Résumé :
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Muscle involvement in the setting of anti-threonyl-tRNA synthetase (anti-PL7) syndrome is usually regarded as similar to that associated with anti-Jo1 syndrome and roughly classified as polymyositis or dermatomyositis. Contrasting with this view, we report here a patient with anti-PL7 syndrome-associated muscle involvement, in whom extensive immunopathological evaluation of muscle injuries showed a peculiar pattern. An African 65-yrs HCV-infected woman was treated by peg-interferon (IFN)-alpha-2b (3 ?g/kg/wk) and ribavirin because of increased liver fibrosis at FibroTest. Two weeks after treatment onset, she complained from marked flu-like symptoms and inflammatory arthromyalgias. After 24 wks, treatment was withdrawn but her condition continued worsening. Three months later, she presented with interstitial lung disease, arthralgias, painful proximal muscle weakness, fissured hyperkeratosis and weight loss. CK level was 7xN and CT scan showed interstitial pneumonitis. Muscle biopsy revealed an inflammatory myopathy characterized by (i) active myofiber necrosis process associated with ubiquitous major histocompatibility complex (MHC)-1 expression and membrane attack complex (C5b-9 complement component) deposition on sarcolemma; (ii) scattered endomysial macrophages and CD8+ T-cells; (iii) perivascular inflammatory infiltrates; and (iv) non-caseous granulomatous infiltrate, without giant cell formation. In addition, inflammatory process was associated with endomysial microangiopathy characterized by capillary loss and enlarged vessel lumen. Circulating antinuclear antibodies were positive (1/320), with specificity for threonyl-tRNA-synthetase (anti-PL-7 antibodies). Although clinical presentation was similar to anti-Jo1 syndrome, the histopathological pattern of muscle injuries notably differed. In particular, microangiopathy, sarcolemmal C5b-9 deposition and granuloma were not described in anti-Jo1 syndrome. Generally, we believe that histopathological pattern of muscle involvement associated with myositis-specific antibodies should be in depth reappraised in the light of modern immunopathology. In addition, in our patient, anti-PL7 syndrome developed under IFN-alpha-2b/ribavirin therapy, so pointing out the wide range of IFN-alpha-associated autoimmune disorders
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