Antitopoisomerase I antibody in patients with systemic lupus erythematosus/sicca syndrome without a concomitant scleroderma: two case reports.

We describe two female patients with classic systemic lupus erythematosus (SLE) and secondary sicca syndrome associated with topoisomerase I (topo-I, Scl-70) antibody, a specific marker for scleroderma (SSc), which is rarely found in other collagen diseases. During the course of the disease, the sera of these two patients were repeatedly found to be positive for topo-I antibody following a positive screening by ANA-EIA. Neither patient had clinical evidence of scleroderma. One patient remains well nearly 4 years from the first positive serological test. The progression to sicca syndrome in that patient occurred 2 years after having tested positive for antitopo-I antibody. Her frozen serum also tested positive for anti-Scl-70 by the Western blot technique. The other patient, however, died after developing renal and cardiopulmonary complications of lupus, including Libman Sachs endocarditis and pulmonary hypertension. Contrary to the previous patient, the onset of sicca syndrome in this case had preceded the expression of positive antitopo-I antibody. The present cases and other similar previously reported ones are therefore unique in the sense of being a serological challenge to the high specificity of antitopo-I to scleroderma. In addition, they may also represent a new subset of SLE with or without sicca syndrome, which is characterised by the absence of features of scleroderma despite the presence of antitopo-I antibody.