PTPRC and Arthritis: Onset of arthritis before pulmonary manifestation; symmetrical joint swelling and inflammation of the wrists, ankles, and digits, synovitis: neutrophils, CD4+ T cells, macrophages and plasma cells, pannus formation; increased levels of RF, IL‐1, IL‐6, and TNF‐a, patchy mixed inflammation formed by T cells, B220+ B cells, CD11b+ macrophages, and neutrophils in subpleural and peribronchovascular region, collagen deposition, and decline in lung static compliance