title: [Psoriatic arthritis during rituximab treatment of granulomatosis with polyangiitis: a new paradoxical side effect?].
abstract: BACKGROUND
  Rituximab is a monoclonal antibody targeting the CD20 molecule of the B lymphocyte. Its efficacy has been recently reported in ANCA-associated vasculitis. We report a case of psoriatic arthritis that occurs during a treatment with rituximab in granulomatosis with polyangiitis.
  
  
  METHODS
  A 66-year-old woman, without past history of psoriasis, presented with a relapsing granulomatosis with polyangiitis in July 2010 with sinus and lung involvement. Treatment with rituximab was started, allowing a complete remission in 6 months. Two months after the first two infusions of rituximab she developed asymmetric arthritis of 3 distal interphalangeal joints. A few months later, the clinical presentation showed asymmetrical arthritis of the hands and wrists and dactylitis. Standard radiographs and MRI showed an inflammatory impairment according with psoriatic arthritis.
  
  
  CONCLUSIONS
  Accountability of rituximab was retained in the development of the disease given the chronology of psoriatic arthritis development. It may be a paradoxical reaction, by analogy to those observed in anti-TNFα.
authors.affiliation: Département de médecine interne, CHU de Rouen, 76031 Rouen cedex, France. Electronic address: audrey.aussy@gmail.com.
authors.forename: A
authors.initials: A
authors.lastname: Aussy
authors.affiliation: Département de médecine interne, CHU de Rouen, 76031 Rouen cedex, France.
authors.forename: N
authors.initials: N
authors.lastname: Girszyn
authors.affiliation: Inserm U905, service de rhumatologie, CIC-CRB020, CHU de Rouen, 76031 Rouen cedex, France.
authors.forename: T
authors.initials: T
authors.lastname: Vandhuick
authors.affiliation: Département de médecine interne, CHU de Rouen, 76031 Rouen cedex, France.
authors.forename: I
authors.initials: I
authors.lastname: Marie
authors.affiliation: Inserm U905, service de rhumatologie, CIC-CRB020, CHU de Rouen, 76031 Rouen cedex, France.
authors.forename: O
authors.initials: O
authors.lastname: Vittecoq
authors.affiliation: Département de médecine interne, CHU de Rouen, 76031 Rouen cedex, France; Inserm U 1096, CHU de Rouen, 76031 Rouen cedex, France.
authors.forename: H
authors.initials: H
authors.lastname: Lévesque
authors.affiliation: Département de médecine interne, CHU de Rouen, 76031 Rouen cedex, France; Inserm U 1096, CHU de Rouen, 76031 Rouen cedex, France.
authors.forename: Y
authors.initials: Y
authors.lastname: Benhamou
mesh_terms: D000368:Aged; D015535:Arthritis, Psoriatic / Q000139:chemically induced* / Q000175:diagnosis; D005260:Female; D014890:Granulomatosis with Polyangiitis / Q000188:drug therapy*; D006801:Humans; D007155:Immunologic Factors / Q000009:adverse effects* / Q000627:therapeutic use; D000069283:Rituximab / Q000009:adverse effects* / Q000627:therapeutic use; D016896:Treatment Outcome
chemical_list: D007155:Immunologic Factors; D000069283:Rituximab
keywords: Effet paradoxal; Granulomatosis with polyangiitis; Paradoxical effect; Polyangéïte avec granulomatose; Psoriatic arthritis; Rhumatisme psoriasique; Rituximab