Ectopic nails (onychoheterotopia) are a rare condition when an additional and independent nail is located in an abnormal site. More cases have been described in the literature as affecting the hands than the feet.
Present with a deviant outgrowth that resembles a nail plate.
Two types: Associated with a history of trauma and not associated with a history of trauma (indicating genetic predisposition).
Pathogenesis is not clear, but could be related to:
- ectopic existence of germ cells
- transfer and inoculation of oncocytes from traumatic event
- seen in some hereditary condiitons and reports of familial occurrences
- may be some sort of dyskeratosis of the skin that has grown into a nail unit
Differential Diagnosis: Heloma durm (hard corns); Durlacher’s corn; Listers corn; foreign body
Treatment:
Surgical excision followed by phenol chemocautery on the nail matrix.
Commentary:
- Paper by Ena et al (2015) reported on 22 ectopic foot nails, but as identified here, the images of what they called ectopic nails were really hard corns (heloma durum)
Images from Ina et al (2015) paper in which the incorrectly identified the above as ectopic nails, when they are hard corns (heloma durum).
Related Topics:
Onychoheterotopia
External Links:
Ectopic Foot Nails (Podiatry Arena)
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