Nail changes

Nail changes are abnormalities of the nail plate, matrix, bed, folds or surrounding tissue.

Nail unit. The matrix produces the plate (proximal matrix forms the dorsal plate, distal matrix the ventral). The nail bed holds the plate, the hyponychium seals the free edge, and the proximal fold and cuticle protect the matrix. Fingernails grow about 3 mm each month and are replaced in 4 to 6 months. Toenails grow about 1 mm each month and are replaced in 12 to 18 months.

Classification by site of disease

• Matrix: pitting, ridging, Beau lines, onychomadesis, trachyonychia, nail thinning, longitudinal melanonychia, leuconychia (true), and onychorrhexis.
• Nail bed: onycholysis, subungual hyperkeratosis, splinter haemorrhages, oil drop sign, apparent leuconychia and Terry nails.
• Nail folds: paronychia (acute and chronic), pterygium, nail fold telangiectasia and cuticle changes.
• Whole unit: clubbing, koilonychia, Lindsay nails, yellow nail syndrome, green nail and nail loss.

Classification by number. One digit points to local causes: trauma, tumour, infection, wart or a cyst. Several or all nails point to systemic, inflammatory or drug related causes.

Classification by colour

• White: true leuconychia (matrix), apparent leuconychia (bed: Terry nails, Muehrcke lines), punctate leuconychia (trauma).
• Yellow: onychomycosis, yellow nail syndrome, psoriasis, tetracycline.
• Green: Pseudomonas infection of an onycholytic nail.
• Brown and black: longitudinal melanonychia (benign activation, naevus, lentigo, melanoma), subungual haematoma, drugs, Addison disease and fungal infection.
• Blue: argyria, minocycline, Wilson disease (azure lunulae), antimalarial drugs.
• Red: red lunulae (heart failure, connective tissue disease), splinter haemorrhages, subungual glomus tumour.

Key distinctions. A single pigmented streak in a digit in an adult needs exclusion of melanoma. Nail pitting with oil drop discolouration suggests psoriasis. Onycholysis with subungual hyperkeratosis in a toenail suggests onychomycosis, though psoriasis can mimic it. New clubbing may signal lung cancer, endocarditis or inflammatory bowel disease.

History

• Onset, tempo, number of nails affected, progression, pain, bleeding, discharge, swelling, itch.
• Trauma, including repetitive trauma from footwear, running and manicure, occupational wet work, detergents, artificial nails and chemical exposure.
• Psoriasis, eczema, lichen planus, alopecia areata, fungal skin infection (tinea pedis), diabetes, peripheral arterial disease, Raynaud phenomenon, thyroid disease, kidney or liver disease, HIV, immunosuppression.
• Systemic symptoms: fever, weight loss, cough, breathlessness, joint pain, rash, diarrhoea, oedema, fatigue.
• Drugs: chemotherapy (taxanes, cyclophosphamide, anthracyclines), EGFR inhibitors and other targeted agents, retinoids, tetracyclines (photo-onycholysis), antimalarials, hydroxycarbamide, zidovudine, anticoagulants, beta blockers, lithium, gold, penicillamine and antithyroid drugs.
• Family history of nail disease, melanoma or skin cancer.
• Habits: nail biting, picking and cuticle manipulation.
• For pigmented lesions: duration, change in width, colour or shape, previous trauma, personal and family history of melanoma.

Examination

• Examine all 20 nails, nail folds, hyponychium and surrounding skin. Photograph with a ruler.
• Plate: surface (pitting, ridges, grooves), thickness, colour, shape (spoon, curved, clubbed), attachment.
• Bed: onycholysis, debris, haemorrhages, nodules.
• Folds: erythema, swelling, tenderness, pus, loss of cuticle.
• Longitudinal pigmentation: width (over 3 mm raises concern), colour variation, blurred borders, pigment extension onto the proximal or lateral nail fold (Hutchinson sign), change in width of the band, nail dystrophy.
• Clubbing: loss of the nail fold angle (Lovibond angle over 180 degrees), Schamroth sign (loss of the diamond window on opposing distal phalanges), bulbous pulp.
• Skin and mucosa: psoriasis plaques, lichen planus (violaceous papules, oral Wickham striae), eczema, scalp changes, tinea pedis.
• Hands: sclerodactyly, Raynaud signs, nail fold capillary abnormalities, Osler nodes and Janeway lesions, joint swelling.
• Pulses, capillary refill and signs of peripheral arterial disease.
• Cardiac murmur, lung signs, lymph nodes, hepatosplenomegaly, thyroid and signs of chronic liver or kidney disease.
• Dermoscopy of the nail plate and nail fold.

