title: Dermatomyositis, lobar panniculitis and inflammatory myopathy with abundant macrophages.
abstract: Dermatomyositis (DM) is a rare treatable muscle disorder with a reported favorable outcome in most patients. A localized skin/muscle involvement in a DM patient raises questions of definition and causes such as lymphoma, or relapse. We describe here a young treated DM patient who presented a focal biopsy-proven destructive myositis and dermatitis restricted to the left thigh 15 months after the onset of a treated dermatomyositis. There was evidence of subcutaneous lobular panniculitis, somewhat resembling cytophagic histocytic panniculitis associated with a focal inflammatory myopathy with abundant macrophages that destroyed the sartorius muscle. Mild signs of hemophagocytosis and T-CD3 lymphocytosis were present in the bone marrow, but no monoclonal T-lymphocyte expansion was observed, as searched by autoradiography of the totality of TcR Vgamma families. The patient improved with prednisone and azathioprine. We conclude that this focal complication suggests a continuum between dermatomyositis, CHP, and IMAM, the three syndromes where T-cell activation plays an important role.
authors.affiliation: Neurology Service, Lausanne University Hospital CHUV, Lausanne, Switzerland.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Carrera
authors.forename: Johannes-Alexander
authors.initials: JA
authors.lastname: Lobrinus
authors.forename: Olivier
authors.initials: O
authors.lastname: Spertini
authors.forename: Romain K
authors.initials: RK
authors.lastname: Gherardi
authors.forename: Thierry
authors.initials: T
authors.lastname: Kuntzer
mesh_terms: D000328:Adult; D001706:Biopsy; D003882:Dermatomyositis / Q000276:immunology / Q000473:pathology*; D006801:Humans; D008264:Macrophages / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D018482:Muscle, Skeletal / Q000473:pathology; D009220:Myositis / Q000276:immunology / Q000473:pathology*; D015434:Panniculitis / Q000276:immunology / Q000473:pathology*