Figure 4

Bone marrow pathology: (a) Hypercellular bone marrow with erythroid hyperplasia, involvement by large B-cell lymphoma is not readily evident (Patient 2, × 200). (b) Higher magnification reveals subtle interstitial infiltration by atypical lymphoid cells with large vesicular nuclei (black arrow) which are morphologically similar to the early erythroid precursors (white arrow) (Patient 2, × 600, oil). (c and d) CD20 immunoperoxidase staining demonstrates a predominantly intrasinusoidal pattern of marrow infiltration by large B-cell lymphoma in both cases (c, Patient 2, × 400 oil; d, Patient 1, × 300). (e) Factor VIII immunoperoxidase staining highlights distention of bone marrow sinusoids by cells which at higher magnification (inset) are seen to be neoplastic cells with large nuclei and prominent nucleoli (Patient 2, × 200, inset × 500 oil). (f) Immunoperoxidase staining with antibodies to glycophorin 1A confirms the increase in erythroid precursors and illustrates the similarity between the early erythroid precursors and the large lymphoma cells, which are glycophorin 1A negative (Patient 2, × 600, oil).