Nail disorders

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Common Nail Disorders

Onychomycosis (tinea unguium)

• Fungal infection of the nail plate and/or nail bed; commonest nail disorder.^[2][4]
• Clinical: thickened, discoloured (yellow-brown-white), crumbling nail plate; subungual hyperkeratosis; onycholysis.^[4]
• Usually toenails (often asymmetric); may spread from tinea pedis.
• Organisms: dermatophytes (Trichophyton rubrum the most common; ~90% of toenail and ~75% of fingernail infections), Candida, non-dermatophyte moulds (Scopulariopsis, Aspergillus).^[4][5]
• Diagnosis: CONFIRM with fungal culture/PCR BEFORE starting oral antifungals (laboratory confirmation should be considered before treatment; clinical appearance alone is unreliable). Send nail clippings for: (1) KOH microscopy (immediate; lower sensitivity); (2) fungal culture (identifies the organism; false-negative rates are high — repeat sampling if negative); (3) PCR (improved detection rates for dermatophytes compared with culture).^[2][4]
• Treatment:^[2]
  • Oral terbinafine 250 mg daily — first-line for dermatophyte onychomycosis; 6 weeks (fingernails), 12 weeks (toenails); monitor LFTs (oral antifungals carry hepatotoxicity).^[2][23]
  • Oral itraconazole pulse therapy (200 mg twice daily for 1 week, then 3 weeks off) — alternative agent; effective for dermatophyte toenail disease.^[23]
  • Topical (amorolfine lacquer weekly, ciclopirox lacquer daily) — for mild/localised disease or as adjunct; lower cure rates than oral therapy with much longer regimens.^[4]
  • Prevent recurrence: treat concurrent tinea pedis; sanitize shoes and socks; avoid walking barefoot in public places.^[4]
• Nail grows slowly: approximately 2-3 mm/month with complete replacement in 6-9 months → visible improvement takes months; toenails take the longest.^[22]

Nail psoriasis

• Pitting (ice-pick depressions on the nail plate surface), oil-drop/salmon patches (yellow-brown discoloration under the nail), onycholysis (separation of nail plate from bed; usually with an erythematous border), subungual hyperkeratosis (thickening under the nail).^[1]
• Management: treat underlying psoriasis; topical calcipotriol (vitamin D analogue) under the nail; intralesional triamcinolone into nail matrix; systemic/biologic for severe disease.^[1]

Nail lichen planus

• Thinning, longitudinal ridging, fissuring of the nail plate; dorsal pterygium (the nail fold fuses with the nail bed → permanent scarring and nail loss).^[3]
• May affect one or several nails; permanent nail loss if untreated.
• Management: urgent treatment to prevent permanent scarring (pterygium is irreversible); potent topical or intralesional corticosteroids; systemic corticosteroids for severe/progressive disease.^[3]

Other common nail disorders

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Special Nail Disorders & Morphology^[1]

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Rarer Nail Signs & Syndromes — High-Yield for Fellowship Viva

This section covers the less common but classically tested nail signs that examiners love. Each has a specific systemic association — knowing the morphology is half the answer; knowing the underlying cause is the other half.^[1]

Koilonychia (spoon nails)

Concave, spoon-shaped depression of the nail plate that can hold a drop of water. Typically affects the fingernails; toenail involvement is common in young children. Iron store abnormalities, including iron deficiency anaemia, are the classic associations, and koilonychia is also seen in Plummer-Vinson syndrome, other nutritional deficiencies, inflammatory dermatoses such as psoriasis and lichen planus, onychomycosis, and occupational or traumatic causes. In young children, toenail koilonychia is commonly transient and idiopathic. Workup: follow the published evaluation algorithm — history, examination for cutaneous and systemic associations, and iron studies where indicated. Treat the cause — the nails regrow with replacement of iron.^[5]

Anonychia and onychatrophy

Anonychia = complete absence of the nail plate from birth (congenital) or following destruction of the matrix. Congenital anonychia is rare and may be isolated (autosomal dominant or recessive) or part of syndromes such as nail–patella syndrome (Fong disease) with absent/hypoplastic patellae, iliac horns, elbow dysplasia, and Lunula triangularis (triangular lunulae — pathognomonic). Acquired anonychia follows scarring lichen planus, severe trauma, burns, or Stevens-Johnson syndrome. Onychatrophy describes a shrunken, atrophic, rudimentary nail that fails to grow — also seen in lichen planus, peripheral vascular disease, and epidermolysis bullosa.^[1]

