A Case of Anti-TIF1γ Antibody-Positive Dermatomyositis Associated With Malignancy.

Dermatomyositis (DM) is a rare acquired autoimmune myopathy characterized by proximal muscle weakness, inflammation, and a typical skin rash. It is considered one of the idiopathic inflammatory myopathies (IIM), a group of heterogeneous systemic diseases that include DM, polymyositis, and inclusion body myositis. A significant portion of patients with IIM, particularly adults, can have an association with malignancy, usually preceded by muscle and skin symptoms. We report a case of a 67-year-old man who presented to the accident and emergency department with a six-week history of proximal myopathy in the upper and lower limbs and a skin rash. After a series of investigations, the patient was diagnosed with anti-TIF1γ-positive DM and concurrent lung cancer. DM is a paraneoplastic disorder that should always prompt a search for malignancy. Early detection of anti-TIF1γ autoantibodies can facilitate an early diagnosis of CAD, allowing for prompt therapeutic interventions. Several autoantibodies with different clinical and prognostic significance have been detected in IIM. However, the recently discovered anti-TIF1γ antibodies appear to be strongly associated with malignancy.