Lichen Planus: Scalp, Symptoms & Dermoscopic Features

• Lichen planus can manifest in various sites, including the scalp, mucosa, nails, flexural areas, and palms/soles.

Lichen Planus of the Scalp

• Also known as lichen planopilaris.
• More common in females.
• Includes lichen planopilaris, frontal fibrosing alopecia, and GLPLS (Graham-Little-Piccardi-Lassueur syndrome).
• Classic lichen planopilaris involves keratotic follicular papules forming plaques on the scalp, leading to scarring alopecia, and affects the vertex scalp.
• Dermoscopic features include the absence of follicular openings, white patches, peripilar casts, perifollicular scale, blue-gray dots, perifollicular erythema, and polytrichia.
• Active lesions usually appear within hair-bearing areas at the edge of the alopecic patch.
• Scarring alopecia can be unilesional or multifocal, potentially leading to near-total scalp involvement.
• Frontal fibrosing alopecia is characterized by progressive frontotemporal hairline recession due to inflammatory destruction of hair follicles.
• Eyebrow loss is reported in up to 75% of women with frontal fibrosing alopecia and is typically noninflammatory.
• There has been a rise in frontal fibrosing alopecia cases in recent years.
• Leave-on facial products, including sunscreen, and positive patch test results to fragrances are associated.
• More common in postmenopausal women but can also occur in younger women.
• Characterized by slow progression of frontal hairline recession over years.
• GLPLS is a rare subtype involving cicatricial alopecia of the scalp, nonscarring alopecia of the axilla and groin, and follicular papules on the trunk and extremities.
• Pseudopelade of Brocq is a rare syndrome of scarring alopecia and fibrosis without distinct pathologic features.
• It is generally accepted as the end stage of follicular fibrosis caused by inflammatory dermatoses like lichen planus, lupus erythematosus, pustular folliculitis, fungal infections, scleroderma, and sarcoidosis.

Mucosal Lichen Planus

• Can affect any mucosal surface, commonly the mouth or genitalia.
• Prevalence is around 1% of the adult population.
• Oral involvement occurs in approximately 60% to 70% of patients with lichen planus and may be the only manifestation in 20% to 30% of patients.
• Multiple types of oral lichen planus exist, including reticular, plaque-like, atrophic, papular, erosive or ulcerative, and bullous forms.
• Reticular form is the most common and often asymptomatic, with the buccal mucosa being the most common site.
• Erosive and ulcerative oral lichen planus is most on the tongue, is extremely painful.
• Gingival involvement may manifest as gingival stomatitis or desquamative gingivitis and is the sole manifestation in 8% of oral lichen planus.
• Oral lichen planus is the most common cause of desquamative gingivitis, accounting for 75% of cases.
• Oral lichenoid reactions (OLRs) are clinically and histologically similar to oral lichen planus but have an identifiable cause.
• OLRs are usually seen on the buccal mucosa adjacent to amalgam dental fillings.
• Positive patch test results to mercury, gold, and other metals may be seen.
• Improvement occurs with amalgam removal in patients with OLR, no cutaneous lichen planus, and negative patch test results.
• A unique lichenoid eruption has been described on the tongues of individuals with HIV.
• Characterized by bilateral reticular keratotic or atrophic changes of the buccal mucosa and lichenoid atrophic patches over the dorsal tongue.
• The eruption usually follows zidovudine or ketoconazole intake.
• Esophageal lichen planus is rare and most often affects the proximal esophagus, predominantly affecting middle-aged women.
• Nearly all esophageal lichen planus cases have preceding or concomitant oral lichen planus.
• Clinical clues include progressive dysphagia and odynophagia, prompting a gastroenterology referral for endoscopy.
• Endoscopic findings can include lacy white papules, pinpoint erosions, desquamation, pseudomembranes, and stenosis.
• Esophageal stricture is common and often requires multiple dilations.
• Histologically, esophageal lichen planus shows parakeratosis, epithelial atrophy, and lack of hypergranulosis.
• Esophageal lichen planus often requires systemic immunosuppression with oral corticosteroids.
• Malignant transformation has been described, necessitating regular surveillance with gastroenterology.
• Male genitalia are involved in 25% of lichen planus cases, with the glans penis most commonly affected with annular lesions.
• Anal lesions of mucosal lichen planus present with leukokeratosis, hyperkeratosis, fissuring, and erosions.
• Vulvar and vaginal lichen planus is present in 25% to 60% of patients with oral lichen planus.
• Clinical examination often reveals patches of leukoplakia or erythroplakia, sometimes with erosions, and occasionally, as a more generalized desquamative vaginitis.
• Erosive and atrophic disease is most commonly reported, and vaginal adhesions and labial agglutination may result.
• Vulvovaginal gingival syndrome is a distinct triad of vulvar, vaginal, and gingival disease.
• Characterized by erythema and erosions of the gingivae and tongue and desquamation and erosions of vulva and vagina.
• Other cutaneous sites of involvement include skin (40%), scalp (20%), nails (13%), and esophagus (15%).
• Vulvovaginal gingival syndrome is associated with significant long-term sequelae with nearly 90% of individuals developing fibrosis and stricture.
• Class II HLA DBQ1∗0201 allele has been found in 80% of individuals with vulvovaginal gingival syndrome with a relative risk of 3.71.
• Early and multidisciplinary aggressive topical and systemic immunosuppression needed for optimal outcomes.
• Conjunctival lichen planus may manifest as cicatricial conjunctivitis.
• Histologically, irregular thickening with reduplication of the basement membrane is seen.
• Conjunctival lichen planus is often a diagnostic challenge with significant overlap with cicatricial pemphigoid.
• Long-term sequelae include corneal scarring, symblepharon, blindness, and lacrimal duct stenosis.
• Otic lichen planus is another rare manifestation affecting the external auditory canal and the tympanic membrane.
• Otic lichen planus is more common in women, often has concomitant disease at multiple body sites, and can lead to progressive hearing loss.
• Considered in the differential diagnosis for patients with mucosal or cutaneous lichen planus with persistent, unexplained otorrhea or external auditory canal stenosis.

