Background Incomplete systemic lupus erythematosus (iSLE) is a condition of patients with clinical and immunological signs of lupus who do not fulfill classification criteria for SLE.

Methods iSLE(n=58) was defined by rheumatologists as clinical diagnosis, not fulfilling ACR or SLICCcriteria and had no classification or specific symptoms of other rheumatic diseases. The majority of the iSLE patients were female (98%), aged 38[27–48]years.

Results The median age of iSLE diagnosis was 34[25–43]years. Positive family history of autoimmune rheumatic disease was in 9% of iSLEpts. In the most patients, there were no connection with any provoking factors-57%, in 16%pts the iSLE onset was associated with pregnancy, 7% each-with infection and combined oral contraceptives use, 5%-with insolation. The median disease duration was 13[2–42]months, 12(21%)pts had a disease duration of ≥5 years.

At the onset of iSLE diagnosis, the most patients had clinical and immunological signs-76%, clinical only-15%, immunological only-9%pts. The clinical manifestations were as follows: fever-29%, acute cutaneous lupus-21%, subacute-7%, discoid-2%, panniculitis-3%, non-scarring alopecia-10%, Raynaud phenomenon-5%, oral ulcers-9%, joint involvement-55%, serositis-9%, nephritis-10%, psychosis-5%, migraine-17%, leukopenia-21%, thrombocytopenia-14%, autoimmune hemolysis-7%. Autoantibody profiles revealed the presence of ANA in 83%cases, anti-dsDNA – in 47%, anti-Sm – none, antiphospholipid antibodies(aPL)-in 36% of patients. Eighteen patients (31%) exhibited low complement.

Evolution of iSLE to SLE occurred in 15(26%) of these patients, 2(3%)-to antiphospholipid syndrome, 2(3%)-to osteoarthritis, 1(2%)-to Sjögren’s syndrome, 9(16%)-to none-rheumatic diseases, with a median interval of 19[8–48]months between iSLE onset and the other definite diagnosis. Twenty six patients(45%) continue to be observed by a rheumatologist with a diagnosis of iSLE.

Conclusions The most commonly clinical features in patients with iSLE are joint involvement(55%), fever(29%), hematological manifestations(28%) and cutaneous lupus(24%); among immunological disorders are positive ANA and anti-dsDNA, more than a third of iSLE patients had aPL and hypocomplementemia. Only quarter of iSLEpts were diagnosed with definite SLE within 19months.