The ANA pattern describes the distribution of fluorescence seen when a patient's serum is tested for anti-nuclear antibodies (ANA) by indirect immunofluorescence on HEp-2 cells. The pattern reflects which specific nuclear or cytoplasmic components are being targeted by the autoantibodies, and different patterns are associated with different autoimmune conditions.

The four main ANA patterns are: homogeneous (diffuse staining of the nucleus, associated with anti-dsDNA and anti-histone antibodies, seen in lupus); speckled (irregular nuclear staining, associated with anti-Sm, anti-Ro, anti-La, and anti-RNP, seen in lupus, Sjögren's, and MCTD); nucleolar (staining of the nucleolus, associated with scleroderma-related antibodies); and centromere (discrete nuclear spots, associated with limited scleroderma and CREST syndrome).