Red flags

• Longitudinal melanonychia affecting a single digit in an adult, with width over 3 mm, widening, irregular colour or Hutchinson sign.
• Nonhealing nail ulcer, bleeding nodule, nail destruction or a persistent nail bed lesion (squamous cell carcinoma, amelanotic melanoma).
• Rapid onset clubbing, or clubbing with weight loss, haemoptysis or bone pain.
• Splinter haemorrhages with fever, new murmur or Janeway lesions (infective endocarditis).
• Painful, tender purple subungual lesion (glomus tumour), with cold sensitivity.
• Acute paronychia with abscess, fever, or spreading erythema or signs of flexor tenosynovitis.
• Digital ischaemia, nail fold infarcts or gangrene (vasculitis, embolism, scleroderma).
• Beau lines or onychomadesis in several nails after a severe illness, or Mees lines after poisoning or kidney failure.
• Subungual haematoma with distal phalanx fracture or nail bed laceration.
• Nail changes in an immunosuppressed patient with spreading infection.

Special groups

• Children: trachyonychia, nail biting, congenital nail disorders, habit tic deformity, and ingrown toenail are common. Onychomycosis is uncommon. Beau lines may follow hand foot and mouth disease.
• Pregnancy: avoid oral terbinafine, azole antifungals and griseofulvin. Use topical therapy.
• Older adults: onychogryphosis, onychomycosis, dystrophy from trauma and vascular disease are frequent, and toenail care affects walking.
• Diabetes and peripheral arterial disease: nail disease can precipitate ulceration and infection, so foot examination is required.
• HIV infection: proximal subungual onychomycosis is a marker of immunosuppression.
• Dark skin: multiple longitudinal pigmented bands are common and usually benign, but a single new band, a band that changes, or Hutchinson sign needs biopsy.
• Region specific: tinea unguium, subungual tungiasis, and leprosy related nail change.

Infective

• Onychomycosis (dermatophyte, yeast and nondermatophyte mould).
• Acute bacterial paronychia (Staphylococcus aureus, streptococcus).
• Chronic paronychia (Candida and irritant).
• Green nail syndrome (Pseudomonas aeruginosa).
• Viral periungual and subungual warts.
• Herpetic whitlow.
• Subungual tungiasis.
• Syphilitic nail changes.
• Leprosy.

Inflammatory dermatoses

• Nail psoriasis.
• Nail lichen planus.
• Nail eczema and contact dermatitis.
• Alopecia areata (pitting, trachyonychia).
• Lichen striatus.
• Darier disease.
• Reactive arthritis and keratoderma blenorrhagicum.
• Pemphigus and pemphigoid.

Traumatic and mechanical

• Subungual haematoma.
• Nail bed laceration or avulsion.
• Ingrown toenail.
• Onychocryptosis and pincer nail.
• Habit tic deformity and nail biting.
• Repetitive trauma, including tight footwear and running.
• Median canaliform dystrophy.
• Onychogryphosis.

Tumours and cysts

• Subungual melanoma and nail matrix melanoma.
• Melanocytic naevus and lentigo of the nail matrix.
• Subungual and periungual squamous cell carcinoma and Bowen disease.
• Glomus tumour.
• Digital mucous (myxoid) cyst.
• Subungual exostosis.
• Onychomatricoma and onychopapilloma.
• Pyogenic granuloma.
• Periungual fibroma (tuberous sclerosis).
• Metastasis to the distal phalanx.

