Multiple halo naevi associated with tocilizumab

Tocilizumab, a humanized monoclonal antibody directed against the interleukin (IL)‐6 receptor, is approved for the treatment of rheumatoid arthritis and juvenile idiopathic arthritis (JIA). We describe a case of multiple halo naevi occurring in a patient with a history of JIA treated with tocilizumab. IL‐6 is a key cytokine in the setting of cancer through its effects on angiogenesis and inhibition of adaptive anti‐tumour immunity. IL‐6 also plays a role in melanocyte function, and increased levels have been noted in vitiligo skin, where it is a paracrine inhibitor of melanocytes. Tocilizumab may therefore lead to the development of halo naevi secondary to subsequent activation of adaptive immunity. Alternatively, as tocilizumab results in increased serum IL‐6 levels, the epidermal cytokine profile is altered. Increased levels of IL‐6 may therefore have a direct inhibitory effect on melanocytes, where access by tocilizumab may be limited due to differential size difference.