Recurrent Varicella in an Adult Psoriasis Patient Treated with Etanercept

The use of TNF-blocking agents has been associated with an increased susceptibility to infections [2] . Until now, VZV infections in patients on anti-TNFagents were mainly a paediatric issue, with some cases of severe primary varicella complicated by aseptic meningitis in etanercept-treated children with juvenile rheumatoid arthritis [3] . Herpes zoster [4, 5] and primary varicella [6] , which can be very severe [7] , have also been reported in adults receiving infliximab or adalimumab for Crohn’s disease or rheumatoid arthritis. However, cases of recurrent varicella associated with TNF blockers have never been reported, to the best of our knowledge. In vitro studies have shown that replication of VZV and VZV antigen expression are inhibited by TNF and that this antiviral activity can be completely blocked by monoclonal antibodies against TNF[8] . Atypical recurrent varicella with disseminated lesions and without dermatomal clustering was described in immunocompromised patients with haemopathies and in paediatric renal transplant recipients treated with mycophenolate mofetil [9, 10] . As compared to classical chickenpox and relapsing varicella in children and young adults, disease manifestations were milder with fewer lesions (that all exhibited the same stage of development) [9] . Similar cases of ‘breakthrough varicella’ were also recently reported after immunization with a live attenuated varicella vaccine [11] . In our patient, the history of chickenpox as a child, the positive serology for VZV immunoglobulin G, and the absence of the constitutional symptoms present in primary varicella suggested a reactivation of varicella rather than a new infection. In conclusion, we have described a case of recurrent varicella during etanercept therapy for psoriasis. This entity can thus be added to the list of cutaneous side effects of TNF-blocking agents [5, 12, 13] . Moreover, this case emphasizes the need for psoriasis registries to report rare side effects of psoriasis therapies [14] .