CONGENITAL ONYCHODYSPLASIA OF THE INDEX FINGERS

Congenital onychodysplasia of the index fingers, a condition characterized by hypoplasias and dysplasias of the nails peculiarly restricted to the index fingers, is assumed to be related to a peculiar grip of the thumbs leading to ischemia of the index fingers while the baby is in utero. This is based on our observation of a case two days after birth. Major characteristics of this condition, including index finger involvement and radial‐prone involvement of the nails, can be well explained by this hypothesis, as can exceptional cases of middle finger involvement. A case of acquired polyonychia is presented which also appears to favor the ischemia theory for this condition.