B-cell maturation and corresponding lymphoma phenotypes. The stage of maturation is noted under each cell, and the corresponding malignant lymphoma is noted above the cell. The shaded brown region represents the germinal center. The dotted arrow indicates the possible role of a memory B–like cell in multiple myeloma,⁴³  as outlined in the text. ABC indicates activated B cell–like; GCB, germinal center B cell–like; and SLL, small lymphocytic lymphoma.