49 yrs old woman with diagnosis of DLBCL, diagnosed on core biopsy from retroperitoneal l/n. IH phenotype: Bcl2+ 100%, MUM1+ 80%, Bcl6+ 30%, Ki67+ 80%, CD10-.  
BM findings: INTERSTICIAL slightly clustered atypical "centro-immuno-blasts" ~5% with irregular vesiculated and lobulated nuclei in BM with some small T cell background. AT FIRST GLANCE (NASDE): Erythroid hyperplasia and arch abnormalities MDS like. Without knowing about lymphoma staging the subtle changes might be lost (photo IH only).  
 
PROPOSAL: minute spread of DLBCL in BM.  
SPECIAL QUEST: Minimum criteria sufficient for HIGH GRADE lymphoma diagnosis in BM.  
Thank you for continuous help and support.  

Mueller-Hermelink 2008-04-07 20:18	The most frequent misdiagnosis of minimal involvement of BM by DLBCL is erythroid hyperplasia since the small clusters of large B tumorcells are very hard to distinguish from basophilic erythroblasts -at least in the core slides-without IHC.I agree with your diagnosis of minimal involvement of BM by DLBCL. A formal proof would consist in a immune histochemical and molecular comparison of the retroperitoneal tumor with the BM.
ugnius 2008-04-07 20:24	Thank you. Unfortunatelly Bcl6 (-) on the majority of cells. CD10 (???) and (esp nuclear) Mum1 are on the progress. I have had some cases with SINGLE interstitial cells (1 melanoma and 1 DLBCL case): even PCR studies would be off value. Maybe laser-microdissection helps in such situations? Thank you in advance for comments.
ugnius 2008-04-07 20:26	In ordinary staging/diagnostic BM procedures in cases of "clinical suspition of NHL" we always apply CD20(CD79a)/CD3/CD138 battery (somtimes expanded with CD34/TdT/CD117). Is it reasonable to stain ALL threpines by IH for screening?
hurwitz 2008-04-07 21:51	The confirmation of your diagnosis is the easy part. The reply of your question about routine IHC on BM biopsies is more complicated.   BM involvement by single cells in large B-cell lymphoma mainly occurs in immunedefficient pateints and in ALCL, in these cases routine IHC is indicated. However in immunocompetent patients single cell involvement by large B-cell lymphoma is rare. Routine IHC screening should be decided by individual institutions depending on their facilities. Routine screening on all BM biopsies seems a real luxury. Please let's not forget that a through screening on high quality morphology can be also useful for detection of minor involvement, which then can be confirmed by IHC.
diane.c.farhi 2008-04-08 18:33	I agree that this is involvement by large B-cell lymphoma. The slides are beautiful. It would be good in such cases to include an H&E as well, so we can all become more proficient at suspecting and identifying minimal lymphoma on routine H&E. I agree with Nina that routine immunostaining is a luxury, and cases should be handled on an individual basis.
ugnius 2008-04-08 18:43	Thank you. I will append HE with new stains (appologies for that). CD20+ visualisation was more impressive.
ugnius 2008-04-13 14:32	Add stains: Mum1-; CD10-. HE and NASDE photos with some atypical "blasts" are placed in.
hurwitz 2008-04-17 14:32	Final diagnosis:     Bone marrow involvement by DLBCL (diagnosed on retropreitoneal core biopsy)   Active hemopoiesis with complete maturation of all 3 cell lines     Thanks for the case and the discussion.
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