Lichen Planopilaris

Lichen planopilaris (LPP) is a chronic inflammatory condition that causes permanent, scarring hair loss (cicatricial alopecia). It is the follicular form of lichen planus — a condition in which the immune system attacks the hair follicles, destroying them and replacing them with scar tissue. Once a follicle is destroyed, the hair in that area cannot regrow.

LPP predominantly affects middle-aged women, though it can occur in men and at any age.

• Prevalence: LPP is uncommon but accounts for approximately 43% of all primary scarring alopecia cases
• Age: Most commonly diagnosed between ages 40 and 60
• Gender: Women are affected approximately 5 times more often than men
• Ethnicity: Occurs in all ethnic groups; no clear ethnic predisposition

LPP typically presents with patches of hair loss on the scalp that progressively expand.

• Perifollicular erythema: Redness surrounding individual hair follicles at the edges of bald patches
• Follicular hyperkeratosis: Small, rough scales forming plugs around hair shafts (peripilar casts)
• Scalp symptoms: Itching, burning, pain, or tenderness of the affected areas (trichodynia)
• Scarring: Smooth, shiny, pale areas where hair follicles have been permanently destroyed — follicular openings are absent
• Pull test: Hair at the margins of active patches is easily pulled out

Three clinical subtypes are recognized:

• Classic LPP: Scattered patches of scarring hair loss, mainly on the vertex and parietal scalp
• Frontal fibrosing alopecia (FFA): Progressive, symmetrical recession of the frontotemporal hairline, often with eyebrow loss; most common in postmenopausal women
• Graham-Little-Piccardi-Lassueur syndrome: A rare triad of cicatricial scalp alopecia, non-scarring hair loss of the axillae and groin, and follicular keratotic papules on the trunk

LPP is an autoimmune condition in which cytotoxic T-lymphocytes (a type of immune cell) attack the stem cells of the hair follicle, located in a region called the bulge.

• Immune privilege collapse: The hair follicle normally shields its stem cells from immune attack; in LPP, this protection breaks down, allowing immune cells to infiltrate and destroy the follicle
• Inflammatory cascade: Interferon-gamma drives inflammation around the follicle, leading to fibrosis (scarring) and permanent follicle loss
• Potential triggers: Certain medications (checkpoint inhibitors, beta-blockers), viral infections (hepatitis C), and hormonal changes have been implicated, though in most cases no specific trigger is identified
• Genetic predisposition: A familial tendency has been observed, but specific genetic markers have not been definitively identified

Diagnosis relies on a combination of clinical examination, trichoscopy, and histopathology.

• Clinical examination: Patches of scarring alopecia with perifollicular erythema and follicular keratosis at the borders; positive pull test at active margins
• Trichoscopy (dermoscopy of the scalp): Reveals peripilar casts (cylindrical scales around hair shafts), perifollicular erythema, blue-grey dots, loss of follicular openings in scarred areas, and tufted follicles
• Scalp biopsy: Shows a band-like lymphocytic infiltrate at the level of the infundibulum and isthmus, interface dermatitis of the outer root sheath, and perifollicular fibrosis (lamellar fibrosis around the follicle)
• Direct immunofluorescence: Colloid bodies (IgM) at the basement membrane zone; helps differentiate from discoid lupus erythematosus
• Lichen Planopilaris Activity Index (LPPAI): A validated scoring tool used to track disease activity based on symptoms, signs, and pull test results

There is no cure for LPP. Treatment aims to halt disease progression, reduce symptoms, and preserve remaining hair follicles. Hair that has already been permanently lost cannot be restored.

For mild or localized disease:

• High-potency topical corticosteroids (clobetasol propionate 0.05%) applied to active areas
• Intralesional corticosteroid injections (triamcinolone acetonide 5–10 mg/mL) every 4–6 weeks
• Topical calcineurin inhibitors (tacrolimus 0.1%) as a steroid-sparing alternative

For moderate to severe or progressive disease:

• Hydroxychloroquine 200 mg twice daily — the most commonly used systemic agent for LPP
• Methotrexate 15 mg/week — considered when hydroxychloroquine is insufficient
• Doxycycline 100 mg twice daily — for its anti-inflammatory properties
• Pioglitazone 15–30 mg daily — targets a specific molecular defect (PPAR-gamma deficiency) observed in LPP

Adjunctive measures:

• Topical minoxidil to support remaining follicles
• Avoidance of physical or chemical hair damage (tight hairstyles, excessive heat, chemical treatments)
• Psychological support — hair loss can significantly affect self-esteem and quality of life

Prognosis: LPP follows a chronic, relapsing course. Early treatment is essential, as hair loss in scarred areas is permanent. With appropriate therapy, disease progression can often be slowed or halted, but sustained treatment is typically required — discontinuation is associated with a relapse rate of approximately 30%.

