diagnosis and investigation

Last edited 09/2020 and last reviewed 04/2022

Generally the diagnosis is based on clinical findings.

• all potentially involved sites should be examined, such as the oral and genital mucosae, skin, nails and hair
• a drug history is warranted due to the implications of certain drugs in lichenoid reactions. Given the associations with HCV infection, screening for HCV antibodies using ELISA is recommended

Occasionally biopsy is required in atypical cases (in order to demonstrate typical histological features, a biopsy of a fully developed lesion should be taken) (1).

• biopsy is helpful to confirm diagnosis. Direct immunofluorescence on perilesional skin can be useful when bullous lesions, pemphigus or bullous pemphigoid is present

Differential diagnoses of cutaneous LP includes eczema, lichen simplex chronicus, pityriasis rosea, prurigo nodularis and psoriasis. Those of oral lichen planus include bite trauma, leukoplakia and thrush. For lichne planopilaris differential diagnoses include discoid lupus erythematosus, pseudopelade of Brocq, alopecia areata and seborrhoeic dermatitis

Contributor : Dr Maryanne Hammon (GP; 23/3/14)

Reference:

• 1. Primary Care Dermatology Society. Lichen planus (Accessed 2/9/2020)