Abstract
BACKGROUND: Hepatosplenic T-cell lymphoma (HSTCL), a rare and rapidly progressive subtype of peripheral T-cell lymphoma, has been reported following TNF-α-blocker therapy. To better understand this relationship, we conducted an epidemiologic study in the Kaiser Permanente membership. METHODS: The retrospective cohort study was conducted among Northern California members of all ages. The Kaiser Permanente Cancer Registry, supplemented with review of medical charts and pathology slides, was used to identify and confirm cases of HSTCL. Medical histories were obtained, and we computed the standardized incidence rate for the 7-year period 2000-2006, when immunohistochemical staining was fully established throughout the health plan for diagnosing lymphoma. RESULTS: Six cases were diagnosed during 2000-2006, for an annual age-standardized incidence rate of 0.3 (95%CI, 0.11-0.65) per million person-years. One case had a prior diagnosis of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS); another had a prior diagnosis of Crohn's disease treated with steroids, thiopurine and infliximab. CONCLUSION: Prior cases of HIV/AIDS-linked HSTCL are uncommon in the existing literature. Multiple case reports of HSTCL in the setting of Crohn's disease treated with anti-TNF plus thiopurine have been published, but HSTCL is rare, making epidemiologic assessments difficult.