Red lunulae are associated with rheumatoid arthritis, systemic lupus erythematosus, alopecia areata, cardiac failure, hepatic cirrhosis, lymphogranuloma venereum, psoriasis, carbon monoxide poisoning, twenty-nail dystrophy, and reticulosarcoma. We examined four patients with red lunulae. Three had chronic obstructive pulmonary disease. Two of these three were alcohol abusers and were without any of the conditions previously associated with red lunulae. Two of the four also had palmar erythema. Histopathologic examination of the red lunula in one of the four cases did not show signs of neovascularization. We report our findings in these patients, which suggest that red lunulae result from increased arteriolar blood flow, a vasodilatory capacitance phenomenon, or changes in the optical properties of the overlying nail so that normal blood vessels become more apparent.
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