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The prevalence of antinuclear antibodies (ANA) in relapsing polychondritis (RP) has been recently reported by Zeuneret al to be as high as 66%,1usually in a low titre with a speckled pattern. We report here on our experience of ANA testing in patients with RP.
The charts of 180 patients followed up in our institution fulfilling the criteria for RP proposed by Michet et al 2 have been recently retrospectively reviewed, with special focus on dermatological manifestations and their relation with myelodysplasia.3 ,4 This aim led us to exclude 36 patients because the association of RP with potentially confounding diseases,3 such as systemic lupus erythematosus (SLE) present in nine, mixed connective tissue disease (MCTD) in five, rheumatoid arthritis in three, Takayasu arteritis in three, mesenteric panniculitis in three, spondyloarthropathy in two, Crohn’s disease in two, psoriasis in two, or Lichen planus in two. Among the 144 patients remaining, 111 have been tested for ANA by using either Hep-2 cells or liver sections as substrate, or both. Most patients had repeated ANA determinations, including initial testing before onset of corticosteroid treatment, and the higher titres were considered for analysis. Figure 1 shows the histogram of ANA positivity according to ANA titre.
ANA were either absent or present in low titres in a majority of patients (73% and 18%, respectively). “Significant” titres—that is, titre > 1/100 ANA—were demonstrated in only 10 of 111 patients (9%). The pattern of fluorescence was as follows: homogeneous in five, homogeneous and speckled in two, speckled and nucleolar in one, perinuclear and nucleolar in one, and not provided in one. Among those 10 patients, five had clinical or ophthalmological features, or both, suggestive of an associated Sjögren’s syndrome including two who had antibodies to both SS-A and SS-B, and two others had a myelodysplastic syndrome.4 None of these 10 patients had antibodies to ds-DNA. Using the same methods, ANA > 1/100 were found in 15 of the 36 patients initially excluded (42%). Among the nine with SLE, ANA > 1/100 and antibodies to ds-DNA (by Farr assay or Crithidia fluorescence) were found in eight patients. All five patients with MCTD had ANA > 1/1000 (in a speckled pattern in four), with positive antibodies to RNP and negative tests for ds-DNA. The two remainders had either rheumatoid arthritis, or Lichen planus associated with multinodular goitre; both of them also had features suggestive of sicca syndrome. Therefore, within these 36 patients, strong ANA positivity was mainly restricted to SLE, MCTD or Sjögren’s syndrome, or all three.
Beside the recent article by Zeuner et al,1 the prevalence of ANA has rarely been reported in RP. McAdam et al found positive ANA in four of their 18 patients tested (22%), and noted 3 of 23 (13%) ANA positivity in a literature review.5 Data regarding ANA were not provided in the large series of patients with RP followed up at the Mayo Clinic.2 ,6 The low prevalence of ANA observed in our cases with “pure” RP—that is, RP not associated with another connective tissue disorder except for a possible Sjögren’s syndrome—agrees with the negative results of tests for IgG antinucleosome antibodies recently reported by our group in this condition.7
We conclude that: (a) the prevalence of ANA observed in RP is low and, (b) as suggested by other authors6 ,8 the finding of a significant titre of ANA in a patient with RP strongly suggests the presence of an associated disorder, such as SLE, MCTD, Sjögren’s syndrome or acquired myelodysplasia.