The half-and-half nail: a new sign of Crohn's disease? Report of four cases.

Systemic disease can produce changes in the nails. Perhaps the best known example of this is koilonychia as a sequale of iron deficiency anemia. "Half and half nail" is a type of pseudoleuconychia that can be caused by chronic renal disease, Kawasaki's disease, cirrhosis, and zinc deficiency. It has not been described in patients with Crohn's disease yet. Four male patients with Crohn's disease were observed. None of them had extraintestinal manifestations of Crohn's disease. The average duration of the disease was 5.25 (range, 1-10) years. The nail alterations were defined with a portion of the nail being as much as 15 to 40 percent of normal color distally, whereas the rest of the nail was white. The contrast between the two zones remains sharply demarcated even after constricting venous return. Histologic examination was not performed. Every patient had zinc deficiency but not hypalbuminaemia or sideropenia. After review of relevant literature (MEDLINE, PubMed, etc.), we found that half-and-half nail had not been described in Crohn's disease. This study was designed to highlight the fact that the half-and-half nail, which was thought to be a sign of chronic renal failure, also occurs in patients with Crohn's disease. The relationship of this symptom to clinical activity cannot yet be assessed and has only been observed in four cases.