Discussion :
Half and half nail also known as Lindsay’s nail was first described by Lindsay in 1967 (1). Clinically, it shows as a nail with white proximal portion and reddish brown or pink distal portion, with a sharp demarcation line between the two portions, which usually remains parallel to the distal free margin of the nail. It is a rare clinical finding, but it can be frequently seen in chronic renal failure. It can also appear in yellow nails syndrome, Crohn’s disease, Kawasaki’s disease, Behcet’s disease, cirrhosis, hyperthyroidism, zinc deficiency, citrullinemia, pellagra and HIV infection (2).
During the COVID-19 pandemic, several cutaneous manifestations have been reported. Recently ; nail changes started getting attention, beginning with transverse leukonychia (Mees lines) (3) ; to red half-moon nail sign (4) and Beau lines (5). These nail alterations can be explained by keratinization anomalies of nail tablet associated to vascularization alterations of nail bed. A transient matrix injury caused by COVID-19 infection is suggested.