Fig. 4

Histopathological features of the TBLB specimen. a Marked lymphocyte infiltration without forming lymphoid follicle is identified in the alveolar septa (hematoxylin and eosin [H&E] staining, magnification ×200. Scale bar = 100 micro m). b Histiocytes with hinged nuclei are aggregated to form non-necrotizing granuloma (arrow heads, H&E, magnification ×400. Scale bar = 50 micro m). c Most of the lung-infiltrated lymphocytes are CD3-positive T cells (left, CD3; right, CD20, both magnification ×40, Scale bar = 500 micro m)