Beau lines

Transverse depressions of the nail plate resulting from temporary interruption of proximal nail matrix proliferation, typically presenting as bilateral, horizontal grooves on fingernails or toenails and serving as a marker of prior systemic illness, severe local trauma, or other significant physiologic stress.

Causes

• Acute physical trauma to the nail matrix

• Severe systemic illness: Pneumonia, measles, mumps

• Medication toxicity (chemotherapy)

• Nutritional deficiencies (protein or zinc)