Red lunulaeL60.8

The lunula is the white crescent-shaped area at the base of the fingernails and toenails and the only visible part of the nail matrix.

A red lunula can occur as a complete homogeneous discoloration (the entire lunula is red), as an incomplete variant (only the proximal lunula is red), or as a speckled, spot-shaped form.

Red lunula is associated with a number of dermatological and systemic diseases. It is one of the rarer manifestations of lichen planus (LP): Furthermore, the occurrence of red lunulae has been associated with the following diseases:

• Systemic lupus erythematosus (diffuse form of red lunulae).
• Alopecia areata
• Heart failure
• Cirrhosis of the liver
• Psoriasis (punctate form of red lunulae)
• Rheumatoid arthritis (Jorizzo JL et al. 1983)
• Carbon monoxide poisoning
• Twenty-nail dystrophy (Twenty-nail dystrophy)
• Malignant lymphatic systemic diseases

No evidence of neovascularization.

Red lunulae are thought to result from increased arteriolar blood flow, a vasodilator capacitance phenomenon, or changes in the optical properties of the overlying nail so that normal blood vessels are more prominent. See also under erythronychia (red nail).

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2. Chelidze K et al (2018) Nail changes in alopecia areata: an update and review. Int J Dermatol 57:776-783.
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5. Jorizzo JL et al (1983) Red lunulae in a patient with rheumatoid arthritis.
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