Pterygium (dorsal and ventral)

Dorsal pterygium (nail lichen planus): the proximal nail fold fuses with the nail bed, splitting the nail into two portions that gradually shrink; the central split resembles a pterygium (wing). Irreversible scarring — every attempt at treatment is to halt progression, not regrow nail. Urgent potent/intralesional corticosteroid is the cornerstone. Ventral pterygium is rarer and may occur in Raynaud's disease, scleroderma, and graft-versus-host disease. Pseudo-pterygium is post-traumatic adhesion without active disease.^[1]

Digital clubbing

Bulbous enlargement of the distal phalanx with loss of the Lovibond angle (normal less than 180°; clubbing greater than 180°). Schamroth's window test — placing the dorsal surfaces of two opposite distal phalanges together normally produces a diamond-shaped gap; in clubbing the gap obliterates. Phalangeal depth ratio (distal phalangeal depth / interphalangeal joint depth greater than 1) is the bedside screening rule. Causes: bronchogenic carcinoma (especially non-small-cell, apical; look for Horner's), suppurative lung disease (bronchiectasis, empyema, lung abscess, cystic fibrosis), cyanotic congenital heart disease, infective endocarditis, IBD (especially Crohn's), cirrhosis, thyroid acropachy, and idiopathic / familial. Unilateral clubbing suggests subclavian artery aneurysm, Pancoast tumour, or brachial plexus lesion. Rapid-onset clubbing + joint pain = hypertrophic pulmonary osteoarthropathy (synovitis, periostitis, finger clubbing) — think lung cancer.^[1]

Lindsay's nails (half-and-half nails)

First described by Lindsay in 1967 in chronic renal failure. The nail plate shows a distinct sharp demarcation: the proximal half is white / dull (ground-glass appearance) and the distal half is red, pink, or brown. The border does NOT move with nail growth (unlike Mees lines) — suggesting nail bed rather than nail plate pathology. Half-and-half nails are a common manifestation of end-stage renal disease and dialysis, alongside pruritus, xerosis, and hyperpigmentation, and may resolve with dialysis or improvement of renal function. Not pathognomonic — also reported in healthy individuals.^[9]

Splinter haemorrhages

Tiny linear, reddish-brown, longitudinally oriented streaks under the nail plate, resembling wood splinters under the nail. They represent microemboli or microthrombi in the longitudinally oriented capillaries of the nail bed. The classic association is infective endocarditis — but trauma is the commonest cause (most distal splinters; usually 1-2 nails). Proximal splinters or multiple splinters across many nails raise concern for SBE, antiphospholipid syndrome, vasculitis (polyarteritis nodosa, microscopic polyangiitis, rheumatoid vasculitis), cryoglobulinaemia, scurvy, and psoriasis. On exam: count the splinters, check the distribution (distal vs proximal, single vs multiple), look for other stigmata (Janeway lesions, Osler nodes, Roth spots, murmur), and order blood cultures × 3, echo, ANA, ANCA, antiphospholipid antibodies, and viral hepatitis serology as clinically indicated.^[1]

Muehrcke's lines

Paired, transverse, white bands that run parallel to the lunula across multiple nails — first described by Robert Muehrcke in 1956 in a cohort of 65 patients. Unlike Mees or Beau lines, Muehrcke's lines do NOT move with nail growth (they are in the nail bed, not the nail plate — an apparent leukonychia) and fade with pressure while the nail stays transparent. Classically associated with hypoalbuminaemia; seen in nephrotic syndrome, liver disease, severe malnutrition, chemotherapy, and other systemic conditions. They resolve as albumin normalises. Differentiate from Mees lines (transverse white lines that MOVE with nail growth; arsenic/thallium/heavy-metal poisoning, chemotherapy).^[11][10]

