Photomicrographs of LPHD and subsequent transformation. Shown are representative H&E stains (A,C,E,G) and CD20 immunohistochemistry (B,D,F,H) from patient 9 (A-D) and patient 1 (E-H). (A) H&E of initial biopsy of patient 9 showing nodular proliferation of lymphocytes. (B) CD20 stain of initial biopsy highlights large nodules of B cells containing scattered large B cells, characteristic of NLPHD. (C) H&E stain of postrituximab biopsy at low power showing sheets of large atypical lymphocytes, diagnostic of DLBCL. (D) CD20 stain from panel C highlights a focal area in which the large CD20⁺ B cells are surrounded by negatively stained T cells. (E) H&E stain of initial biopsy from patient 1 showing LPHD with vague nodularity. (F) Anti-CD20 antibody stain from highlights loose nodular aggregates of B lymphocytes. Scattered large CD20⁺ cells (L&H cells) are present within and outside the B-cell nodules. (G) H&E section of postrituximab transformation to TCR-BCL showing diffuse proliferation of lymphocytes. (H) CD20 stain of DLBCL demonstrates scattered CD20⁺ large cells with loss of nodularity. The large neoplastic cells are set against a background of T cells. Original magnification, × 150 (A,B,C,E,F) and × 600 (D,G,H).