The most important part of the workup consists of appropriately collected and examined fungal samples.
The diagnosis or exclusion of onychomycosis is important because many nail disorders resemble Fungal Infections. Onychomycosis requires long treatment, which should be preceded by taking microbiological samples to confirm the diagnosis.
Nail disorders are common in the aged, particularly, and may cause functional problems.
Many nail disorders are resistant to treatment. This applies particularly to age-related nail dystrophy.
Examination of the nails may provide diagnostic clues in patients with skin symptoms of unknown origin.
General
Anatomically, the hyponychium (epidermis beneath the nail), nail plate, lunula, nail bed, nail matrix (or root), nail pocket, cuticle and nail fold are usually distinguished.
Nails are primarily there to protect the tips of the fingers and toes but they also have functional tasks: for instance, they may be helpful in picking up tiny objects.
Mean growth rates: fingernails approx. 3 mm/month, toenails approx. 1 mm/month. Any effect on nails and any therapeutic response are therefore seen with a delay of several weeks or months.
With advanced age, nails undergo individual changes and the prevalence of nail problems increases.
Most common nail problems
Age-related nail dystrophy, or ”brittle nail syndrome”: longitudinal grooves, thickening, unevenness, layered transverse or longitudinal splitting, disappearance of the lunula, etc.; picture 1
Age-related changes to nails may begin to take place in early adulthood. The line between such changes and normal nails is thin and the changes also depend on heredity.
Onychomycosis Dermatomycoses: common in toenails but may also occur in fingernails
Chronic irritation of nails and nail folds, chronic paronychia Paronychia and Ingrown Toenail (wet work, cosmetics, artificial nails) may lead to nail dystrophy (picture 2).
Repeated mechanical irritation (e.g. poorly fitting shoes, sports, running, other hobbies) or manipulation (e.g. manicure, long nails, nail biting or picking; picture 3) may damage nails (e.g. splitting the nail longitudinally, causing leukonychia, or white spots and lines; picture 4) or cause slight detachment of the tip of the nail (onycholysis; picture 5).
Toenails may grow thicker, crooked or claw-like (onychogryphosis; picture 6) in association with recurrent trauma, less frequent nail care or circulatory problems of the lower limbs Lower Limb IschaemiaTreatment of the Diabetic Foot.
Skin disorders occurring close to the nails (e.g. hand eczema Hand Dermatitis, psoriasis of the hands or fingertips) may cause nail lesions (transverse grooves, or so-called washboard nails; pictures 78).
Certain disorders may still cause nail dystrophy even if the affected skin areas are elsewhere on the body and not close to the nails.
Psoriasis Psoriasis: distal detachment of the nail (picture 9), subungual hyperkeratosis (picture 10), nail pitting or yellowish-brown spots known as oil spots (picture 11)
Dermatomyositis and lupus erythematosus Discoid Lupus Erythematosus: dilated blood vessels in nail folds, tenderness of nail folds, nail dystrophy, transverse lines
Photodermatitis, such as phototoxic drug reaction Photodermatitis: some time after such reactions, nails may become detached, which is called photo-onycholysis
Rare causes
Children and young adults rarely have idiopathic nail dystrophy, which may be limited (e.g. in both first toe nails) or present in all nails (trachyonychia, twenty nail dystrophy; pictures 1314).
Median canaliform nail dystrophy: uni- or bilateral deep longitudinal nail grooves, either idiopathic or due to manipulation or irritation; pictures 1516
Rare hereditary nail dystrophies that may be associated with nail, hair, mucosal and/or skin changes (e.g. pachyonychia congenita)
Nail lesions in association with systemic diseases
More or less typical nail lesions occur in patients with certain systemic diseases. They are as such not diagnostic for any disease and should always be assessed in the light of other symptoms and examinations.
Severe infections, cytotoxic therapy, poisoning: leukonychia, transverse lines, white transverse lines, so-called Beau lines (picture 17), other forms of nail dystrophy, nail lesions appear with delay.
Chronic lung disorders, such as severe chronic obstructive pulmonary disease: nail clubbing (picture 18), bulbous enlargement of the distal phalanges, whiteness of the proximal nail
Hand-foot-and-mouth disease Enterovirus Infections: after recovery, detachment (onychomadesis) of the proximal nail and/or other nail dystrophy may occur
Gastrointestinal disorders, particularly severe cases, such as malabsorption: transverse grooves, white transverse lines, spoon nails, or koilonychia (picture 19)
Hepatic disorders, particularly cirrhosis: leukonychia, whiteness of the proximal nail, missing lunula, Terry's nails
Renal disorders, such as chronic renal failure requiring dialysis, state following renal transplantation: sharply demarcated whiteness of the proximal nail and erythema of the distal nail, i.e. half-and-half nails, missing lunula, leukonychia
Many pharmaceuticals may cause nail lesions (Beau lines, onychomadesis, melanonychia, onycholysis and pyogenic granulomas).
Immunosuppressive drugs, cancer therapies and retinoids, for example, may cause recurrent paronychia (picture 28.
Dystrophy of individual nails
In the case of slowly worsening dystrophy of an individual nail, nail bed tumours, such as fibrokeratoma, glomus tumour (picture 20) and Koenen's tumour (picture 21) and bone tumours (such as subungual exostosis, picture 22) should be excluded.
Warts (pictures 2425), myxoid cysts (mucous cysts; picture 26) and pyogenic granulomas (picture 27) typically occur in the nail fold area and close to the nails.
