to black patches; hypopigmentation involves reduced pigment, leading to lighter areas. Vascular discolorations reflect changes in blood flow or oxygenation, such as erythema (redness), cyanosis (bluish), or jaundice (yellowing due to bilirubin). Discoloration can result from inflammation, trauma, medications, hormonal changes, infections, or systemic diseases.

Other color changes include carotenoid-related yellowing (carotenemia) and metabolic or genetic conditions such as ochronosis or alkaptonuria, which can produce bluish-black or other unusual hues. Light exposure, aging, and infections are common non-pathologic or secondary causes.

Beyond the body, discoloration affects materials, artworks, and documents. Oxidation, ultraviolet exposure, chemical stains, heat, or contamination can alter the color of metals, textiles, wood, paper, and pigments. In conservation and restoration, discoloration is a key diagnostic sign of aging and environmental damage.

Assessment involves history, examination, and sometimes laboratory tests. Management targets the underlying cause and may include sun protection, topical therapies, laser or surgical options for skin conditions; for materials, stabilization, cleaning, protective coatings, or professional restoration.

Discoloration is a broad concept used across medicine, materials science, and conservation to describe color changes and their implications for health, aesthetics, and longevity.