Coexisting TIF1γ-positive Primary Pulmonary Lymphoepithelioma-like Carcinoma and Anti-TIF1γ Antibody-positive Dermatomyositis.

Anti-transcriptional intermediary factor 1γ (anti-TIF1γ) antibody-positive dermatomyositis (DM) is strongly associated with cancer, although the mechanism of action is still unclear. We herein describe the first known case of an 80-year-old woman diagnosed with TIF1γ-positive primary pulmonary lymphoepithelioma-like carcinoma (LELC) coexisting with anti-TIF1γ antibody-positive DM. The diagnosis of LELC can only be made by a surgical lung biopsy, and not by a computed tomography-guided biopsy, because of heavy lymphocytic infiltration. This instructive case reaffirmed the importance of active screening for malignancy in patients with anti-TIF1γ antibody-positive DM. Interestingly, the results also suggested that the strong relationship which exists between anti-TIF1γ antibody-positive DM and cancer is potentially caused by tumor-derived TIF1γ.