Nail signs of systemic disease

• Clubbing: lung cancer, bronchiectasis, lung abscess and empyema, interstitial lung disease, cystic fibrosis, cyanotic congenital heart disease, infective endocarditis, inflammatory bowel disease, cirrhosis, thyroid acropachy, hereditary.
• Koilonychia: iron deficiency, haemochromatosis, trauma and occupational exposure.
• Splinter haemorrhages: infective endocarditis, trauma, vasculitis, antiphospholipid syndrome, psoriasis, drugs.
• Beau lines and onychomadesis: severe illness, chemotherapy, hand foot and mouth disease, Kawasaki disease, drugs.
• Mees lines: arsenic and heavy metal poisoning, chemotherapy, kidney failure, severe illness.
• Muehrcke lines: hypoalbuminaemia.
• Terry nails: cirrhosis, congestive heart failure, diabetes, ageing.
• Lindsay (half and half) nails: chronic kidney disease.
• Yellow nail syndrome: lymphoedema, chronic respiratory disease and pleural effusion.
• Azure lunulae: Wilson disease, argyria.
• Red lunulae: heart failure, connective tissue disease, alopecia areata.
• Nail fold capillary abnormalities and periungual telangiectasia: systemic sclerosis, dermatomyositis, lupus.
• Leuconychia: hypoalbuminaemia, zinc deficiency, chemotherapy, trauma.
• Nail thinning and brittleness: iron deficiency, hypothyroidism, ageing, retinoids, wet work.
• Pterygium: lichen planus, scleroderma, Raynaud disease.

Drug related

• Taxane and anthracycline related onycholysis and haemorrhage.
• EGFR inhibitor paronychia and pyogenic granuloma.
• Retinoid related fragility and paronychia.
• Tetracycline photo-onycholysis and discolouration.
• Hydroxycarbamide and zidovudine melanonychia.
• Anticoagulant and antiplatelet related subungual haemorrhage.

Step 1. Triage. Look for red flags: malignancy, endocarditis, acute infection with abscess, ischaemia and trauma with fracture.

Step 2. Single digit or multiple nails, and anatomical site. A single nail points to local disease. Multiple nails point to systemic or inflammatory disease. Match the changes to the matrix, bed or fold.

Step 3. Bedside tests

• Dermoscopy of the plate and fold, and of pigmented bands (regular grey or brown lines suggest benign activation, while irregular lines, colour variation and Hutchinson sign suggest melanoma).
• Transillumination for subungual haematoma and cysts.
• Wood lamp for Pseudomonas (green fluorescence) and erythrasma.
• Capillary glucose and urinalysis.

Step 4. Microbiology

• Onychomycosis: always confirm before oral therapy. Clip the distal nail plate and scrape subungual debris, for potassium hydroxide microscopy, fungal culture, and PAS stain or PCR. False negatives are frequent, so repeat testing when suspicion is high.
• Bacterial swab and Gram stain for acute paronychia, and Pseudomonas culture for green nails.
• Viral PCR for herpetic whitlow, and swab for warts when atypical.

Step 5. Blood tests for multiple nail changes

• Full blood count, ferritin, iron studies, vitamin B12, folate.
• Urea, creatinine, eGFR, liver tests, albumin.
• Glucose or HbA1c, TSH.
• Zinc (fasting, morning) and, when drugs or exposure warrant, heavy metals (arsenic, thallium).
• HIV test, syphilis serology.
• ANA, anti dsDNA and extractable nuclear antigens when connective tissue disease is suspected, with nail fold capillaroscopy.

Step 6. Imaging and procedures

• Plain radiograph for crush injury, subungual exostosis, bone tumours and suspected osteomyelitis.
• Ultrasound or MRI for glomus tumour (MRI is the most sensitive), myxoid cyst and nail bed tumours.
• Clubbing: chest radiograph and CT chest, liver tests, faecal calprotectin when diarrhoea, oxygen saturation and echocardiography.
• Splinter haemorrhages with fever or murmur: three sets of blood cultures from separate sites before antibiotics, and transthoracic echocardiography with transoesophageal echocardiography when needed.
• Nail biopsy: lateral longitudinal biopsy, matrix punch biopsy (3 mm) or matrix shave for suspected melanoma, squamous cell carcinoma, lichen planus or unexplained matrix disease. Nail plate clipping with PAS for fungus. Send for histology by a pathologist experienced in nail pathology.
• Excisional or incisional biopsy of the entire pigmented band when melanoma is suspected. Do not shave off a pigmented band without removal of the matrix origin.