• LPP causes permanent hair loss in affected areas — early treatment helps preserve remaining hair
• The condition is not contagious and is not caused by anything you did
• Treatment can control the disease but does not cure it; long-term therapy is often necessary
• When to seek medical attention: Progressive hair loss with scalp itching, burning, or tenderness; visible scarring or smooth hairless patches; eyebrow thinning or loss of body hair
• Regular dermatological follow-up is important to monitor disease activity and adjust treatment
• Up to 50% of patients with LPP may also develop lichen planus affecting the skin, mouth, or nails

• Prevalence: LPP accounts for approximately 43% of primary scarring alopecias (Lepe et al., 2024). Among cicatricial alopecias evaluated in specialized clinics, LPP and its variants are the most common lymphocytic forms.
• Demographics: Female predominance with F:M ratio of approximately 4.9:1 for classic LPP and up to 31:1 for FFA (Meinhard et al., 2014). Mean age at diagnosis is approximately 55 years (Brankov et al., 2018).
• Comorbidities: Hypothyroidism (24.3%), Hashimoto's thyroiditis (6.3%), hirsutism (11.4%) are significantly more prevalent in LPP patients compared to controls. Association with autoimmune conditions including vitiligo, rheumatoid arthritis, and celiac disease has been reported.
• Trends: The incidence of FFA has risen sharply since its first description in 1994, suggesting either a true increase or improved recognition. Environmental factors, including certain sunscreen ingredients and leave-on cosmetics, have been hypothesized as potential triggers for FFA.

Immune Privilege Collapse

The central pathogenic event in LPP is the collapse of immune privilege (IP) at the hair follicle bulge, the anatomical niche housing epithelial hair follicle stem cells (eHFSCs). Under normal conditions, the bulge maintains IP through downregulation of MHC class I/II molecules and expression of immunosuppressive factors (TGF-β2, CD200, IDO).

In LPP, this IP collapses:

• Upregulation of MHC class I, MHC class II, and β2-microglobulin in lesional follicles
• Decreased expression of IP guardians TGF-β2 and CD200
• IFN-γ is the principal cytokine driving IP collapse (Harries et al., 2013)

T-Cell Mediated Follicular Destruction

• CD8+ cytotoxic T lymphocytes and CD123+ plasmacytoid dendritic cells accumulate around the isthmus and infundibulum
• Th1-biased immune response with elevated CXCR3 expression and IFN-γ-inducible chemokines (CXCL9, CXCL10, CXCL11)
• The IFN-γ/CXCL10 axis sustains chronic inflammation and recruits additional effector cells
• JAK-STAT pathway activation mediates IFN-γ signaling — providing rationale for JAK inhibitor therapy

Stem Cell Destruction and Fibrosis

• Lesional eHFSCs show increased apoptosis and loss of stem cell molecular signatures
• Epithelial-to-mesenchymal transition (EMT) contributes to fibrotic replacement of follicles
• PPAR-γ deficiency in eHFSCs has been identified as a contributing mechanism — PPAR-γ is essential for maintaining healthy follicles and sebaceous glands
• Perifollicular lamellar fibrosis replaces the destroyed follicular unit, resulting in permanent alopecia

Potential Triggers

• Medications: checkpoint inhibitors (anti-PD-1/PD-L1), beta-blockers, thiazides, ACE inhibitors, gold salts
• Infections: hepatitis C virus, HIV
• Hormonal factors: possible role in FFA (postmenopausal predominance, association with hormone replacement therapy)
• Environmental factors: suspected for FFA (sunscreen ingredients, leave-on cosmetics — epidemiologically associated but not proven)

Classic LPP

• Multifocal patches of cicatricial alopecia, predominantly vertex and parietal scalp
• Active margins show perifollicular erythema and follicular hyperkeratosis
• Central areas: smooth, shiny, porcelain-white atrophic scars with complete absence of follicular ostia
• Symptoms: pruritus (most common), trichodynia, burning sensation
• Positive anagen pull test at active margins
• May be associated with lichen planus at cutaneous, mucosal, or ungual sites in up to 50% of patients

Frontal Fibrosing Alopecia (FFA)

