Non-Nuclear and Rare Nuclear ANA Patterns in Indirect Immunoflourescence Testing and their Clinical Associations

. Objectives: A standardized nomenclature to report Antinuclear antibody(ANA) is given by the International consensus on ANA pattern (ICAP). The cytoplasmic, mitotic and rare nuclear patterns are infrequently reported.The study was done to understand the clinical significance and frequency of these unconventional patterns in our population. Methods: Retrospective one year blinded study of ANA patterns in serum samples. Results: Of the 4730 samples, 4568 were included after deleting 162 repeat samples. ANA positivity was seen in 673 cases (14.7%). Cytoplasmic patterns were found in 184 cases (27.3%) and mitotic pattern in 16 (2.4%) cases. Exclusive cytoplasmic patterns were seen in 100 cases (14.3%) and exclusive mitotic pattern in 14 cases (2.08%). Rare nuclear patterns were seen in 30 cases (4.5%).The most common exclusive cytoplasmic pattern was filamentous(n=39), whereas the common cytoplasmic pattern associated with nuclear pattern (mixed pattern) was cytoplasmic homogeneous (AC-19). The rare nuclear patterns included Topo-I (n=9), nuclear envelope (n=5), multiple (n=6) and few (n=8) nuclear dots. While some of the common cytoplasmic patterns like filamentous and homogeneous were more frequent in AIDs the uncommon patterns showed varied clinical associations. Conclusion: The study demonstrates the clinical significance of reporting exclusive and mixed non nuclear ANA patterns on IIF as many of these have known autoimmune associations.