Article Text
Summary
IgG4-related disease (IgG4-RD) is a rare but rapidly emerging immune-mediated fibroinflammatory condition that can affect almost any organ. It is typically associated with involvement of organs such as lymph nodes, submandibular glands, orbits, periaortic region and pancreas. However, IgG4-RD presenting primarily as an inflammatory arthritis is much less recognised. We present a rare case of IgG4-RD mimicking psoriatic arthritis. In spite of normal circulating IgG4 plasma levels, a clinical index of suspicion was required to obtain a histopathological diagnosis. The patient’s aggressive arthritis disease did not initially respond to typical disease- modifying agents such as methotrexate. Instead, we report a dramatic response to B cell depletion with rituximab. It is important to emphasise this case as a rare presentation of a rare disease. IgG4-RD is a rapidly emerging condition and the diagnosis should be considered when the alternatives do not seem to fit.
- rheumatology
- drugs: musculoskeletal and joint diseases
- biological agents
- immunology
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Footnotes
Contributors Both authors managed the patient in clinic and on the ward during his admission. Both authors summarised the case, performed a literature review and wrote the case report. ZF is the corresponding author and NM is the senior author of this submission.
Competing interests None declared.
Patient consent Obtained.
Provenance and peer review Not commissioned; externally peer reviewed.