[Comments with respect to 2 patients with anti-Jo 1 antibodies].

Anti-Jo 1 antibodies define a subgroup of patients with polymyositis, which are characterized by the presence of extra-muscular involvement as pulmonary fibrosis, although Raynaud's phenomena, arthritis, tenosynovitis, pleuritis and pericarditis may also be present. Given the fact that extra-muscular signs may precede the clinical diagnosis of polymyositis, as in the two cases that we present here, these antibodies may help us to diagnose the disease before the onset of myositis.