Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.


Incomplete Thymic Involution in Systemic Sclerosis and Rheumatoid Arthritis.

Meunier1,  Marine, Bazeli2,  Ramin, Avouac1,  Jerome, Feydy2,  Antoine, Drape2,  jean-Luc, Kahan1,  Andre, Allanore1,  Yannick

Paris Descartes University, Rheumatology A department, Cochin Hospital, Paris, France
Paris Descartes University, Radiology B department, Cochin Hospital, Paris, France

Background/Purpose:

The thymus is a central lymphatic organ responsible for many immunological functions, including the production of mature functional T cells and the induction of self-tolerance. Several reports have suggested a potential association between thymus alterations and some immune-mediated rheumatic diseases, with radiological thymic alterations, such as incomplete thymic involution, thymic hyperplasia or thymoma., However, data regarding thymus alterations and systemic sclerosis (SSc) or rheumatoid arthritis (RA) are sparse. The aim of this study was to evaluate by chest CT scans the frequency and characteristics of incomplete thymic involution, in patients with SSc and RA, together with a non-autoimmune group of controls.

Methods:

We performed a retrospective observational study between 2006 and 2009 including 161 patients who were at least 40 years old. These patients comprised 96 SSc patients (median age 59 years, 80% women) and 65 RA patients (median age 57 years, 88% women). All patients had a systematic chest CT-scan performed during the usual follow-up of their disease. SSc and RA patients were compared with 32 healthy controls (median age 63 years, 62% women) free of autoimmune disease. For the purpose of our study, complete involution of the thymus was defined as the absence of a residual thymus or a gland thickness, corresponding to the short axis on the axial slice, of less than 7 mm. We defined incomplete involution of the thymus as a residual thymic tissue more than 7 mm thick.

Results:

The frequency of incomplete thymus involution was significantly higher in SSc and RA patients (respectively 15% and 14%) than in the control group (0%; p<0.05). SSc patients with incomplete thymic involution were younger than SSc patients with complete thymic involution (47 (39–80) years vs. 59 (39–87) years; p=0.002) and more likely to have pulmonary fibrosis with restrictive syndrome (24% vs. 0%, p=0.03). There was no correlation between incomplete thymic involution and other SSc-related disease characteristics, especially specific autoantibodies. In RA patients, incomplete thymic involution was more frequently associated with treatment with biologics (100% vs. 62%; p=0.02) and an absence of antinuclear antibodies (0% vs. 32%, p=0.05).

Conclusion:

The prevalence of incomplete thymic involution to be higher in SSc and RA patients than in the control group. Our results suggest that incomplete thymic involution is linked to disease severity. Further larger studies are required to confirm this association and clarify the pathological significance of incomplete thymic involution in autoimmune diseases.

To cite this abstract, please use the following information:
Meunier, Marine, Bazeli, Ramin, Avouac, Jerome, Feydy, Antoine, Drape, jean-Luc, Kahan, Andre, et al; Incomplete Thymic Involution in Systemic Sclerosis and Rheumatoid Arthritis. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :690
DOI:

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