Prevalence and clinical significance of rare antinuclear antibody patterns.

While some of the more frequent antinuclear (auto)antibodies (ANA) patterns such as homogenous nuclear staining have been extensively studied, the prevalence and clinical significance of rare antinuclear antibody patterns are not well understood. For the purpose of this review, we defined rare patterns as patterns occurring in less than 1% of patients that test positive on indirect immunofluorescence. The prevalence of different ANA patterns was determined in 68,128 consecutive patients who attended the outpatient clinic or were hospitalized at the University Hospitals Leuven over a 14-year period (1998-2011). To avoid bias, we only included the first sample for each patient and patients who tested positive in the period 1980-1997 were excluded. There were 9268 patients who tested positive for ANA. With the exception of the clinical association of anti-multiple nuclear dots (at higher titers) and anti-nuclear envelope autoantibodies with autoimmune liver disease, there was no good clinical association of rare ANA patterns with the diagnosis of auto-immune disorders. The most important non-autoimmune cause of rare ANA patterns was carcinoma, particularly in patients with rare cell-cycle related ANAs.