A slight convex curve at the nail angle where the nail meets the skin, measuring about 160 degrees, is most appropriately described as which finding?

• A. Normal finding
• B. Clubbing
• C. Koilonychia
• D. Onychomycosis

Answer: (A)

Normal nail curvature is described by the proximal nail angle, the angle between the nail plate and the surrounding skin. In a healthy nail this angle is about 160 degrees, so a slight convex curve around 160 degrees is a typical normal finding. When clubbing develops, this angle increases beyond 180 degrees and the nail bed becomes more curved, often with fingertip changes. Koilonychia refers to spoon-shaped nails from thinning of the nail plate, not the angle at the nail base, and onychomycosis causes nail thickening, discoloration, and brittleness rather than a normal angular description.