Familial median canaliform nail dystrophy.

Median canaliform nail dystrophy typically appears as a central nail groove, beginning at or distal to the proximal nail fold, from which small lateral fissures may be found. Although the onset of this nail dystrophy has occasionally been associated with either prior local trauma or the initiation of treatment with isotretinoin, the etiology of this condition remains elusive for most affected individuals. We describe a man with median canaliform nail dystrophy whose brother and mother had the same nail dystrophy, review the other reported cases, and discuss the differential diagnosis of this nail disorder.