What is melanonychia?

• A. A condition of thickened nails
• B. A dark band within the nail plate due to increased pigmentation
• C. A nail fungus
• D. Ridges formed by aging

Answer: (B)

Melanonychia refers specifically to the presence of a dark band or streak within the nail plate. This condition occurs due to an increase in pigmentation, often caused by melanin deposition in the nail matrix. Factors that can lead to melanonychia include trauma, certain medications, or underlying medical conditions, and it can be benign or indicative of more serious health issues.

Understanding this, the other potential answers describe different nail conditions but do not accurately define melanonychia. Thickened nails and ridges associated with aging pertain to changes in nail texture or appearance, while nail fungus relates to a fungal infection affecting the nail. Melanonychia is distinct and characterized by the specific pigmentation changes within the nail, making option B the correct choice.