Anti-PL7 antisynthetase syndrome under interferon therapy

A 62-year-old woman with a past history of chronic hepatitis C virus infection presented an atypical predominantly painful polymyositis following a flu-like syndrome, persisting despite the withdrawal of PEG-interferon alpha-2b therapy. Clinical assessment, then immunological, electrophysiological and iconographic investigations including myositis antibodies, electromyography, pulmonary functions assessment and thoracic CT-scan found respectively "mechanic hands", arthralgia, presence of antisynthetase anti-PL7 antibody, typical myographic features of hip and shoulder girdles involvement, pulmonary fibrosis and restrictive syndrome features. A deltoid muscle biopsy revealed an unclassified myositis getting closer to anti-J0-1 and connective tissue disease associated myositis featuring: some components of polymyositis, dermatomyositis, and the following peculiar pathological aspects: non-caseous granulomatous infiltrate, endomysial microangiopathy and vascular and sarcolemic deposition of complement membrane attack complex. The diagnosis of interferon induced anti-PL7 antisynthetase syndrome with microangiopathic and granulomatous overlap myositis was retained. A treatment associating intravenous immunoglobulin and moderate tapered oral corticosteroids allowed a complete long-term resolution of myositis and a clear improvement of pulmonary involvement. This case points out the wide range of interferon alpha-associated disorders and call for a precise and detailed immunopathological analysis of myositis, instead of the usual vague classification as idiopathic polymyositis or dermatomyositis about antisynthetase syndrome. (C) 2010 Societe francaise de rhumatologie. Published by Elsevier Masson SAS. All rights reserved.,