Figure 5. Specimens obtained from pleural biopsy. (A) HE staining. High degree of inflammation extending into the adipose tissue of the chest wall is seen. (B) ISH-κ and (C) ISH-λ. There are areas of predominance of κ-positive cells. (D) HE staining. Inflamed areas show atypical cells with enlarged nuclei, which are FO-LBCL cells (red circles in A). (E) HE staining. Inflamed areas of the chest wall have areas with many plasma cells (yellow circled area in A). (F) ISH-κ. FO-LBCL cells are mildly positive for ISH-κ (red circle in B). (G) ISH-κ. An increase in ISH-κ positive plasma cells is observed (yellow circle in B). (H) ISH-λ. FO-LBCL cells are ISH-λ mildly positive in some cells but negative in many cells (red circles in C). (I) ISH-λ. Only a few plasma cells are ISH-λ positive and most cells are negative (yellow circles in C). (A–C: magnification ×20; scale bar: 500 μm, D–I: magnification ×600; scale bar: 20 μm).