Richard is a General Medicine Advanced Trainee currently in my first year of training, having worked in rural Queensland for the past five years.
Anti-TIF1-γ Antibody Positivity In Dermatomyositis As A Hallmark Of Malignancy Risk: A Case Report
Mr B, a 70 year-old Caucasian man, presented with a two month history of skin rash, painless, progressive muscle weakness and dysphagia to solids. Examination was noteworthy for severe proximal symmetrical limb and bulbar weakness, erythema in a ‘shawl’ distribution, and a heliotrope rash. A diagnosis of dermatomyositis was made following testing with serum creatinine kinase (found to be seven hundred times the upper limit of normal), magnetic resonance imaging of the thigh muscles, and skin and muscle biopsy. An initial standard panel of serum myositis autoantibodies was negative, however, extended testing was positive for antibodies to transcription intermediary factor 1-gamma (TIF1-γ). Whilst initial malignancy screening (including with a computed tomography scan) was negative, detection of anti-TIF1-γ prompted a positron emission tomography (PET) scan. This demonstrated a fludeoxyglucose-avid supraclavicular lymph node, shown on biopsy to be diffuse large B-cell lymphoma.
Dermatomyositis has a well-recognised association with malignancy, with one large population study demonstrating coexisting malignancy in 9.4% of dermatomyositis patients1. Anti-TIF1-γ is a recently-identified autoantibody more strongly associated with malignancy than dermatomyositis alone2. In the largest case series to date of patients with anti-TIF1-γ positive dermatomyositis, 83% had malignancy diagnosed within 18 months3.
Knowledge of the strong association between anti-TIF1-γ antibody positivity and malignancy in dermatomyositis is invaluable in prompting aggressive cancer screening, and thus early detection and treatment of concurrent malignancy.