Lichen Planus of the Nails

• Nail involvement occurs in 10% to 15% of lichen planus patients.
• Limited to the nails is uncommon and, in many cases, is followed by the development of more typical cutaneous or mucosal lesions of lichen planus.
• Rare in children, affecting approximately 5%.
• Three major forms: classic nail lichen planus, 20-nail dystrophy, and idiopathic atrophy of the nails.
• Most common findings include diffuse nail involvement with thinning, longitudinal ridging, and distal nail splitting (onychoschizia).
• Other findings include onycholysis, longitudinal striation with a “sandpaper-like quality” (onychorrhexis), subungual hyperkeratosis, and atrophic or absent nail plates (anonychia).
• Dermoscopy can aid in early diagnosis.
• Disease with prominent inflammation can result in nail loss and scarring.
• Pterygium or forward growth of the eponychia with adherence to the proximal nail plate is a classic finding involving the matrix.
• Dorsal pterygium is an irreversible process and, will likely not improve with treatment.
• Involvement of the nail bed results in elevation of the nail plate and nail splitting.
• Trachyonychia, or uniform roughness of the nails, often affects all 20 nails and follows an indolent course.
• Idiopathic atrophy of the nails is characterized by an abrupt onset and rapidly progressive thinning of the nails with subsequent loss and scarring with or without dorsal pterygium.
• The latter two forms of nail lichen planus are more common in children.
• The differential diagnosis of isolated nail lichen planus includes psoriasis, alopecia areata, atopic dermatitis, and rarely immunobullous diseases.

Inverse Lichen Planus

• The inverse pattern of lichen planus is rare and is characterized by red-brown, discrete papules and flat-topped plaques.
• Commonly affects the flexural areas, including the axillae, inframammary region, and groin.
• May rarely involve antecubital and popliteal areas.
• Findings are often isolated, and involvement of other ectodermal-derived tissues is uncommon.
• Most commonly reported in whites, Asians, and recently Tunisians.
• Absence of involvement in sun-exposed areas.

Palmoplantar Lichen Planus

• Palmoplantar lichen planus is a Palmoplantar lichen planus is rare, difficult-to-diagnose form of lichen planus.
• Approximately 25% of individuals have other areas of cutaneous involvement, most commonly on the anterior shin and malleoli in those with plantar disease.
• Characterized by pruritic, red-purple, scaly plaques with or without hyperkeratosis.
• Wickham striae are absent due to thickness of palmar and plantar skin.
• Four patterns are seen: plaque type, punctate, diffuse keratoderma, and ulcerated.
• Lesions are commonly seen on the internal plantar arch on the feet and the thenar and hypothenar eminence on the hands.
• Yellow, compact keratotic papules or papulonodules are seen on the lateral margins of the fingers and hand surfaces.
• Involvement of the fingertips is uncommon and, if present, raises the possibility of a primary or concomitant dermatitis.
• Lesions often appear callus-like with a faint purple hue and an inflammatory halo.
• The differential diagnosis includes psoriasis, warts, calluses, porokeratosis, hyperkeratotic dermatitis or eczema, tinea, or secondary syphilis.