• Progressive, symmetric recession of the frontotemporal and sometimes occipital hairline
• Band-like zone of scarring alopecia at the frontal hairline, 1–8 cm in width
• Loss of eyebrows (>80%), eyelashes, and facial vellus hair
• Body hair loss (axillary, limb, pubic) reported in up to 40%
• Facial papules (non-inflammatory, flesh-colored) in approximately 14%
• Lonely hair sign on trichoscopy: isolated terminal hairs in a scarred field
• Predominantly postmenopausal women, but increasingly recognized in premenopausal women and men

Graham-Little-Piccardi-Lassueur Syndrome

• Triad: (1) cicatricial alopecia of the scalp, (2) non-scarring alopecia of the axillae and groin, (3) follicular keratotic papules (lichen spinulosus-like) on the trunk and extremities
• Extremely rare; predominantly in women
• Often associated with nail lichen planus

Trichoscopic findings are critical for diagnosis and monitoring:

Active disease:

• Peripilar casts (cylindrical, tubular scales around hair shafts) — most characteristic finding
• Perifollicular erythema (violaceous perifollicular halos)
• Blue-grey dots in target-pattern arrangement — hallmark of LPP
• Milky-red areas
• Arborizing (thin, branching) vessels
• Tufted follicles (≥5 hairs emerging from a single follicular opening)

End-stage disease:

• Fibrotic white dots that coalesce into ivory-white structureless areas
• Complete absence of follicular openings
• No hair shafts in scarred zones

Differentiating LPP from FFA on trichoscopy:

• LPP: blue-grey dots in target arrangement, tufted hairs, perifollicular erythema more prominent
• FFA: lonely hair sign, loss of vellus hairs, perifollicular erythema at the hairline recession margin

Scalp biopsy is essential for definitive diagnosis. Optimal technique: 4 mm punch biopsy from an active, symptomatic area at the margin of a bald patch with perifollicular erythema and positive pull test. Both horizontal and vertical sections are informative.

Characteristic findings:

• Band-like (lichenoid) lymphocytic infiltrate at the infundibulum and isthmus of the hair follicle
• Interface dermatitis: vacuolar degeneration and dyskeratosis of basal keratinocytes of the outer root sheath
• Colloid bodies (Civatte bodies) — apoptotic keratinocytes
• Perifollicular concentric lamellar fibrosis (early sign)
• End-stage: fibrous tracts (fibrous stellae) replacing follicular units, reduced follicular density, absence of sebaceous glands
• Wedge-shaped fibrosis pattern, distinct from the columnar fibrosis of discoid lupus

Direct immunofluorescence (DIF):

• Globular deposits of IgM (colloid bodies) at the dermal-epidermal junction of the follicle
• Distinguishes LPP from discoid lupus erythematosus, which shows a continuous linear band of immunoglobulin and complement at the basement membrane zone ("lupus band")

LPPAI (Lichen Planopilaris Activity Index)

Validated composite score (Chiang et al., 2010) quantifying:

• Symptoms: pruritus, pain, burning (scored 0–3 each)
• Signs: perifollicular erythema, perifollicular scaling (scored 0–3 each)
• Anagen pull test (0 or 1)
• Spreading/progression (0 or 1)
• Total LPPAI score used to monitor treatment response; decrease indicates improvement

Condition	Key Differentiating Features
Discoid lupus erythematosus	Adherent scale, follicular plugging, dyspigmentation, positive lupus band on DIF, large yellow hyperkeratotic dots on trichoscopy
Central centrifugal cicatricial alopecia	Vertex-centered, women of African descent, premature desquamation of inner root sheath on histology
Folliculitis decalvans	Neutrophilic infiltrate, tufted folliculitis with pustules, crusting; positive bacterial cultures
Pseudopelade of Brocq	"Footprints in the snow" pattern, minimal inflammation, controversial entity
Alopecia areata	Non-scarring, exclamation point hairs, preserved follicular ostia
Fibrosing alopecia in a pattern distribution (FAPD)	LPP superimposed on androgenetic alopecia pattern

First-Line: Topical and Intralesional Therapy

• Clobetasol propionate 0.05%: Applied to active areas once or twice daily. First-line for localized disease.
• Intralesional triamcinolone acetonide 5–10 mg/mL: Injected at the active inflammatory margins every 4–6 weeks. Effective for focal disease.
• Tacrolimus 0.1% ointment: Steroid-sparing alternative; applied to active areas.
• Topical minoxidil 5%: Adjunctive — does not address inflammation but supports density of remaining follicles.

