Lichen planus (LP) is an acute or chronic inflammatory dermatosis involving skin and/or mucous membranes, characterized by flat-topped (Latin planus, "flat"), pink to violaceous, shiny, pruritic polygonal papules on the skin and milky white reticulated papules in the mouth. The features of the lesions have been designated as the four P's—papule, purple, polygonal, pruritic.

Epidemiology and Etiology

Age of Onset

30 to 60 years.

Sex

Females > males.

Race

Hypertrophic LP more common in blacks.

Etiology

Idiopathic in most cases but it is evident that cell-mediated immunity plays a major role. Majority of lymphocytes in the infiltrate are CD8+ and CD45Ro+ (memory) cells. Drugs, metals (gold, mercury), or infection [hepatitis C virus (HCV)] result in alteration in cell-mediated immunity. There could be HLA-associated genetic susceptibility that would explain a predisposition in certain persons. Lichenoid lesions of chronic graft-versus-host disease (GVHD) of skin are indistinguishable from those of LP.

History

Onset

Acute (days) or insidious (over weeks). Lesions last months to years, asymptomatic or pruritic; sometimes severe pruritus. Mucous membrane lesions are painful, especially when ulcerated.

Physical Examination

Skin Lesions

Papules, flat-topped, 1 to 10 mm, sharply defined, shiny (Figs. 7-4 and 7-5). Violaceous, with white lines (Wickham's striae) (Fig. 7-4), seen best with hand lens after application of mineral oil. Polygonal or oval. Grouped (Figs. 7-4 and 7-5), linear (isomorphic phenomenon), annular, or disseminated scattered discrete lesions when generalized (Fig. 7-6). In dark-skinned individuals, postinflammatory hyperpigmentation is common.

Sites of Predilection

Wrists (flexor), lumbar region, shins (thicker, hyperkeratotic lesions), scalp, glans penis, mouth

Variants

Hypertrophic

Large thick plaques arise on the foot (Fig. 7-5A) and shins (Fig. 7-5B); more common in black males. Although typical LP papule is smooth, hypertrophic lesions may become hyperkeratotic.

Follicular

Individual keratotic-follicular papules and plaques that lead to cicatricial alopecia. Spinous follicular lesions, typical skin and mucous membrane LP, and cicatricial alopecia of the scalp are called Graham Little syndrome. (See Section 29.)

Vesicular

Vesicular or bullous lesions may develop within LP patches or independent of them within normal-appearing skin. There are direct immunofluorescence findings consistent with bullous pemphigoid, and the sera of these patients contain bullous pemphigoid IgG autoantibodies (see Section 6).

Actinicus

Papular LP lesions arise in sun-exposed sites, especially the dorsa of hands and arms.

Ulcerative

LP may lead to therapy-resistant ulcers, particularly on the soles, requiring skin grafting.

Mucous Membranes

Some 40 to 60% of individuals with LP have oropharyngeal involvement.

Reticular LP

Reticulate (netlike) pattern of lacy white hyperkeratosis on buccal mucosa (see Fig. 31-16), lips (Fig. 7-7), tongue, gingiva; the most common pattern of oral LP.

Erosive or Ulcerative LP

Superficial erosion with/without overlying fibrin clot; occurs on tongue and buccal mucosa (see Fig. 31-17); shiny red painful erosion of gingiva (desquamative gingivitis) (see Fig. 31-18) or lips (Fig. 7-7). Carcinoma may very rarely develop in mouth lesions.

Genitalia

Papular (see Fig. 32-8), annular, or erosive lesions arise on penis (especially glans), scrotum, labia majora, labia minora, vagina.

Hair and Nails

Scalp

Atrophic scalp skin with scarring alopecia.

Nails

Destruction of nail fold and nail bed with longitudinal splintering (see Fig. 30-10).

Lichen Planus–like Eruptions

Lichen planus–like eruptions closely mimic typical LP, both clinically and histologically. They occur as a clinical manifestation of chronic GVHD; in dermatomyositis, and as cutaneous manifestations of malignant lymphoma but may also develop as the result of therapy with certain drugs and after industrial use of certain compounds

Table 7-1 Agents Inducing Lichen Planus and Lichenoid Reactions

Less-common Inducers

Common Inducers Commonly Prescribed Drugs Uncommonly Prescribed Drugs

Gold salts ACE inhibitors Methyldopa

Beta blockers Calcium channel blockers Antitubercular

Antimalarials Sulfonylurea hypoglycemic agents Sulfasalazine

Thiazide diuretics Nonsteroidal antiinflammatory drugs Heavy metals (arsenic, mercury)

Furosemide Ketoconazole Lithium

Spironolactone Tetracycline Iodides and radiocontrast media

Penicillamine Phenothiazine derivatives Antimony

Carbamazepine

Diagnosis and Differential Diagnosis

Clinical findings confirmed by histopathology.

Skin Lesions

Papular LP

Chronic cutaneous lupus erythematosus, psoriasis, pityriasis rosea, eczematous dermatitis, lichenoid GVHD; superficial basal cell carcinoma, Bowen's disease (in situ squamous cell carcinoma).

Hypertrophic LP

Psoriasis vulgaris, lichen simplex chronicus, prurigo nodularis, stasis dermatitis, Kaposi's sarcoma.

Drug-Induced LP

See Table 7-1.

Mucous Membranes

Leukoplakia, pseudomembranous candidiasis (thrush), HIV-associated hairy leukoplakia, lupus erythematosus, bite trauma, mucous patches of secondary syphilis, pemphigus vulgaris, bullous pemphigoid.

Laboratory Examination

Dermatopathology

Inflammation with hyperkeratosis, increased granular layer, irregular acanthosis, liquefaction degeneration of the basal cell layer, and bandlike mononuclear infiltrate that hugs the epidermis. Degenerate keratinocytes (colloid, Civatte bodies) are found at the dermal-epidermal junction. Direct immunofluorescence reveals heavy deposits of fibrin at the junction and IgM and, less frequently, IgA, IgG, and C3 in the colloid bodies.

Course

Cutaneous LP usually persists for months, but in some cases, for years; hypertrophic LP on the shins and oral LP often for decades. The incidence of oral cancer (squamous cell carcinoma) in individuals with oral LP is increased by 5%; patients should be followed at regular intervals.

Management

Topical Therapy

Glucocorticoids

Topical glucocorticoids with occlusion for cutaneous lesions. Intralesional triamcinolone (3 mg/mL) is helpful for symptomatic cutaneous or oral mucosal lesions and lips.

Cyclosporine and Tacrolimus Solutions

Retention "mouthwash" for severely symptomatic oral LP.

Systemic Therapy

Cyclosporine

In very resistant and generalized cases, 5 mg/kg per day will induce rapid remission, quite often not followed by recurrence.

Glucocorticoids

Oral prednisone is effective for individuals with symptomatic pruritus, painful erosions, dysphagia, or cosmetic disfigurement. A short, tapered course is preferred: 70 mg initially, tapered by 5 mg.

Systemic Retinoids (Acitretin)

1 mg/kg per day is helpful as adjunctive measure in severe (oral, hypertrophic) cases, but usually additional topical treatment is required.

PUVA Photochemotherapy

In individuals with generalized LP or cases resistant to topical therapy.

Reports of Other Successful Treatment

Mycophenolate mofetil, heparin analogues (enoxaparin) in low doses have antiproliferative and immunomodulatory properties; azathioprine.