Fig. 21. Lymphoma fine-needle aspirate cytology. A. A semicohesive group of large cells with irregular nuclei and sparse cytoplasm. Red blood cells also are present (Diff Quick, × 40). B. A more dispersed group of abnormal lymphoid cells (Diff Quick, × 40). C. A high nuclear-cytoplasmic ratio, hyperchromatic and irregular nuclei, and multiple nucleoli are visible on higher power (Diff Quick, × 60). D. A mitotic figure (Diff Quick, × 60). E. CD20 stain shows the cells to be of B-cell lineage (immunoperoxidase, × 20). F. CD68 immunophenotyping demonstrates the presence of scattered large foamy macrophages within the abnormal lymphoid population (immunoperoxidase, × 20).