What does a transverse white line in the nail indicate?

Transverse White Lines in the Nail

A transverse white line in the nail most commonly indicates either leukonychia striata (Muehrcke's lines) from systemic illness, medication, or metabolic disturbance, or represents transverse furrowing from Candida paronychia if associated with nail fold inflammation.

Primary Differential Diagnosis

Fungal Infection (Candida Paronychia)

• Transverse furrowing or pitting occurs in Candida paronychia when infection and inflammation affect the nail matrix, causing secondary nail dystrophy 1
• This pattern typically affects fingernails more than toenails, particularly in individuals with occupational water immersion 1
• The nail becomes more opaque with white, green, or black marks appearing in proximal and lateral portions, accompanied by periungual swelling and erythema 1
• Key distinguishing feature: pressure on and movement of the nail is painful, unlike dermatophyte infections 1

Leukonychia Striata (Muehrcke's Lines)

• Transverse white bands represent vascular nail bed abnormalities associated with systemic illness, medications (including chemotherapy and transretinoic acid), or acute infections 2, 3
• These are apparent leukonychias (affecting the nail bed, not the nail plate itself), which blanch with pressure 4
• Common triggers include acute systemic infections (tuberculosis, empyema), metabolic disturbances, and drug exposures 3

Beau's Lines Spectrum

• Transverse grooves or depressions from temporary nail matrix arrest, which can progress to onychomadesis (nail shedding) in severe cases 5
• Width of the line correlates with duration of the causative insult 5
• Associated with fever, severe infection, vasculitis, major medical illness, or chemotherapy 5

Diagnostic Approach

Examine for associated findings to differentiate causes:

• Check for periungual inflammation: Swollen, erythematous nail folds with pain on nail pressure suggest Candida paronychia 1
• Assess occupational history: Repeated water immersion points toward Candida infection 1
• Evaluate for systemic illness: Recent acute infection, metabolic disturbance, or medication exposure suggests leukonychia striata 2, 3
• Test blanching: Press on the white line—if it blanches, this indicates vascular nail bed pathology (apparent leukonychia) rather than nail plate abnormality 4

Laboratory Confirmation for Fungal Etiology

• Obtain nail specimens from discolored or dystrophic areas for KOH preparation and fungal culture 6
• Critical pitfall: Do not diagnose fungal infection based on appearance alone, as 50% of nail dystrophy cases are non-fungal 7

Management Based on Etiology

If Candida Paronychia Confirmed

• Topical antifungals are NOT recommended for transverse or striate infections 1
• Systemic azole therapy is indicated when Candida species are confirmed 7
• Address underlying predisposing factors (water exposure, occupational modifications) 1

If Leukonychia Striata (Systemic/Drug-Related)

• This is a self-limited condition requiring no specific treatment 2
• Reassure the patient and avoid unnecessary diagnostic workup 2
• The white bands will grow out with the nail over several months
• Address the underlying systemic condition or discontinue offending medication if identified 2, 3

If Beau's Lines/Nail Matrix Arrest

• No specific treatment required; nail changes resolve spontaneously as the nail grows out (typically 4 months for complete recovery) 5
• Monitor for progression to onychomadesis if the insult was severe 5

Key Clinical Pitfalls

• Do not assume fungal infection without laboratory confirmation, as multiple non-infectious causes produce similar appearance 7
• Do not use topical antifungals for transverse white lines in suspected fungal infection, as these forms require systemic therapy 1
• Do not pursue extensive workup for drug-induced leukonychia striata, as the condition is benign and self-resolving 2