If chronic erythema, scaling or ulceration occurs in a single nail fold and/or tip of a single finger, skin malignancies (Bowen's disease, keratoacanthoma, acral melanoma) should be excluded by skin biopsy.
Discolouration of nails
External discolouration is easy to show by scraping the nail with a sharp object. The colour will come off without damaging the surface of the nail (e.g. the yellowish brown tar colour in smokers, self-tanning ointments, conditioners).
Onychomycosis may colour the nail white (superficial onychomycosis; picture 29) or dark (picture 30).
Colonization with the fungal mould Aspergillus may cause black spots in the nail resembling haematoma or onychomycosis but such spots are most often due to some other process damaging the nail, such as mechanical irritation.
Colonization with Pseudomonas bacteria may colour the nail green (picture 31) but even in this case the colour is usually due to some other process damaging the nail.
Melanin from a pigmented naevus beneath a nail usually forms one longitudinal dark line in the nail. The change is benign but, at least when occurring as a new symptom, it may require exclusion of melanoma by biopsy. People with black or dark skin have such lines physiologically Skin Problems in People with Dark Skin.
Haematomas due to trauma can often be seen beneath nails.
Yellow nails are due to thickening of the nail plate and seen in age-related nail dystrophy. They may sometimes be due to poor blood or lymph circulation (e.g. lymphoedema).
White spots or lines in a nail (leukonychia, picture 4) are common and usually resolve spontaneously. In some cases they may be signs of a transient developmental disorder of the nail and may be due to various factors (mechanical trauma, systemic infections, etc.).
Workup
In undefined nail dystrophy, the most important examination is to take an untreated fungal sample for microscopy and culture it or perform a PCR (nucleic acid detection) test.
It is important to make sure that the patient has not taken any antifungal medicines recently (topical ointments within the last 2 months, medicated nail lacquer within the last 2 months or oral antifungal medicines within the last 6 months) and that the sample is representative and correctly taken. Several samples can be taken, as necessary. Any antifungal drugs taken do not affect a nucleic acid detection test.
Skin biopsy (to exclude malignancy) is useful only if there is a tumour beneath a nail or if there are circumscribed, erythematous, scaly lesions.
After nerve block anaesthesia, the nail plate is excised from the sampling area, as for phenolization Paronychia and Ingrown Toenail. Another option is to bisect the nail longitudinally all the way to the nail fold. For biopsy, the nail plate is lifted and a representative tissue sample taken from beneath the nail with a knife or cutaneous punch. A third option is to first punch the nail plate with a larger punch (e.g. 5 mm) and then take a biopsy sample from the nail bed area with a smaller punch (e.g. 3-4 mm). The wound from any of these procedures can usually be allowed to heal without suture.
Treatment
In age-related nail dystrophy, patients may benefit from regular use of a non-medicated ointment on nail and nail fold areas. Oral biotin, for instance 5 mg once daily for 3 months, has also been used.
There is no evidence for the efficacy of other vitamins or trace elements.
Regular use of a non-medicated fatty ointment helps to treat lesions caused by mechanical or other chronic irritation.
Treatment by a chiropodist helps with severely deformed nails (mechanical treatment, urea treatment).
Ram's horn nails (onychogryphosis) can be shortened or thinned using strong cutting forceps (rongeur).
In onychomycosis restricted to the tip of the nail, lengthy topical treatment of 6 to 12 months (amorolfine, ciclopirox, tioconazole) may help. In more severe forms, systemic treatment of 3 to 4 months is usually needed Dermatomycoses.
Nail lesions due to systemic diseases often resolve when the patient recovers from the underlying disease. The same symptomatic treatment as for age-related nail dystrophy can be tried.
In nail discolouration, it is most important to reduce the process damaging the nail (e.g. mechanical irritation). Local antibacterial (e.g. clindamycin) or antifungal drugs (e.g. ketoconazole) can be tried to treat Aspergillus or Pseudomonas colonization, administered first once or twice daily for 2 to 3 weeks and then 2 to 3 times weekly for 1 to 3 months, for example.
Successful treatment of skin disorders in the vicinity of nails (e.g. chronic hand eczema or paronychia) will cure nail lesions, as well (with a delay of several months).
Nail lesions associated with psoriasis are often difficult to treat.
Intermittent treatment of 1 to 2 months with a class III or IV topical corticosteroid solution or ointment that is used for nail folds may be effective for psoriatic nails, as well.
A dermatologist may order oral medication for severe psoriasis (also affecting areas other than the nails).
If the patient has severe refractory nail problems that cause functional problems, consult a dermatologist.
References
Abdullah L, Abbas O. Common nail changes and disorders in older people: Diagnosis and management. Can Fam Physician 2011;57(2):173-81. [PubMed]
Rotta I, Sanchez A, Gonçalves PR et al. Efficacy and safety of topical antifungals in the treatment of dermatomycosis: a systematic review. Br J Dermatol 2012;166(5):927-33. [PubMed]
Zaiac MN, Walker A. Nail abnormalities associated with systemic pathologies. Clin Dermatol 2013;31(5):627-49. [PubMed]
Eisman S, Sinclair R. Fungal nail infection: diagnosis and management. BMJ 2014;(348):g1800. [PubMed]
Dehavay F, Richert B. Nail is Systemic Disorders: Main Signs and Clues. Dermatol Clin 2021;39(2):153-173. [PubMed]