Terry's nails

Originally described by Dr. Richard Terry in 1954 in patients with hepatic cirrhosis. The nail shows ground-glass opacification of nearly the entire nail with obliteration of the lunula and a narrow band of normal, pink nail bed at the distal border. Like Muehrcke's, it does not move with growth — it is an apparent leukonychia of the nail bed. Causes: cirrhosis — prospectively, 25.6% of cirrhotics have Terry nails, with cirrhosis the only significant correlate (OR 5.7) — plus chronic congestive heart failure, chronic renal failure, diabetes mellitus type 2, and normal aging. Pathophysiology involves nail-bed vascularity change secondary to connective-tissue overgrowth, with telangiectasias in the distal band. Distinguish from Lindsay (half-and-half) — Terry has a narrower distal pink band — and from true leukonychia totalis/partialis.^[7][8]

Half-and-half nails (Lindsay) vs Terry's vs Muehrcke's vs Mees

All four are white abnormalities of the nail and commonly confused. The key discriminators:^[10]

• Lindsay / half-and-half — proximal half white, distal half red-brown/pink with sharp border; does NOT move with growth; end-stage renal disease / dialysis; nail-bed sign.^[9]
• Terry's — ground-glass white nail with narrow distal pink band, lunula obliterated; does NOT move; cirrhosis, CHF, chronic renal failure, aging; apparent leukonychia.^[7]
• Muehrcke's — paired transverse white lines parallel to the lunula that do NOT move with growth; fade with pressure; hypoalbuminaemia (nephrotic syndrome, liver disease, malnutrition).^[11]
• Mees — single transverse white line(s) that DO move with growth; no blanching; arsenic / thallium poisoning, chemotherapy, heavy metals — nail plate sign.^[25][10]

Yellow nail syndrome (YNS)

A rare syndrome characterised by a clinical triad of xanthonychia (thickened, slow-growing, yellow nails with growth arrest and increased transverse curvature), lymphoedema, and respiratory disease — most often pleural effusion and bronchiectasis, with chronic rhinosinusitis less common. Manifestations often do not occur concurrently, making diagnosis challenging; pathogenesis remains obscure (lymphatic dysfunction proposed). In an international cohort of 111 patients, xanthonychia with growth arrest plus respiratory disease or lymphoedema was highly suggestive, and oral vitamin E combined with oral azole antifungals achieved the highest complete-response rate; high-dose vitamin E has the longer record as monotherapy. Associations include malignancy, immunodeficiency, and connective tissue disease. Differential includes onychomycosis (KOH positive) and psoriatic onycholysis.^[12][13]

^{[12] [13] [14] [9] [1] [10] [12]}

Procedures & Surgical Management

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Nail matrix biopsy — operative technique and indications

When a pigmented or unexplained nail lesion must be sampled, the site of biopsy determines what pathology you can diagnose, and the technique differs from cutaneous punch biopsy. For a longitudinal melanonychia (single pigmented band, especially with Hutchinson's sign), the standard is a 3 mm punch biopsy of the proximal nail fold and matrix centred over the pigment origin, or a longitudinal lateral biopsy of the entire matrix if the band is wide or atypical — the latter gives full-thickness histology and is the preferred approach in most centres for suspected subungual melanoma because it allows accurate Breslow depth measurement, which shave biopsy cannot.^[1]

Steps: (1) digital nerve block with 1-2% plain lidocaine (no adrenaline); (2) exsanguinate and apply a digital tourniquet (Penrose drain or commercial finger tourniquet — record time, maximum 30 min); (3) avulse the overlying nail plate by splitting longitudinally with a Beaver blade and lifting it off the matrix; (4) for matrix biopsy, take a 3 mm punch through the matrix to bone (matrix lies just above bone, full-thickness is required for staging); (5) for bed biopsy, take a 2-3 mm wide × 4-5 mm long ellipse from the bed after avulsion; (6) suture the matrix defect with absorbable 6-0 if needed; (7) dress and remove tourniquet. Onychocryptosis (matrixectomy with phenol 88%) is technically a destruction not a biopsy — the avulsed lateral spicule is sent only if clinically suspicious, but the procedure is therapeutic, not diagnostic. Send all true biopsies in formalin for histopathology; do NOT put phenol-treated tissue in formalin for histology as it is destroyed.^[1]

Specific drug doses — onychomycosis oral regimens

Three oral regimens are the workhorses; choose on organism, comorbidity and drug interactions. Baseline LFTs are mandatory for all three; recheck at 4-6 weeks if abnormal or on long courses.^[2][4]

