Lichen Planus Nail: Toenail and Fingernail Changes, Diagnosis, and Treatment

Nail lichen planus (nail LP) is an inflammatory dermatosis affecting the nail unit — the nail matrix, nail bed, nail folds, and hyponychium — producing a characteristic spectrum of nail changes that range from longitudinal ridging and thinning to total nail destruction (twenty-nail dystrophy). It accounts for approximately 10% of all lichen planus cases and is clinically important because nail involvement can occur in isolation without skin or mucosal lichen planus, and because severe matrix involvement produces irreversible nail loss (pterygium unguis) if not treated early. Toenails are involved less commonly than fingernails, but toenail involvement presents with the same spectrum of changes and the same risk of permanent nail destruction.

Nail Lichen Planus: Clinical Features and Differential Diagnosis

Feature	Nail Lichen Planus	Onychomycosis (Nail Fungus)	Psoriatic Nails	Trachyonychia (Twenty-Nail Dystrophy)
Nail plate appearance	Longitudinal ridging (striae); thinning; splitting; friable brittle nail; may progress to total nail destruction	Subungual hyperkeratosis; yellow-brown-white discoloration; nail thickening; onycholysis; debris under nail	Pitting (small ice-pick pits); onycholysis; oil-drop sign (salmon patch); subungual hyperkeratosis; nail thickening	Diffuse longitudinal ridging and sandpaper-like roughness of all 20 nails; nail plate thinning; no subungual debris
Pathognomonic finding	Pterygium unguis — forward extension of proximal nail fold over nail plate, obliterating the nail — indicates matrix scarring; IRREVERSIBLE once established	Positive KOH or culture; dermatophytoma streak; proximal subungual pattern suggests immunocompromise	Geometric pitting (multiple, regular); oil-drop discoloration; psoriatic plaques on skin; arthritis	All nails affected (20); no pitting or oil-drop sign; no subungual debris; nail plate thin and ridged
Nail matrix involvement	Primary pathology — inflammation and scarring of matrix produces all nail plate changes; matrix biopsy diagnostic	Usually absent — fungi primarily in nail bed and plate; matrix involvement in proximal subungual type only	Nail matrix inflammation produces pitting; nail bed inflammation produces oil-drop sign and onycholysis	Matrix inflammation (idiopathic or LP-related); all 20 nails ridged from diffuse matrix involvement
Associated features	Cutaneous LP (flat-topped violaceous papules on wrists, ankles); oral LP (white Wickham striae on buccal mucosa); 10-15% nail LP without skin lesions	Adjacent tinea pedis; immunocompromise; diabetic neuropathy; nail trauma history	Psoriatic plaques on skin; scalp psoriasis; psoriatic arthritis; positive family history	LP (most common association); alopecia areata; atopic dermatitis; idiopathic; usually children or young adults
Reversibility	Reversible if treated before pterygium forms; IRREVERSIBLE once pterygium unguis established (scar tissue in matrix)	Reversible with antifungal treatment; recurrence common; cure rates 50-70% with oral terbinafine	Nail psoriasis improves with systemic treatment; biologics most effective	Often spontaneously improves in children; adults more persistent; LP-associated cases improve with LP treatment

Nail Lichen Planus: Severity Staging and Treatment Protocol

Severity	Clinical Features	Treatment Options	Expected Outcome
Mild (1-5 nails; no pterygium)	Longitudinal ridging; mild thinning; splitting of 1-5 nails; no proximal nail fold adherence	Topical corticosteroid (clobetasol 0.05% under occlusion nightly); topical tacrolimus 0.1%; nail lacquers with urea for brittleness; patient education on pterygium risk	50-70% stabilization and partial improvement with topical therapy; close monitoring for pterygium development
Moderate (5+ nails; at-risk for pterygium)	Multiple nail involvement; thinning and fragility; early proximal nail fold adherence; approaching pterygium formation	Intralesional triamcinolone acetonide (2.5-5 mg/mL) injected at proximal nail fold quarterly; systemic corticosteroid short course (prednisone 0.5 mg/kg/day x 4-6 weeks); topical as adjunct	Intralesional steroids most effective for matrix sparing; 60-80% halt of progression; new nail growth requires 6-12 months to assess
Severe (pterygium forming; major nail loss)	Pterygium unguis present; significant nail plate loss; 10+ nails involved; severe ridging and thinning	Systemic immunosuppression: prednisone + methotrexate; hydroxychloroquine; acitretin (retinoid); cyclosporine; case reports of JAK inhibitors (tofacitinib)	Cannot reverse established pterygium — treatment arrests further destruction; partial regrowth of remaining nail possible; 40-60% meaningful response to systemic therapy
Total nail destruction	All nails destroyed; pterygium all nails; no nail plate present; nail folds scarred	Systemic immunosuppression for any remaining intact nails; accept cosmetic prosthetic nails for destroyed nails; pain management	Cannot restore destroyed nails; systemic therapy prevents further nail loss in remaining nails; prognosis poor for full recovery

At Balance Foot & Ankle in Howell and Bloomfield Hills, toenail lichen planus is distinguished from onychomycosis by the absence of subungual debris, the longitudinal ridging pattern, and the presence of pterygium unguis — biopsy is obtained from the proximal nail fold when clinical diagnosis is uncertain, and dermatology co-management is initiated early for any patient with multiple nail involvement because pterygium formation is irreversible. Call (810) 206-1402.