What is the recommended workup for patients with lichen planus in rheumatology?

Rheumatologic Workup for Lichen Planus

Biopsy is the cornerstone of the rheumatologic workup for lichen planus, mandatory for confirming diagnosis and ruling out malignancy, particularly in atypical presentations or when systemic immunosuppressive therapy is being considered. 1, 2

Essential Diagnostic Confirmation

• Perform a 4-mm punch biopsy in all cases where diagnosis is uncertain, features are atypical, or when planning second-line systemic therapy 1, 3
• Biopsy is particularly critical when evaluating for autoimmune overlap syndromes, as lichen planus shows strong associations with other autoimmune conditions 1
• Histological examination must be obtained if there is suspicion of neoplastic change, including persistent hyperkeratosis, erosion, erythema, or new warty/papular lesions 1

Screening for Autoimmune Associations

The autoimmune theory is one of the most accepted etiologies for lichen planus, making rheumatologic screening essential 1:

• Screen for organ-specific autoantibodies, as these are frequently found in lichen planus patients 1
• Evaluate for concurrent autoimmune diseases, particularly diabetes mellitus, vitiligo, and alopecia areata, which occur in up to 22% of lichen planus patients 1
• Document that 42% of lichen planus patients have detectable autoantibodies and 60% have at least one autoimmune-related phenotype 1

Site-Specific Assessment

Oral and Mucosal Evaluation

• Examine oral mucosa for reticular white lines (Wickham striae), erosions, or erythematous patches 3
• Document any odynophagia, dysphagia, dysgeusia, or sensitivity to hot/spicy foods 4
• Recognize that oral lichen planus is classified as an oral potentially malignant disorder with low but real risk of squamous cell carcinoma transformation 4

Genital Assessment

• In females, look for figure-eight pattern of involvement around vulva and anus, with fragile, thinned, atrophic skin 1
• Assess for pruritis, dyspareunia, dysuria, and pain on defecation 1
• In males, examine glans, prepuce, and meatus for white discoloration, phimosis, or urethral involvement 1
• Note that 20% of males with lichen sclerosus (often confused with lichen planus) have urethral involvement requiring urologic evaluation 1

Cutaneous and Nail Examination

• Document classic "six P's": planar (flat-topped), purple, polygonal, pruritic papules and plaques, typically on flexor surfaces of wrists, forearms, and legs 3
• Examine for Wickham striae overlying lesions 3
• Assess nail involvement carefully, as nail lichen planus can lead to permanent destruction requiring early aggressive treatment 5

Extent and Severity Documentation

• Quantify body surface area involvement to determine if systemic therapy is warranted (approximately 20% of patients have widespread disease requiring systemic treatment) 6
• Document impact on quality of life, particularly psychosexual function when genital disease is present 7
• Assess for extragenital involvement (occurs in 15-20% of cases), including trunk, axillae, buttocks, lateral thighs, scalp, hands, feet, and nails 1

Critical Pitfall to Avoid

Do not confuse lichen planus with lichen sclerosus, as they have different natural histories and malignancy risks. Lichen sclerosus has documented association with squamous cell carcinoma (particularly in genital disease), while lichen planus has lower but present malignant potential primarily in oral lesions 1, 4. When features overlap or diagnostic uncertainty exists, biopsy becomes absolutely mandatory 1.