Posttraumatic Ectopic Nail

793 nail unit separate from the normal one. There was no adhesion between the ectopic and normal nail units. Thus, using a No. 15 blade, we successfully removed the ectopic nail plate including its matrix en bloc (Fig. 2A, B). On histopathology, the nail bed was slightly stained with the hematoxylin-eosin (H&E) dye. In addition, there was an underlying presence of the nail matrix without a granular layer. Based on these findings, the patient was diagnosed with posttraumatic ectopic nail (Fig. 2C). At the most recent follow-up (6 months), it was determined that the patient had undergone an uneventful course without recurrent episodes or complications. Ectopic nail, also termed onychoheterotopia, is a pathologic condition characterized by the persistent growth of the ectopic nail plate due to the presence of the ectopic nail matrix in other regions than the normal nail bed. Little is known about the exact pathogenesis of ectopic nail, for which various hypotheses have been proposed. According to Ohya et al., an ectopic nail is a teratoma that is formed by stray germ cells (cited in Jeong et al. [2]). According to Kikuchi et al. [4], the pathogenesis of ectopic nail is closely associated with rudimentary nail or hidden polydactyly. According to some reports, it is associated with congenital palmar nail syndrome, Pierre Robin syndrome, or the aberration of the long-arm of chromosome 6. This provides a possibility that its pathogenesis might have a familial tendency or genetic inheritance. On the other hand, posttraumatic ectopic nail may occur as a result of acute single overwhelming injury or chronic repeated minor injury. That is, posttraumatic ectopic Posttraumatic Ectopic Nail