What is a Myriad pattern Antinuclear Antibody (ANA)?

Myriad Pattern ANA: Understanding and Clinical Significance

The Myriad pattern in Antinuclear Antibody (ANA) testing is not a recognized standard pattern in the international classification of ANA patterns. The term "Myriad" is not described in the international recommendations for the assessment of autoantibodies to cellular antigens referred to as anti-nuclear antibodies 1.

Standard ANA Patterns and Their Significance

ANA testing by indirect immunofluorescence assay (IIFA) on HEp-2 cells reveals several recognized patterns:

• Nuclear patterns:

  • Homogeneous pattern: Associated with antibodies to dsDNA, histones, chromatin/nucleosomes, and HMG proteins. Commonly seen in SLE, drug-induced lupus, and juvenile idiopathic arthritis 1
  • Speckled patterns:
    • Coarse speckled: Associated with U1-SnRNP, U2-6 snRNP (Sm), nuclear matrix antibodies. Seen in MCTD, SLE, Raynaud's, systemic sclerosis 1
    • Fine speckled: Associated with SSA/Ro, SSB/La, Topo-1 antibodies. Common in SLE, Sjögren's syndrome, systemic sclerosis 1, 2
  • Centromere pattern: Associated with CENP-A, B, C, F antibodies. Seen in limited systemic sclerosis and Raynaud's phenomenon 1
  • Nucleolar pattern: Associated with PM/Scl, RNA-polymerase antibodies. Seen in systemic sclerosis, Raynaud's, inflammatory myopathies 1
  • Nuclear dot pattern: Associated with Sp100 and PML bodies, seen in primary biliary cirrhosis and autoimmune hepatitis 3

• Cytoplasmic patterns:

  • Diffuse cytoplasmic pattern: Associated with ribosomal P proteins, Jo-1, and other tRNA synthetases 1

Importance of Standardized Reporting

The International Consensus on ANA Patterns recommends:

• Both pattern and titer should always be reported for ANA results 2
• IIFA on HEp-2 cells remains the reference method for ANA detection 1
• The term "anticellular antibodies" (ACA) has been proposed to replace "antinuclear antibodies" as it better encompasses antibodies directed at various cellular compartments 4

Clinical Approach to ANA Results

• A screening dilution of 1:160 on HEp-2 substrates is generally suitable for detecting clinically significant ANA 2
• Higher titers (>1:160) have greater clinical specificity (86.2%) while maintaining appropriate sensitivity (95.8%) for systemic autoimmune rheumatic diseases 2
• Follow-up testing should be pattern-specific:
  • For homogeneous patterns: Anti-dsDNA testing is recommended 2, 5
  • For speckled patterns: Testing for specific extractable nuclear antigens (ENA) is indicated 2, 6

Common Pitfalls in ANA Interpretation

• ANA testing is primarily intended for diagnostic purposes, not for monitoring disease progression 1
• Up to 25% of sera from apparently healthy individuals can be ANA positive, depending on demographics and test variables 1
• Different laboratories may use different methods and cutoffs, affecting result interpretation 2
• In cases of high clinical suspicion, physicians should request determination of specific antibodies regardless of the ANA result, as some autoantibodies may be present in ANA-negative patients 1, 2

Conclusion

If you have encountered the term "Myriad pattern" in an ANA report, it may be a laboratory-specific designation not recognized in international classification systems. For proper interpretation, it would be advisable to contact the laboratory for clarification on what specific pattern they are describing with this term, as standardized nomenclature is crucial for proper clinical interpretation of ANA results 1.