What is lichen planus?

Lichen Planus: Clinical Features, Diagnosis, and Management

Lichen planus (LP) is an inflammatory disorder involving the skin and oro-genital mucous membranes, characterized by T-cell mediated autoimmune reactions that can significantly impact quality of life. 1, 2

Clinical Presentation

• LP classically presents with planar (flat-topped), purple, polygonal, pruritic papules and plaques, often affecting the flexor surfaces of wrists, forearms, and legs 3
• Lesions are frequently covered by lacy, reticular, white lines known as Wickham striae, which are pathognomonic for LP 3
• Oral LP is the most studied phenotype in the setting of HCV infection, with the association being widely described in certain geographical areas 1
• Esophageal LP (ELP) represents the most common dermatologic condition affecting the esophagus and can occur in isolation in approximately 33% of cases 1
• LP can involve multiple body sites simultaneously or independently, including skin, oral cavity, genital mucosa, scalp, and nails 4, 5

Clinical Variants

• Cutaneous LP: Classic presentation with purple, polygonal, pruritic papules on flexor surfaces 3
• Oral LP: Presents as white, lacy patterns (reticular form), painful erosions (erosive form), or plaques (plaque-like form) on the buccal mucosa, tongue, and gingiva 6
• Genital LP: Can cause significant discomfort and scarring in severe cases 4
• Scalp LP (lichen planopilaris): Can lead to permanent scarring alopecia if not treated promptly 5
• Nail LP: Presents with longitudinal ridging, thinning, and sometimes permanent nail destruction 5
• Hypertrophic LP: Characterized by thickened, pruritic plaques typically on the lower extremities 5
• Erosive LP: Particularly affects mucosal surfaces with painful erosions and potential scarring 4

Diagnosis

• Classic cases of LP may be diagnosed clinically based on characteristic appearance 3
• A 4-mm punch biopsy is recommended for atypical presentations or for definitive diagnosis 3
• Histopathology shows band-like lymphocytic infiltrate at the dermal-epidermal junction, hyperkeratosis, and damage to the basal layer 7
• Direct immunofluorescence (DIF) may be helpful in distinguishing LP from other conditions, particularly in mucosal disease 1
• Endoscopic findings in esophageal LP include narrowed caliber of the esophagus, pale edematous mucosa with peeling/sloughing upon contact, and thick white exudates 1

Etiology and Associations

• LP is strongly associated with hepatitis C virus (HCV) infection in certain geographical regions 1
• Autoimmune mechanisms are implicated in pathogenesis, with T-cell mediated reactions playing a central role 2, 7
• LP can be triggered or exacerbated by certain medications, dental materials, and stress 5
• Genetic predisposition may play a role, with LP being more common in certain ethnic groups 2
• LP should be differentiated from lichenoid drug reactions, which can mimic true LP 5

Treatment

• High-potency topical corticosteroids are the first-line therapy for all forms of LP, including cutaneous, genital, and mucosal erosive lesions 3
• Topical tacrolimus appears to be an effective treatment for vulvovaginal LP 3
• Systemic corticosteroids should be considered for severe, widespread LP involving oral, cutaneous, or genital sites 3
• For HCV-associated LP, interferon-based antiviral therapy should be avoided as it can worsen LP or trigger new lesions 1
• Treatment of LP in HCV-positive patients requires a step-wise approach with topical and/or systemic immune-modulating agents, tailored to disease characteristics 1
• Systemic therapy with acitretin (an oral retinoid) or immunosuppressants should be considered for severe LP that does not respond to topical treatment 3
• Regular follow-up is essential due to the chronic nature of the disease and potential for recurrence 3

Prognosis

• Cutaneous LP may resolve spontaneously within one to two years, although recurrences are common 3
• Mucosal LP (oral, genital, esophageal) tends to be more persistent and resistant to treatment 3
• Certain variants like hypertrophic LP and erosive oral LP may have a more chronic pattern 5
• LP can significantly affect quality of life, particularly when involving visible areas or causing pain and discomfort 5
• Regular monitoring is important, especially for oral lesions, due to the small but potential risk of malignant transformation in chronic cases 6

Special Considerations

• LP must be differentiated from lichen sclerosus, which presents with porcelain-white papules and plaques, often with areas of ecchymosis 8
• Lichen sclerosus has a well-established association with squamous cell carcinoma (4-5% risk), emphasizing the importance of biopsy and regular monitoring 2
• In contrast to lichen sclerosus, LP does not typically cause scarring in cutaneous sites but can lead to scarring in mucosal areas and the scalp 1, 5