Splenic B-cell lymphomas and leukaemias

Figuur: van WHO 4 naar WHO5

Cases classified in WHO-HAEM4R as CLL/SLL with ≥ 15% of prolymphocytes are now classified as prolymphocytic progression of CLL, cases with <15% of prolymphocytes remain CLL/SLL in WHO-HAEM5. Remaining cases are now renamed as “splenic B-cell lymphoma/leukaemia with prominent nucleoli” (SBLPN). This latter entity has absorbed cases formerly classified as hairy cell leukaemia variant (HCLv) and

very rare cases of splenic marginal zone lymphoma with similar morphological features. It should be noted that the distinction between the various entities cannot always be made in the absence of a splenectomy specimen.

These entities can be best discriminated by pathologic examination of the spleen; in the absence of a splenectomy specimen, bone marrow examination shows characteristic features in SDRPL with a predominant intrasinusoidal pattern, while SMZL and SBLPN have a more diverse growth pattern in the bone marrow and HCL shows a typical diffuse pattern with reticulin fibrosis.