• Terbinafine 250 mg once daily — first-line for dermatophyte onychomycosis (Trichophyton rubrum, T. mentagrophytes); 6 weeks for fingernails, 12 weeks for toenails; check baseline LFTs (oral antifungals carry hepatotoxicity and drug-interaction risks).^[2][23]
• Itraconazole 200 mg pulse — 200 mg twice daily for 1 week, then 3 weeks off (three pulses over 12 weeks treats toenail disease); alternative for dermatophytes, also covers Candida and some non-dermatophyte moulds.^[23]
• Fluconazole 150 mg once weekly — third-line option when terbinafine and itraconazole are contraindicated or poorly tolerated.^[2]

Topical adjuncts (mild disease, superficial white onychomycosis, or adjuvant to oral): amorolfine lacquer once weekly, ciclopirox lacquer daily. Systemic nail treatment is slow because the nail grows approximately 2-3 mm/month and complete replacement takes 6-9 months — clinical cure of toenails takes longer.^[22][4]

^{[16] [17] [15] [23]}

Onychomycosis vs Nail Psoriasis vs Nail Lichen Planus

^{[1] [1] [1] [1] [18] [19]}

Nail Signs of Systemic Disease

Onychomycosis Diagnosis and Management

• ALWAYS confirm with fungal culture/PCR before starting oral antifungal — laboratory confirmation should be considered before treatment; clinical appearance alone is unreliable, and oral antifungals carry hepatotoxicity, drug interactions, and cost.^[2][4]
• Terbinafine = treatment of choice for dermatophyte onychomycosis (T. rubrum and T. mentagrophytes the leading dermatophytes); fungicidal.^[2][5]
• Itraconazole = alternative; broader spectrum (also covers Candida and some moulds); pulse regimen 200 mg twice daily for 1 week per month.^[23]
• Nail grows slowly (about 2-3 mm/month) → visible improvement takes months; complete replacement in 6-9 months, longest for toenails.^[22]

Exam Pearls

Red Flags

Exam application bank (NEET-PG / INICET)

One-line answer

Comprehensive nail disorders reference for MBBS/board exam: Onychomycosis (tinea unguium — confirm with KOH/PCR before oral antifungal; terbinafine 250 mg daily 6wk finger/12wk toe first-line; alternatives itraconazole pulse 200 mg BID 1-week-on/3-weeks-off ×3, fluconazole 150 mg weekly); Nail psoriasis (pitting, oil-drop, onycholysis with erythematous border); Nail lichen planus (dorsal pterygium is irreversible scarring — urgent corticosteroid); Beau's lines, Onycholysis, Koilonychia (iron deficiency), Melanonychia (single band + Hutchinson's sign → subungual melanoma biopsy). Special types: trachyonychia / twenty-nail dystrophy (rough nails ± alopecia areata; biotin 5-10 mg daily for brittle nails, biotin deficiency dose 5 mg), median nail dystrophy (central canaliform split), onychogryphosis (ram's horn toenail), onychauxis (thickened nail without deformity), parakeratosis pustulosa^[1]

Worked stems (answer without another resource)

Stem 1 — Classic presentation. Map symptoms to mechanism; name the first investigation and first treatment step with dose/route if drug therapy is standard.^[5][6]

Stem 2 — Unstable / complicated. List red flags that force immediate resuscitation, theatre, ICU, antidote, or reperfusion — and what you do in the first 15 minutes.^[1]

Stem 3 — Atypical group. Elderly, pregnancy, child, or immunocompromised: how presentation and thresholds change.^[1]

Stem 4 — Differential trap. Name the three closest mimics and one discriminator for each.^[1]

Stem 5 — Disposition. Who goes home with safety-netting, who is admitted, who needs HDU/ICU/theatre, and what follow-up is mandatory.^[1]

Rapid viva checklist

1. Definition + classification
2. Pathophysiology chain
3. Bedside signs / criteria
4. Score with exact components (if any)
5. Emergency bundle
6. Definitive therapy with doses
7. Complications of disease and of treatment
8. Special populations
9. Guideline/trial name if classic
10. Three exam traps

Coverage self-check

If you cannot answer any stem above from this page alone, re-read the matching section — the page is intended to be self-sufficient for final-prof and NEET-PG/INICET questions on Nail disorders.

