and hypertrophic that are less common (▶ Fig. 1.9 and ▶ Fig. 1.10), and the bullous and pigmented (▶ Fig. 1.11 and ▶ Fig. 1.12) that are rare. Frequently, the erosive and atrophic forms involve the gingiva in the pattern of desquamative gingivitis.
Clinically, the cutaneous lichen planus appears as small, flat, polygonal, shiny papules with characteristic violaceous color, associated by pruritus (▶ Fig. 1.13). The lesions are distributed in a symmetrical pattern, more frequently on the flexor surfaces of the forearms and wrists, the neck, the back, and the sacral area. Linear lesions may develop after scratching the skin (Koebner’s phenomenon). Genitalia and nails may also be affected. Oral lichen planus may follow a course of remissions and exacerbations. The buccal mucosa, tongue, gingiva, and lips are most commonly affected. Middle-aged individuals are more frequently affected, with a female-to-male ratio of 2:1. The diagnosis usually is based on clinical grounds alone. The prognosis of oral lichen planus is usually good, as possibility of malignant transformation is very rare and controversial.
Laboratory tests: Biopsy and histologic examination are helpful. Direct immunofluorescence can also be used.
Differential diagnosis: Fordyce’s spots, chemical burn, candidiasis, lichenoid reaction to drug or dental material, cinnamon contact stomatitis, geographic tongue, leukoplakia, erythroplakia, graft versus host disease, discoid lupus erythematosus, secondary syphilis, mucous membrane pemphigoid, other chronic bullous diseases, and chronic ulcerative stomatitis.
Treatment: Mild, asymptomatic forms of lichen planus do not need therapy. Systemic corticosteroids (e.g., prednisolone 20–40 mg/day) are the drugs of choice in severe, symptomatic cases, particularly in the erosive form. Topical corticosteroids and/or tacrolimus in a 0.5% adhesive ointment form are suggested in less severe cases. The topical use of antiseptic mouthwashes should be avoided.
Fig. 1.7 Lichen planus, reticular type on the buccal mucosa.
Fig. 1.8 Lichen planus, erosive type on the dorsum of the tongue.
Fig. 1.9 Lichen planus, atrophic type on the dorsum of the tongue.
Fig. 1.10 Lichen planus, hypertrophic lesions with a central erosion on the buccal mucosa.
Fig. 1.11 Lichen planus, bullous type on the buccal mucosa.
Fig. 1.12 Lichen planus, pigmented lesion on the buccal mucosa.
Fig. 1.13 Lichen planus, typical lesions on the forearm.
1.4 Lichenoid Reactions
Definition: Lichenoid reactions are a heterogeneous group of lesions of the oral mucosa that exhibit clinical and histopathological similarities to oral lichen planus, but have a different clinical course.
Etiology: Persistent, chronic contact of the oral mucosa with amalgam restorations that have been oxidized, may lead to hypersensitivity or toxic reaction, usually due to mercury and rarely to other trace metals (zinc, copper, silver, and tin). Similar reactions may appear after contact with composite resin, dental plaque accumulation, and systemic drug administration.
Clinical features: Clinically, lichenoid reaction appears as white and/or erythematous lesions, usually associated with peripheral, irregular delicate white striae (▶ Fig. 1.14 and ▶ Fig. 1.15). Occasionally, erythema and erosions may develop, associated with pain and a burning sensation, particularly to certain foods and spices. Characteristically, the lesions develop exactly at the sites of contact of the oral mucosa with the restorative material, and do not migrate to other sites. The clinical and histopathological features are similar to lichen planus. The buccal mucosa and the lateral margins of the tongue are the most frequently affected. Classically, the lesions disappear after removal of the responsible restorative material. The diagnosis is usually based on the history and clinical features.
Laboratory tests: Histopathologic examination is useful. In addition, a skin punch biopsy to detect the suspicious material may be helpful.
Differential diagnosis: Lichen planus, discoid lupus erythematosus, drug-induced lesions, graft versus host disease, cinnamon contact stomatitis, chronic biting, leukoplakia, and mucous membrane pemphigoid.
Treatment: Replacement or polishing of old restorative material is recommended. In serious cases topical or systemic steroids in low dose for 2 to 3 weeks can be helpful.
Fig. 1.14 Lichenoid reaction of the buccal mucosa caused by contact with an amalgam restoration.
Fig. 1.15 Erosion and white areas of the tongue caused by contact with amalgam restorations.
1.5 Linea Alba
Definition: Linea alba is a relatively common alteration of the buccal mucosa, and is usually bilateral.
Etiology: Mechanical pressure or irritation from the buccal surface of the teeth along with sucking is the etiologic factor.
Clinical features: Clinically, linea alba presents as unilateral or usually bilateral linear elevation of normal or slightly whitish color and normal consistency on palpation (▶ Fig. 1.16). Characteristically, it appears on the buccal mucosa along the occlusal level of the teeth. Linea alba, occasionally, may be scalloped and is often seen in obese individuals. The diagnosis is based exclusively on the clinical features.
Differential diagnosis: Chronic biting, leukoedema, candidiasis, leukoplakia, and cinnamon contact stomatitis.
Treatment: No treatment is required.
Fig. 1.16 Linea alba.
