The Jo-1 mystery

Abstract A 51-year-old male patient presented with fever, myalgia, and bilateral thigh pain, followed by proximal weakness of limbs. Laboratory features were suggestive of inflammatory polymyositis (PM). He initially responded to steroids, but subsequently, the patient’s clinical condition deteriorated. In the initial investigations, there was no evidence of any malignancy. Over the next 2 months, he had a catastrophic downhill course—progressive pancytopenia, acute abdominal pain, and features of mesenteric panniculitis and he eventually was diagnosed with acute myeloid leukemia (AML). This case underscores the high index of suspicion for underlying malignancy while managing cases of refractory PM and emphasizes the importance of comprehensive diagnostic evaluation and interdisciplinary collaboration in managing patients with complex autoimmune and hematological conditions. Jo-1 antibody, also known as anti-histidyl-tRNA synthetase antibody, is a specific type of autoantibody associated with a group of autoimmune diseases collectively known as idiopathic inflammatory myopathies (IIMs), particularly polymyositis (PM) and dermatomyositis (DM). Here, we present a case report highlighting the rare clinical association between Jo-1-positive PM and hematological malignancy. The presence of Jo-1 antibodies in this context may suggest potential immune dysregulation or paraneoplastic phenomena linking PM and AML. Accurate diagnosis and timely intervention are crucial for managing patients with complex autoimmune and hematological conditions, especially when they present with atypical clinical features and show poor response to treatment.