Peripheral blood is practically never affected and bone marrow involvement is rather rare in this type of B-cell neoplasms. Whether bone marrow is affected or not, centroblastic variant is the most common variant in diffuse large B-cell lymphoma (DLBCL), not otherwise specified. Centroblasts are medium-sized (red arrow) to large (green arrows) lymphoid cells with oval to round nuclei containing fine chromatin. Usually, there are two to four nuclear membrane-bound nucleoli. The cytoplasm is usually scanty and moderately basophilic; in some cells, vacuolisation can also occur (yellow arrows).
Tumour cells can be different in their morphology. Some of them have the appearance of blasts with fine nuclear chromatin and a high nuclear-cytoplasmic ratio (green arrows); other pathological cells (red arrows) are smaller, with more mature chromatin and hardly visible vesicular nucleoli, but still with a high nuclear-cytoplasmic ratio. In cells with well-defined nucleoli, these nucleoli are located at the periphery of nucleus.
Tumour cells must be distinguished from erythroid precursors. Unlike the proerythroblast (red arrow), the centroblast (green arrow) has a different structure of chromatin, less basophilic cytoplasm and rather light nucleoli, which are located close to the nucleus outline.
Bone marrow involvement can be monomorphic like in this case, where tumour cells mostly have the appearance of centroblasts (more than 90% of tumour cells). In most cases, however, the tumour is polymorphic with an admixture of of centroblasts and immunoblasts (i.e., centroblasts account for less than 90% of tumour cells).
Atlas of Haematological Cytology [online]. 2016 [cit. 2024-3-29]. Available from WWW: http://www.leukemia-cell.org/atlas.
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