Angioimmunoblastic T cell lymphoma in an ankylosing spondylitis patient treated with etanercept.

Angioimmunoblastic T cell lymphoma (AITL) is a rare non-Hodgkin lymphoma that presents with profound immune dysfunction and immunodeficiency. The clinical and laboratory findings associated with AITL are similar to those of rheumatic disease, and AITL has been reported to be concurrent in patients with several rheumatic diseases. We present one case of AITL occurring in a patient with ankylosing spondylitis (AS) after treatment with etanercept. Constitutional symptoms and aggravation of peripheral arthritis in elderly AS patients may be due not only to flare-ups of AS but also to other complicating diseases, such as lymphoma. Although the occurrence of lymphoma in AS patients treated with etanercept has only rarely been reported, clinicians should keep in mind that instances of aggravation of peripheral arthritis in elderly AS patients occurring after immunosuppressant treatment may be due to other complicating systemic diseases such as AITL, rather than the rheumatic disease itself. Further study is needed in order to investigate whether or not using a TNF-α blocker such as etanercept increases the risk of lymphoma, especially for cases associated with Epstein–Barr virus.