[Erysipelas without fever or biologic inflammation during tocilizumab therapy]

Tocilizumab (TCZ) is a monoclonal antibody that inhibits the interleukin 6 (IL-6) signalling pathway. This treatment is extremely effective in rheumatoid arthritis (RA), which may well be accompanied by serious infections presenting misleading clinical pictures. Herein we report a case of a typical bacterial dermo-hypodermitis in a female patient treated with TCZ.

An 80-year-old woman treated with methotrexate (MTX) and TCZ for RA presented dermo-hypodermitis on her left leg 8 days after receiving her 13th infusion of TCZ. She exhibited neither fever nor biological inflammatory syndrome. Oral amoxicillin (3g/d) was initiated on an outpatient basis. Two weeks later, the patient was apyretic and her laboratory results were normal, although local inflammatory signs persisted. TCZ infusion was postponed and she was given intravenous amoxicillin (4g/d) for 2days, followed by oral amoxicillin, resulting in rapid recovery. Subsequent courses of TCZ were administered without incident.

During the course of treatment with TCZ, this patient presented delineated bacterial cellulitis in the form of erysipelas, which was noteworthy on account of the absence of fever and of biological inflammatory syndrome. While there have been reports of severe cases of cellulitis during TCZ treatment, to our knowledge, there have been none of erysipelas. Attenuation of local and systemic inflammatory symptoms is widely reported, and is directly associated with the anti-IL-6 action of TCZ. Patients with RA are especially susceptible to opportunistic or severe infections as a result of the disease itself and of associated treatments, and increased vigilance is called for with regard to infections that may be transformed and potentially more severe as a result of TCZ.