Comparison of different diagnostic methods for lupus pleuritis and pericarditis: A prospective three-year study

Background and purpose: Pleural or pericardial effusions, or both, are comm only encountered, but the differential diagnosis is sometimes difficult. We evaluated the diagnostic value of effusion immunofluorescent antinuclear a ntibody (ANA) titer, systemic lupus erythematosus (SLE) latex agglutination slide test, and cytologic LE tell examination in patients with pleural and /or pericardial effusions of various etiologies. Methods: A total of 153 pleural and/or pericardial effusion specimens were collected by aspiration from 152 patients (14 SLE and 138 non-SLE patients) . All specimens were sent for routine biochemistry testing, determination o f ANA titer, SLE latex agglutination slide test, and LE cell examination. Results: Ten of the 14 SLE patients had lupus serositis and all of them had high ANA titers (greater than or equal to 1:160) in their effusions. SLE l atex and LE cell tests were positive in seven and eight patients with lupus serositis, respectively. The remaining four SLE patients with effusion of etiologies other than lupus serositis had low or negative effusion ANA. tit ers. Among the non-SLE patients, 29 of 112 patients (26%) with pleural effu sion and six of 26 patients (23%) with pericardial effusion had positive AN A tests (greater than or equal to 1:40). None of them had a positive SLE la tex or LE cell test result. Thirteen of the 138 non-SLE patients (11%) had high effusion ANA titers (greater than or equal to 1:160). Effusion in 11 o f 13 non-SLE patients (85%) was due to malignancy. Conclusions: Effusion ANA titer detection is a very sensitive but nonspecif ic lest for the diagnosis of lupus serositis. SLE latex and cytologic LE ce ll tests can aid in the differential diagnosis as complementary tools. The specificity, positive and negative predictive values of these two tests are excellent for the diagnosis of lupus serositis.