What is the discoloration of skin and nails called?

Dyschromia refers to any abnormality in the color of the skin or nails. This term encompasses a variety of conditions where discoloration can manifest as either excess pigmentation, leading to darker areas, or loss of pigment, resulting in lighter areas. It effectively captures the broader spectrum of skin and nail discoloration, making it the most accurate choice in the context of the question.

Hyperpigmentation specifically refers to darker patches of skin due to excess melanin production, while vitiligo describes a condition that causes patches of skin to lose pigment entirely due to the destruction of melanocytes. Leukoderma also implies a loss of pigment but is often used in specific contexts, such as describing lighter skin areas resulting from various conditions. Thus, while all of these terms relate to skin discoloration in different ways, dyschromia is the term that most comprehensively covers the abnormal color changes in both skin and nails.