Background Tuberculosis (Tb) is one of the most important diseases accompanying rheumatoid arthritis (RA) (1). The risk of miliary dissemination in post-primary tuberculosis (mTb) is high in rheumatoid arthritis (RA), because of the impaired immune reactivity of elderly patients with autoimmune disease. Introduction of biological therapy (anti-TNF alpha treatment) has generated a new challenge regarding tuberculosis.

Objectives The aim of this study was to determine: the prevalence of post-primary fibrous or fibrocaseous Tb, the incidence of miliary disseminated tuberculosis, the organ involvement by Tb and mTb, and the relationship between Tb and mTb in RA.

Methods A randomized autopsy population of 234 in-patients with RA was studied.

RA was diagnosed clinically according to the ARA criteria.

The post-primary fibrous or fibrocaseous tuberculosis and miliary dissemination of tuberculosis was confirmed histologically.

The link between tuberculosis and disseminated miliary tuberculosis was determined by c²-test.

Results Post-primary fibrous, or fibrocaseous tuberculosis accompanied RA in 27 (11.5%) of 234 cases. Post-primary tuberculosis was localized to the lung. Twelve of 27 post-primary Tb cases were histologically fibrocaseous, and 15 of 27 revealed only fibrous tuberculotic scars.

Eight post-primary fibrous or fibrocaseous tuberculosis cases were complicated by disseminated miliary tuberculosis (3.4% of 234 patients). Proliferative or exudative epithelioid granulomatous tuberculosis involved different organs, such as lungs, liver, spleen, adrenal gland, synovial membrane, vertebrae, pituitary gland, and lymph nodes.

There was a significant association between Tb and mTb (c² = 54.8, p<0.0001, q=1) or fibrocaseous character of Tb and mTb (c² = 68.9, p < 0.0001). There was no significant link between post-primary inactive fibrous tuberculotic scars and miliary dissemination (c² = 2.1, p < 0.14).

Conclusions The risk of tuberculosis is increased in autoimmune diseases.

In Hungary tuberculosis is one of the most important associated diseases accompanying RA with or without miliary dissemination.

In our autopsy material the miliary dissemination of tuberculosis was the result of endogenous exacerbation of Tb, statistically borne out by the high value of Youle¢s association coefficient. Statistics also indicate that the fibrocaseous character of post-primary tuberculotic focus (mostly in the lung) represents a higher risk of miliary dissemination in RA. Inactive fibrous tuberculotic scars did not influence the risk of miliary dissemination. In our cases the miliary dissemination of tuberculosis may be considered a terminal event because of the limited number of granulomas in only a few organs.

Miliary tuberculosis was, beside scattered proliferative nodules, characterized by foci of exudative epithelioid granulomatous inflammation. The age of the patients, the autoimmune character of the underlying disease, steroid and/or immunosuppressive therapy, and actually the anti-TNF alpha treatment may also have played a role in the exudative character of miliary tuberculosis.

The exudative character - beside proliferative epithelioid granulomas – may be regarded as histological evidence of impaired immune reactivity, suggesting an unfavorable outcome.

References

• Bély M, Apáthy Á: Associated Diseases in Rheumatoid Arthritis – A Retrospective Clinicopathologic Study of 234 Autopsy Patients. Ann Rheum Dis 2005; 64(Suppl. 3): 177

Disclosure of Interest None Declared