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Patients with dermatomyositis, prior corticosteroid use show inflammatory infiltrates on biopsy
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The presence or degree of inflammatory infiltrates found in muscle biopsies of patients with dermatomyositis was not affected by previous use of corticosteroids, according to researchers at the University of São Paulo in São Paulo, Brazil.
A retrospective study of 65 patients with dermatomyositis (DM) was conducted at a single outpatient clinic between January 2000 and January 2014. All patients met Bohan and Peter criteria for DM, and none had neoplasia, other autoimmune diseases, chronic infections, family history of either neuromuscular or muscular diseases, or prior use of statins or fibrates.
Biopsies of the biceps brachii or in the vastus lateralis muscles were collected at the time of diagnosis, along with patient history, demographic data and laboratory tests to confirm diagnosis.
The biopsies were analyzed by the researchers who were blinded to patient data. A third investigator examined the samples in the case of a discrepancy.
After biopsy analysis, patients were categorized by the severity of disease symptoms. Group one showed minimal inflammatory cell infiltrates that were restricted to one interstitial biopsy area. Group two had a moderate appearance of inflammatory cell infiltrates in one or two interstitial biopsy areas, and group three showed moderately present inflammatory cell infiltrates in all interstitial biopsy areas or a significantly higher presence of inflammatory cell infiltrates.
Group three had a higher frequency of necrotic fibers, hyaline, and basophilic and necrotic fibers linked to inflammatory infiltrations, according to the researchers. The basophilic and necrotic fibers were found more frequently in the perimysial and perivascular areas, which were also more likely to have thickened tissues.
Perifascular atrophy was also highest (53.1%) in group three compared with group two (18.8%) or group one (11.8%). No significant demographic characteristics or differences in disease duration were seen in any of the groups, according to the researchers.
More than half of the patients in each group used corticosteroids prior to diagnosis of DM, and the duration of treatment increased with symptom severity. The maximum duration of corticosteroid treatment in group one was 365 days, compared with 575 days in group two and 1,825 days in group three.
The researchers concluded that the use of corticosteroids was not correlated with the severity of inflammation seen in the biopsies. - by Shirley Pulawski
Disclosure: The researchers report no relevant financial disclosures.
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