Epidemiology and Etiology
AGE OF ONSET 30 to 60 years.
SEX Females > males.
ETIOLOGY Idiopathic in most cases but cell-mediated immunity plays a major role. Majority of lymphocytes in the infiltrate are CD8+ and CD45Ro+ (memory) cells. Drugs, metals (gold or mercury), or infection (hepatitis C virus) 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 lichen planus (LP) (see Section 22).
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.
SKIN LESIONS Papules, flat-topped, 1 to 10 mm, sharply defined, shiny (Fig. 14-14). Violaceous, with white lines (Wickham striae) (Fig. 14-14A), seen best with hand lens after application of a drop of mineral oil. Polygonal or oval (Fig. 14-14B). Grouped (Figs. 14-14and 14-15), annular, or disseminated scattered discrete lesions when generalized (Fig. 14-16). In dark-skinned individuals, postinflammatory hyperpigmentation is common. May present on lips and in a linear arrangement after trauma (Koebner or isomorphic phenomenon) (Fig. 14-17).
Sites of Predilection Wrists (flexor), lumbar region, shins (thicker, hyperkeratotic lesions), scalp, glans penis (see Section 34), and mouth (see Section 33).
Hypertrophic Large thick plaques arise on the dorsum of hands (Fig. 14-15A), foot (Fig. 14-15B), and shins; more common in black males. Although typical LP papule is smooth, hypertrophic lesions may become hyperkeratotic.
Atrophic White-bluish, well-demarcated papules and plaques with central atrophy.
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 31).
Vesicular Vesicular or bullous lesions may develop within LP patches or independent of them within normal-appearing skin. In rare variants, there are direct immunofluorescence findings consistent with bullous pemphigoid, and the sera of these patients contain bullous pemphigoid IgG autoantibodies (see Section 6).
Pigmentosus Hyperpigmented, dark-brown macules in sun-exposed areas and flexural folds. In Latin Americans and other dark-skinned populations. Significant similarity with ashy dermatosis (see Fig. 13-11).
Actinicus Papular LP lesions arise in sun-exposed sites, especially the dorsa of the 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 (see Section 33).
Reticular LP Reticulate (netlike) pattern of lacy white hyperkeratosis on buccal mucosa (see Section 33), lips, and tongue, gingiva.
Erosive or Ulcerative LP Superficial erosion with/without overlying fibrin clot; occurs on tongue and buccal mucosa (see Section 33); shiny red painful erosion of gingiva (desquamative gingivitis) (see Section 33) or lips. Carcinoma may very rarely develop in mouth lesions.
GENITALIA Papular (see Section 34) agminated, annular, or erosive lesions arise on the penis (especially glans), scrotum, labia majora, labia minora, and vagina.
HAIR AND NAILSScalp Follicular LP or atrophic scalp skin with scarring alopecia. (See Sections 31 and 32.)
Nails Destruction of nail fold and nail bed with longitudinal splintering (see Section 32).
Lichen Planus-Like Eruptions
LP-like eruptions closely mimic typical LP, both clinically and histologically. They occur as a clinical manifestation of chronic GVHD, in dermatomyositis (DM), 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 (see Section 23).
Laboratory Examination
DERMATOPATHOLOGY Inflammation with hyperkeratosis, increased granular layer, irregular acanthosis, liquefaction degeneration of the basal cell layer, and band-like mononuclear infiltrate that hugs the epidermis. Keratinocyte apoptosis (colloid, Civatte bodies) 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.
Clinical findings confirmed by histopathology.
Papular LP Chronic cutaneous lupus erythematosus (CCLE), psoriasis, pityriasis rosea, eczematous dermatitis, and lichenoid GVHD; single lesions: superficial basal cell carcinoma or Bowen disease (in situ squamous cell carcinoma).
Hypertrophic LP Psoriasis vulgaris, lichen simplex chronicus, prurigo nodularis, stasis dermatitis, and Kaposi sarcoma.
MUCOUS MEMBRANES Leukoplakia, pseudomembranous candidiasis (thrush), HIV-associated hairy leukoplakia, lupus erythematosus (LE), bite trauma, mucous patches of secondary syphilis, pemphigus vulgaris, or bullous pemphigoid (see Section 33).
Drug-Induced LP See Section 23.
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.
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/d.
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.
Mycophenolate mofetil, hydroxychloroquine, heparin analogues (enoxaparin) in low doses have antiproliferative and immunomodulatory properties; azathioprine.