Polyonychia also known as supernumerary nails is a condition in which two or more nails grow in the same finger or toe.[2]

Polyonychia
Other namessupernumerary nails of the fingers and toes
Polyonychia from congenital polysyndactyly
SpecialtyMedical genetics
SymptomsHaving two or more finger/toenails on a single digit
ComplicationsSocial insecurity
Usual onsetBirth (congenital), post-traumatic (acquired)
DurationLife-long (unless it's corrected)
TreatmentPlastic surgery
PrognosisGood
Frequencypolydactyly: 1 in 500-1,000 live births[citation needed] syndactyly: 1 in 2,500-3,000 births[1]
DeathsNone

Signs and symptoms

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The signs/symptoms of polyonychia are very easy to detect: two or more nails growing on the same finger or toe.

The nails can either be separate, small nails (micronychia) or one wide, almost complete nail, the digit affected could also be wider than normal

Causes

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Polyonychia is generally caused by a congenital duplication of the distal phalange of the affected digit(s), this can be caused by congenital factors (sporadic without a genetic link) or by genetic factors (sporadic or familial with genetic link).

It can also be caused by polysyndactyly, which is characterized as one normal digit being connected/webbed (syndactyly) to an extra digit (polydactyly).

Polyonychia can also be acquired, such as after an accident that affected the nail bed causing it to split. This type of polyonychia is just referred to as "post-traumatic split nail" [3]

Polyonychia's syndromic causes include:

  • Isolated congenital onychodysplasia[4]

Polyonychia's non-syndromic causes include:

  • Polyphalangism (more specifically of the distal phalange)[5]
  • Polysyndactyly

See also

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References

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  1. ^ "Syndactyly: Practice Essentials, Etiology, Epidemiology". 17 February 2022.
  2. ^ "Definition of polyonychia | Dictionary.com". www.dictionary.com. Retrieved 2022-04-10.
  3. ^ Lade, Nitin Ramchandra; Jain, Divya Bimit; Singh, Adarsh Lata (2012-06-01). "Post-traumatic acquired polyonychia: A rare occurrence". Dermatology Online Journal. 18 (6): 10. doi:10.5070/D30755b6jk. PMID 22747934.
  4. ^ RESERVED, INSERM US14-- ALL RIGHTS. "Orphanet: Isolated congenital onychodysplasia". www.orpha.net. Retrieved 2022-04-10.{{cite web}}: CS1 maint: numeric names: authors list (link)
  5. ^ Knipe, Henry. "Duplicated distal phalanx of great toe | Radiology Case | Radiopaedia.org". Radiopaedia. Retrieved 2022-04-10.