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References22ShowHide

1. [1]Hwang JK, Grover C, Iorizzo M, et al. Nail psoriasis and nail lichen planus: Updates on diagnosis and management. Journal of the American Academy of Dermatology, 2024.PMID 38007038
2. [2]Lipner SR, Scher RK. Onychomycosis: Treatment and prevention of recurrence. Journal of the American Academy of Dermatology, 2019.PMID 29959962
3. [3]Gupta MK, Lipner SR. Review of Nail Lichen Planus: Epidemiology, Pathogenesis, Diagnosis, and Treatment. Dermatologic Clinics, 2021.PMID 33745635
4. [4]Gupta AK, Stec N, Summerbell RC, et al. Onychomycosis: a review. Journal of the European Academy of Dermatology and Venereology : JEADV, 2020.PMID 32239567
5. [5]Leung AKC, Lam JM, Leong KF, et al. Onychomycosis: An Updated Review. Recent patents on inflammation & allergy drug discovery, 2020.PMID 31738146
6. [6]Tully AS, Trayes KP, Studdiford JS. Evaluation of nail abnormalities. American Family Physician, 2012.PMID 22534387
7. [7]Witkowska AB, Jasterzbski TJ, Schwartz RA. Terry's Nails: A Sign of Systemic Disease. Indian Journal of Dermatology, 2017.PMID 28584375
8. [8]Sack JS, Liu AF, Gray M, Roat J, Zucker SD. Association of Terry Nails With Liver Cirrhosis. American Journal of Gastroenterology, 2021.PMID 34459471
9. [9]Markova A, Lester J, Wang J, Robinson-Bostom L. Diagnosis of common dermopathies in dialysis patients: a review and update. Seminars in Dialysis, 2012.PMID 22809004
10. [10]Iorizzo M, Starace M, Pasch MC. Leukonychia: What Can White Nails Tell Us? American Journal of Clinical Dermatology, 2022.PMID 35112320
11. [11]Ramachandran V, Sapra A. Muehrcke Lines of the Fingernails. 2026.PMID 32644562
12. [12]Curtis KL, Piraccini BM, Starace M, et al. Diagnosis and management of yellow nail syndrome: An international multi-institutional retrospective cohort study of 111 cases by an expert panel. Journal of the American Academy of Dermatology, 2025.PMID 40692045
13. [13]Tosti A, Piraccini BM, Iorizzo M. Systemic itraconazole in the yellow nail syndrome. British Journal of Dermatology, 2002.PMID 12072079
14. [14]Hoover-Fong JE, McIntosh I. Nail-Patella Syndrome. 1993.PMID 20301311
15. [15]Shajil C, Kumari R. Surgical Matricectomy Versus Phenolization in the Treatment of Ingrown Toenails: A Randomized Controlled Trial. Dermatologic Surgery, 2023.PMID 36735804
16. [16]Muriel-Sánchez JM, Coheña-Jiménez M, Montaño-Jiménez P. Effect of Phenol Application Time in the Treatment of Onychocryptosis: A Randomized Double-Blind Clinical Trial. International Journal of Environmental Research and Public Health, 2021.PMID 34639778
17. [17]Córdoba-Fernández A, Rodríguez-Delgado FJ. Anaesthetic digital block with epinephrine vs. tourniquet in ingrown toenail surgery: a clinical trial on efficacy. Journal of the European Academy of Dermatology and Venereology, 2015.PMID 25284453
18. [18]Relhan V, Bansal A. Acute and Chronic Paronychia Revisited: A Narrative Review. Journal of Cutaneous and Aesthetic Surgery, 2022.PMID 35655642
19. [19]Iorizzo M, Pasch MC. Bacterial and viral infections of the nail unit: Tips for diagnosis and management. Hand Surgery and Rehabilitation, 2024.PMID 36427761
20. [22]Gupta AK, Gover MD, Lynde CW. Pulse itraconazole vs. continuous terbinafine for the treatment of dermatophyte toenail onychomycosis in patients with diabetes mellitus. Journal of the European Academy of Dermatology and Venereology, 2006.PMID 17062029
21. [23]Tausch I, Bräutigam M, Weidinger G, Mensing H. Evaluation of 6 weeks treatment of terbinafine in tinea unguium in a double-blind study. British Journal of Dermatology, 1997.PMID 9205509
22. [25]Mirfazaelian H, Daneshkhah K. Mees' lines. TheScientificWorldJournal, 2011.PMID 21298217