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Authors: Vanessa Ngan, Staff Writer, 2003. Updated: Dr Fleur Weiqian Kong, Honorary Dermatology Registrar, Mater Adult Hospital, Brisbane QLD, Australia; Dr James Muir, Dermatologist, Mater Adult Hospital, Brisbane QLD, Australia. Copy edited by Gus Mitchell. December 2020.
Onycholysis is a common nail disorder in which the nail plate has separated from the nailbed typically resulting in a well-defined area of white opaque nail. It may be idiopathic or secondary to trauma, skin disease, nail infections, tumours, or systemic events. Photo-onycholysis is due to ingestion of a photosensitiser, such as a medication [see Drug-induced photosensitivity].
Onycholysis can affect both sexes, all ages and races. It is most frequently seen in adult women.
Onycholysis can be primary (idiopathic, unknown cause) or secondary to one of many causes. Some examples are listed in Table 1.
Repetitive trauma, including manicure
|Infection||Dermatophytes and yeasts eg, T. rubrum, C. albicans
|Systemic disease||Endocrine eg, hypo- and hyperthyroidism, diabetes mellitus, pregnancy
Infiltrative eg, amyloidosis, sarcoidosis
Malignancy eg, multiple myeloma, Sezary syndrome
Photosensitivity eg, porphyrias
Yellow nail syndrome
|Medication||Drug-induced photosensitivity eg, antibiotics including tetracyclines, NSAIDs, psoralens, and oral retinoids
Chemotherapeutic agents eg, taxanes
|Others||Hereditary distal onycholysis (MIM 164800)|
Onycholysis can affect a single nail or multiple fingernails and/or toenails. The distal part of the nail is most commonly affected lifting the free edge; sometimes the nail may detach laterally or proximally. Oil spot sign is an island of onycholysis under a nail.
Clinical features can include the following signs.
Onycholysis in dermatoses
Onycholysis predisposes to secondary infection under the nail, most commonly with Candida albicans and Pseudomonas aeruginosa, resulting in discolouration of the nail.
Onycholysis can be cosmetically unacceptable, especially for people who work with their hands in public view.
Complications of onycholysis
Onycholysis is a clinical diagnosis with the cause often obvious on history and examination. Investigations may be required if the cause is not apparent.
Onycholysis may persist or progress due to:
Onycholysis should be distinguished from leukonychia (white nail), including Terry nail, in which the nail remains attached but appears white and opaque.
The detached portion of the nail will not reattach. The aim of treatment is for the new nail growth to remain attached to the underlying nailbed.
Specific treatment of onycholysis depends on the cause. This may mean ceasing or changing a medication, specific treatment of a nail infection, or appropriate treatment for an associated systemic condition or dermatosis.
Onycholysis of short duration and of known origin can recover with appropriate treatment. Fingernails take 4–6 months to fully regrow; toenails take twice as long. The longer onycholysis persists the less likely new nail growth will reattach due to permanent damage (cornification) of the underlying nailbed (‘disappearing nailbed’).
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