MUC1 and synovial sarcoma: In this case, laboratory findings revealed elevated serum levels of KL‐6, SP‐D, and autoimmune markers (antinuclear antibody, and anti‐SS antibody types A and B); thus, the differential diagnosis included connective‐tissue diseases, especially SS whose pulmonary manifestation may present as bronchiectasis and cystic change4 and they are the most mimics of lung cavities.5