The efficacy of tetracycline antibiotics for treatment of lichen planus: an open-label clinical trial

Conflicts of interest: none declared. Sir, Lichen planus (LP) is an inflammatory condition which may involve skin, hair and mucosa. Although its exact pathogenesis remains unknown, LP probably results from a cell‐mediated immunological response to an unidentified antigen processed by Langerhans cells.1 In this type IV hypersensitivity response, epidermotropic T lymphocytes are stimulated to attack keratinocytes, releasing cytokines that perpetuate the lichenoid tissue reaction and eventual epidermal destruction.2 Classically, a band‐like infiltrate of lymphocytes, histiocytes and Langerhans cells disrupts the dermal–epidermal junction.3 Therapies for cutaneous LP are limited by short‐term efficacy, toxicity and inconvenience. Severe LP responds to retinoids and immunosuppressive agents, but chronic use is often required.4 Some patients may benefit from psoralen and ultraviolet A, although high relapse rates upon discontinuation were reported.5, 6 These and other limitations underscore the need for novel LP treatments with improved side‐effect profiles. The anti‐inflammatory properties of tetracycline antibiotics have previously been studied, with recent evidence pointing to a mechanism involving antibiotic‐mediated inhibition of the T‐lymphocyte response.7 To date, however, no studies have determined the utility of tetracyclines for treatment of cutaneous LP, although one case report described the efficacy of topical tetracycline for erosive oral LP,8 and another showed improvement of lichen planus pemphigoides after treatment with tetracycline and nicotinamide.9 We therefore initiated an open‐label pilot study, investigating the role of tetracycline antibiotics for the treatment of LP, hypothesizing that a dampening of this pathologically robust lymphocytic response may be achieved.