Second-Line: Systemic Therapy

• Hydroxychloroquine 200 mg twice daily: Most commonly prescribed systemic agent. LPPAI improvement in 69% at 6 months, 83% at 12 months (Chiang et al., 2010). Onset of response typically within 3–6 months. Monitor: ophthalmologic screening (baseline and annual for retinal toxicity per AAO guidelines), CBC, LFTs.
• Methotrexate 15 mg/week: Highest responder rate in retrospective data (79.2% moderate-to-good response). Well-tolerated long-term. Monitor: CBC, LFTs, renal function. Supplement with folic acid.
• Doxycycline 100 mg twice daily: Anti-inflammatory; modest efficacy as monotherapy; useful as adjunct.

Third-Line: Refractory Disease

• Cyclosporine 3–5 mg/kg/day: Effective (69–71% response) but high discontinuation rate (~91%) due to adverse effects (nephrotoxicity, hypertension). Best used short-term for rapid disease flares.
• Mycophenolate mofetil 1–1.5 g twice daily: Immunosuppressive; for cases refractory to hydroxychloroquine and methotrexate.
• Pioglitazone 15–30 mg daily: PPAR-γ agonist; targets the specific molecular defect in LPP. Improvement in 71% of patients (Peterson et al., 2019). Side effects: peripheral edema, weight gain. Can be used as monotherapy or adjunct.
• JAK inhibitors (tofacitinib, baricitinib): Block the IFN-γ/JAK-STAT pathway driving follicular inflammation. Case series show efficacy in refractory LPP; not yet standard of care.
• Retinoids (acitretin): Better response in FFA (74%) than classic LPP (39%).

Hair Transplantation

• Feasible after sustained disease remission (minimum 2 years of quiescence recommended)
• Classic LPP: 75% positive outcomes in systematic review (Lee et al., 2021)
• FFA: 29% positive outcomes — lower success rate
• Important caveat: hair transplantation has been reported to trigger LPP or FFA in susceptible individuals (median 16 months post-procedure)

Treatment Algorithm

1. Mild/localized: Superpotent topical corticosteroids + intralesional triamcinolone ± topical minoxidil
2. Moderate-severe or progressive: Add hydroxychloroquine 200 mg BID; assess at 6 months
3. HCQ failure: Switch to methotrexate 15 mg/week or cyclosporine (short-term bridging)
4. Refractory: Consider pioglitazone, mycophenolate, JAK inhibitors
5. Maintenance: Sustained treatment required; discontinuation associated with ~30% flare rate
6. Quiescent + cosmetic concern: Hair transplant after ≥2 years stable remission

FFA-Specific Considerations

• Ophthalmologic monitoring essential if hydroxychloroquine used (FFA patients are often postmenopausal — cumulative dose matters)
• 5-alpha reductase inhibitors (dutasteride, finasteride) have been used with variable success
• Intralesional triamcinolone along the hairline recession margin

Pediatric

• LPP in children is rare; when present, biopsy is strongly recommended to confirm diagnosis
• Treatment follows adult protocols at weight-adjusted doses

Pregnancy

• Hydroxychloroquine is considered safe in pregnancy (FDA Category C; extensive lupus data)
• Methotrexate, mycophenolate, and acitretin are contraindicated in pregnancy

• Natural history: Chronic, relapsing course with unpredictable periods of activity and quiescence
• Permanent hair loss: Scarred follicles cannot regenerate; early treatment is critical
• Treatment response: Most patients achieve disease stabilization with appropriate therapy; complete remission is uncommon
• Relapse: ~30% flare rate upon treatment discontinuation; long-term maintenance therapy (>20 months) reduces relapse risk
• Psychosocial impact: Significant — anxiety, depression, reduced quality of life. Support groups and psychological counseling should be offered
• Malignancy risk: Unlike oral lichen planus, LPP does not carry a known risk of malignant transformation

• A positive pull test at the margins of an alopecic patch in the setting of perifollicular erythema and scaling strongly suggests active LPP
• Blue-grey dots on trichoscopy in a target-pattern arrangement are highly characteristic
• Always examine the eyebrows, body hair, and nails — concomitant involvement changes the subtype classification
• Biopsy from the active edge, not the scarred center — the center shows only end-stage fibrosis
• Consider FAPD (fibrosing alopecia in a pattern distribution) when LPP and androgenetic alopecia coexist — this hybrid entity is increasingly recognized
• Hydroxychloroquine requires 3–6 months for clinical effect — counsel patients on the expected timeline before switching therapy
• LPP following checkpoint inhibitor therapy (anti-PD-1) is increasingly reported — obtain a thorough medication history