Limits. Nail psoriasis and onychomycosis coexist and look alike. Fungal culture misses a proportion of true infections. Nail biopsy can cause permanent dystrophy, so is reserved for lesions with a clear reason. Dermoscopy does not exclude nail melanoma, which may be amelanotic.

Immediate. Suspected infective endocarditis in an unwell patient: take blood cultures before antibiotics and admit.

Empiric therapy for acute native valve disease is flucloxacillin 2 g intravenously every 4 to 6 hours plus gentamicin 1 mg/kg intravenously every 12 hours. Replace flucloxacillin with vancomycin 15 to 20 mg/kg intravenously every 8 to 12 hours when MRSA is likely, in penicillin allergy or with prosthetic valves (specialist input; monitor gentamicin and vancomycin levels and kidney function).

Digital ischaemia with gangrene needs urgent vascular and rheumatology review. Acute paronychia with abscess needs drainage. Nail bed injury with fracture needs surgical repair.

General nail care. Keep nails short and clean, avoid trauma, avoid cuticle removal and artificial nails, wear cotton lined rubber gloves for wet work, and keep nail folds dry. Daily foot inspection in diabetes and arterial disease.

Onychomycosis (confirmed)

• Terbinafine 250 mg orally once daily for 6 weeks (fingernails) or 12 weeks (toenails). Check liver tests at baseline and, if treatment exceeds 6 weeks, at 6 weeks. Reduce to 125 mg daily when creatinine clearance is under 50 mL/min.
• Avoid in active liver disease and pregnancy.
• It inhibits CYP2D6 (tricyclic antidepressants, beta blockers, some SSRIs, flecainide), and rifampicin lowers its levels. Taste or smell disturbance is rare but may persist.
• Itraconazole 200 mg orally twice daily for 1 week each month, 2 pulses for fingernails or 3 pulses for toenails, or 200 mg once daily for 6 weeks (fingernails) or 12 weeks (toenails).
• Take with food. Avoid in heart failure, ventricular dysfunction, and with simvastatin, lovastatin and other contraindicated drugs. Monitor liver tests. Avoid in pregnancy.
• Fluconazole 150 to 450 mg orally once weekly (off label) until the nail has grown out: 6 months for fingernails, 9 to 12 months for toenails. Monitor liver tests and QT interval.
• Topical therapy for distal or superficial disease involving under 50% of the plate, without matrix involvement: amorolfine 5% lacquer once or twice weekly for 6 months (fingernails) to 12 months (toenails), after filing off infected nail.
• Alternatively, ciclopirox 8% lacquer daily. Topical therapy cures fewer patients than oral therapy.
• Treat tinea pedis and household contacts at the same time, change footwear, and use antifungal powder. Recurrence after treatment is common.
• Nail debridement or urea 40% paste can improve comfort in thick toenails.

Paronychia

• Acute:
  • Warm water soaks for 10 to 15 minutes, 3 to 4 times daily.
  • Flucloxacillin 500 mg orally 4 times daily for 5 to 7 days (clarithromycin 250 to 500 mg twice daily if penicillin allergic) for cellulitis.
  • Abscess: incision and drainage by lifting the nail fold, or partial nail removal, under digital block with plain lidocaine 1% (maximum 4.5 mg/kg and not over 300 mg), without adrenaline. Check tetanus immunisation.
• Chronic:
  • Avoid wet work and irritants, wear cotton lined waterproof gloves, keep nail folds dry, apply a topical corticosteroid (mometasone furoate 0.1% once daily for 3 weeks) with an azole (clotrimazole 1% or miconazole 2% twice daily for up to 3 to 6 months).
  • Oral itraconazole 200 mg once daily for 1 month may be used in refractory disease.
  • Persistent paronychia in one digit needs biopsy to exclude squamous carcinoma.
• Herpetic whitlow: aciclovir 400 mg orally 3 times daily for 7 to 10 days. Do not incise.
• EGFR inhibitor paronychia: potent topical corticosteroid, oral doxycycline 100 mg twice daily, and dose review with the oncologist.

