Pigmented lichen planus

Specialty: Skin.

• pigmented lichen planus
• lichenoid macular hyperpigmentation

Why it occurs

• Uncommon clinical variant of lichen planus of autoimmune etiology characterized by cellular inflammation of the dermal-epidermal junction with massive melanin pigment incontinence, with melanin accumulating within melanophages in the superficial dermis (common in people of high phototype of Asian or Latin American origin)
• Chronic exposure to cumulative solar radiation (stimulates melanogenesis in already inflamed areas)
• Topical application or chronic contact with photosensitizing chemicals or scented cosmetic oils
• Chronic association with the hepatitis C virus (HCV) or other underlying autoimmune liver diseases.

Initial workup

Skin biopsy with a 4 mm punch of the hyperpigmented macula to histopathologically confirm the presence of epidermal atrophy, vacuolar degeneration of the dermal basal layer, and massive pigment incontinence characterized by abundant melanophages loaded with melanin in the papillary dermis, with little or no active lymphocytic infiltrate in late phases. Analytical serology for hepatitis C virus (Anti-HCV), liver transaminases, and thyroid profile.

Standard management

• Tacrolimus 0.1% ointment — first choice topical immunomodulator applied 2 times a day to stop the underlying autoimmune inflammation of the interface, safe for prolonged use on the face
• Hydroxychloroquine — synthetic antimalarial with immunomodulatory properties indicated in cases of rapid progression, doses of 200 to 400 mg daily orally, requiring control ophthalmological examination
• 2% or 4% hydroquinone cream — used with strict caution at night in inactive phases to attenuate residual melanic dermal pigmentation
• Strict daily physical photoprotection with sunscreens containing zinc oxide or titanium dioxide SPF 50+.