TY - CHAP M1 - Book, Section TI - Rheumatologic Diseases A1 - Ali, Asra A1 - Bangert, Carolyn A. A2 - Ali, Asra Y1 - 2015 N1 - T2 - McGraw-Hill Education Specialty Board Review Dermatology: A Pictorial Review, 3e AB - Group of systemic autoimmune diseasesScreeningAntinuclear antibody (ANA): performed using indirect immunofluorescence (IF)Varying concentrations of patient serum are incubated with a tissue substrate (usually human epithelial tumor line HEp-2), and any autoantibodies to nuclear antigens present in the serum bind to the substrateA fluoresceinated antibody is added, and the tissue is observed under fluorescent microscopy to check for a specific staining patternResults reported asTiter: level of antinuclear antibodies significant enough to be defined as a positive ANA. The standard definition is the titer exceeding that found in 95% of normal individuals (5% of normal individuals can be ANA-positive, with titers usually ≥1:320 and a speckled or homogeneous pattern)Pattern: corresponds to the presence of a specific antibody. A certain pattern may indicate the presence of various rheumatologic diseasesA positive ANA is seen inSystemic lupus erythematosus (SLE): 99%Systemic sclerosis (SSc) patients: 97%Dermatomyositis (DM) patients: 40 to 80%ANA patterns and their corresponding antibodiesHomogeneous pattern (Fig. 22-1): complete nuclear fluorescence; specific for SLE– Double-stranded DNA (dsDNA) or native DNA: 70% SLE, associated with lupus nephritis– Histone: 50 to 70% SLE; also the antibody found in drug-induced SLE (but not in drug-induced subacute cutaneous lupus erythematosus)Rim pattern: fluorescence at edges of nucleus, anti-DNA, antihistone and antilaminin antibodies: SLE (most specific) but also may be seen in chronic active hepatitisSpeckled pattern (Fig. 22-2):– SS-A/Ro: 30 to 40% SLE; often with subacute cutaneous lupus erythematosus (SCLE), drug-induced SCLE, and neonatal LE; also seen in Sjögren syndrome (SS), DM– SS-B/La: 15% SLE often with SCLE, drug-induced SCLE, neonatal LE– Antiribonucleoprotein (RNP): 30% SLE; associated with mixed connective tissue disease (MCTD)– Anti-Smith (Sm): 20 to 30% SLE; very specificExtractable nuclear antigens (ENAs)Soluble cytoplasmic and nuclear components that are bound by autoantibodiesAntibodies include Ro, La, Sm, RNP, Scl-70, and Jo-1ENA-4 test– Identifies Ro, La, RNP, and Sm– Used to diagnose SLE, MCTD, and SSNucleolar pattern (homogeneous, speckled, or clumpy staining of nucleolus)– RNA polymerase I (RNA pol 1): 4 to 23% SSc– U3-RNP/fibrillarin: SSc– Topoisomerase I (Scl-70): 22 to 40% of SSc, associated with diffuse SSc– PM-Scl: SSc-polymyositis overlapCentromere pattern (antibodies to kinetochore proteins)– Approximately 22 to 36% of SSc patients– Approximately 60 to 90% of limited SSc patients (e.g., CREST syndrome [calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, telangiectasia]) SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/04/19 UR - dermatology.mhmedical.com/content.aspx?aid=1176116927 ER -