The Half-and-Half Nail

Abstract

That temperamental dignotions, and conjecture of prevalent humours, may be collected from spots in our nails, we are not averse to concede. —Sir Thomas Browne IT HAS long been appreciated that systemic disease can produce changes in the nails. Hippocrates, in his classic description of the clubbing phenomenon in empyema, first directed attention to the systemic onychopathies. A relative spate of descriptive reports in more recent times was begun by J. C. Reil's 1792 notation on white transverse bands and sulci following febrile diseases.¹Gradually, such entities as Beau's lines,²Mees' lines,³splinter hemorrhages,⁴koilonychia,⁵pigmented nails,⁶onycholysis,⁷Terry nails,⁸Muehrcke's striae,⁹azure lunulae,¹⁰rubra lunulae,¹¹platonychia,¹²the nail-patella syndrome,¹³and the yellownail syndrome,¹⁴came to be recognized as nail signs of diagnostic significance. There are now more than 40 described onychopathies due to systemic illnesses and three monographs focusing on the nails in disease.¹⁵¹⁷ That certain nail