lichen planus

Last edited 09/2021 and last reviewed 04/2022

This is a condition of unknown aetiology characterized by intensely pruritic shiny, flat topped, violaceous, polygonal papules that are usually seen on the flexural surfaces of the wrists, arms and legs (1). Other affected sites include:

• trunk and thighs (1)
• mucous membranes are often affected e.g. - buccal mucosa, female genitalia
• penis - mostly annular lesions
• scalp - will lead to scarring if untreated.
• nails (2)

It commonly affects people between the ages of 30 and 60 years and can be seen in both sexes (1). Lichen planus lesions may evolve gradually over several weeks or may develop rapidly (2). It may present as:

• Grouped
• Annular
• Generalized lesions (1)

This is a condition of unknown aetiology characterized by intensely pruritic flat topped papules that are usually seen on the inner aspect of the elbows and wrists. The mucous membranes are often affected.

Ulcerative lichen planus in the mouth may predispose to squamous cell carcinoma - in one retrospective study of 229 patients with oral lichen planus managed at a tertiary referral centre, four patients (1.7 percent) developed oral squamous-cell carcinoma during the follow-up period (3).

Click here for example images of lichen planus

Notes:

• HLA halotypes (e.g. HLA-DR1 in cutaneous LP) and rare cases of familial LP suggest that genetic factors may have a role in susceptibility
• autoimmune disorders like ulcerative colitis and alopecia areata occur more frequently in LP patients than controls
• is a significant association between Hepatitis C (HCV) infection and LP, although there is no known explanation for this
• many drugs (e.g. gold, penicillamine, antimalarials) and amalgam fillings can cause lichenoid reactions

Reference:

• 1. Hsu S, Feasel A.M. Photo Quiz : Koebner Streak. AAFP 2002; 65(3)
• 2. Primary Care Dermatology Society (UK). Lichen planus
• 3. J Am Dent Assoc. 2001 Jul;132(7):901-9
• 4. Bermejo-Fenoll A et al. Biopsy of the buccal mucosa in oral lichen planus. J Am Dent Assoc 2007; 138(7):957-962
• 5. Shengyuan L, songpo Y, Wen W, Wenjing T, Haitao Z, Binyou W. Hepatitis C virus infection and lichen planus: a reciprocal association determined by meta-analysis. Arch dermatol. 2009:145 (9):1040-1047.
• 6. Usatine R, Tinitigan M. Diagnosis and Treatment of Lichen Planus. American Family Physician. 2011 Jul1;84 (1):53-60.