Green nail. Remove the detached nail. Soak in 1% acetic acid twice daily, or apply a topical fluoroquinolone or gentamicin. Avoid wet work.

Nail psoriasis. Clobetasol propionate 0.05% to the nail folds and nail bed once daily for 4 to 8 weeks (maximum 50 g in any week), with calcipotriol 0.005% ointment alternating.

Intralesional triamcinolone acetonide 2.5 to 5 mg/mL, 0.1 mL into the proximal nail fold, every 4 to 6 weeks, up to 4 sessions. Tacrolimus 0.1% ointment is an alternative. Systemic therapy (methotrexate 7.5 to 25 mg weekly with folic acid 5 mg weekly on a different day, acitretin, biologic agents) for severe disease or psoriatic arthritis.

Nail lichen planus. Early treatment prevents permanent scarring and pterygium. Intralesional triamcinolone acetonide 10 mg/mL into the proximal nail fold every 4 to 6 weeks, or prednisolone 0.5 mg/kg orally daily for 3 to 6 weeks then tapering. Dermatology review.

Other causes

• Warts: salicylic acid 17 to 26% daily with paring, or cryotherapy every 2 to 3 weeks. Recurrence is frequent.
• Digital myxoid cyst: do not pierce repeatedly. Treatment is cryotherapy, sclerotherapy or surgical excision with joint debridement.
• Subungual haematoma: trephination with a sterile needle or cautery within 48 hours if painful and over 25% of the nail (evidence limited), with a radiograph if a crush injury is present. Nail bed repair for lacerations and fractures.
• Ingrown toenail: avoid cutting nails too short, wear wide footwear, and place cotton under the nail edge. Partial avulsion with chemical matricectomy for recurrent or advanced disease. Flucloxacillin 500 mg orally four times daily for 5 to 7 days for infection.
• Koilonychia from iron deficiency: ferrous sulphate 200 mg (65 mg elemental iron) orally once daily or on alternate days, continued for 3 months after haemoglobin normalises, with investigation of the cause.
• Clubbing, Beau lines, Terry nails, Lindsay nails, Muehrcke lines and yellow nail syndrome: treat the cause. Evidence for treatment of yellow nail syndrome itself is limited.
• Melanoma or squamous cell carcinoma: urgent oncological care, wide excision or amputation at the distal interphalangeal joint, and staging as directed by the specialist.
• Benign activation melanonychia (multiple bands in dark skin) needs observation with photographs.
• Glomus tumour: surgical excision.
• Drug related: review the drug with the prescriber and avoid unnecessary changes in cancer therapy. Frozen glove or cold therapy may reduce taxane related nail toxicity (evidence limited).

Monitoring. Review at 4 to 6 weeks for infection, at 3 months for antifungal response (nail growth takes 6 to 18 months to confirm clearing), and every 3 months for pigmented bands and chronic disease. Keep a photographic record.

Referral and escalation. Dermatology within 2 weeks for suspected nail melanoma, squamous cell carcinoma, lichen planus, or persistent single nail dystrophy. Hand surgery for deep infection, flexor tenosynovitis, glomus tumour and nail bed injury. Podiatry for diabetic and vascular nail care. Cardiology and infectious diseases for suspected endocarditis. Respiratory medicine and oncology for new clubbing. Rheumatology for connective tissue disease and vasculitis.

Admission criteria. Suspected endocarditis, tenosynovitis, necrotic or ischaemic digits, severe infection, and open fractures of the distal phalanx.

Disposition. Most patients are managed in primary care. Safety net advice: return for rapid change of a pigmented streak, a bleeding or ulcerated nail, throbbing pain with redness spreading up the finger, fever, new breathlessness or cough, or pale, blue or black fingers or toes.