Yes, the morphology of the lymphoid infiltrate is highly suggestive of infiltrates of a lymphoproliferative disease. The lymphoid nodules are large irregular and extend into the septa between fat cells. The stains with CD20 show only some positive cells,many of the lymphoid cells within the nodules do not react with CD20. We should see the CD3 stain for comparison.If the CD20 negative cells are negative for CD3 as well, one can assume that the expression of CD20 is week. This together with the morphology and the low proliferation rate raise the possibility of infiltrates of a CLL, since CD20 is only weekly expressed in CLL in fact it may be completely negative on immunohistochemistry. In any case we have to know the pb values, as well as some minimal clinical data, does the patient have enlarged lymphnodes, where ?  
hepatosplenomegaly?  
In general I would like to stress that pb values and clinical information are of utter importance for evaluation of bone marrow biopsies.

I agree with dr. Hurwitz. If lymphoid nodules show mixed pattern with predominantly CD3+ cells mixed with various number of CD20+ cells then I would support the reactive lymphocytosis. FC of BM aspirate will be good for evaluation the cell line of lymphocytes and clonality of B-cells.

Session 2: LN data are placed in.

The node shows at low power some nodularity. It might be worthwhile to stain with CD21 and/or CD23 for FDRCs trying to understand whether the nodularity is perhaps due to colonization.  
Node plus bone marrow: I would like to raise the possibility of a nodal marginal zone B cell lymphoma most likely in transformation to a large B cell process with secondary bone marrow involvement (by its low grade component). The nodules in the bone marrow might represent colonization of preexisting follicles. This could be investigated further by FDRC staining (e.g. CD21/CD23) of the bone marrow biopsy.

Thank you dr.A.Orazi. CD21/CD23 are in progress with some Ig's. In this case the strange feeling remains, that these blasts smaller and more "bluish" for DLBCL. An idea of "immunoblastic lymphadenopathy/EBV" was generated at first.

Sometimes in our lab in BM one can see lymphoid populations in follicles CD20-CD3-: I think it's due to technical reasons (decalsifications? etc.?).

New adds: CD138 and strange enough CD23- there is any FDC network but positivity of large cells. The rest of the material on the block is very scant...

Sorry for insisting: we still have no information on PB values and the distribution of the lymphadenopathy.  
I agree with Attilio, the lymphnode shows some vague nodilarity. High power images show sheaths of large cells with many clusters of small lymphoid cells in between. The large cells and many of the smaller cells are CD20+, which is a strong argument for transformation of low grade B-cell lymphoma into DLBCL. Another argument is the low Ki67 rate in the lymphoid nodule in the BM as opposed to the high rate in the LN. For further chatacterisation I would suggest an incubation with CD5 on the BMB and on the LN.  
A comment to the last image, incubation with CD23 (low lower), the strong reaction in the periphery of the node and the week staining in the center are an indication for insufficient fixatgion of the node.

I hope dr. L.Griskevicius will append some clinical comments on the case.  
CD21/CD23 FDC network completelly absent.  
CD5 reaction correspond CD3 (I will apend photos together with CD43 (pending).

Hello!  
Here is the clinical data of the patient.  
 
Anamnesis:  
About 5 weeks ago the patient seeked medical help because of fever, sore throat, enlargement of lymph nodes and rash (reddish, fine, flat). He was first treated in the hospital of infectious diseases, where after the course of antibiotics his state slightly improved, the fever was absent, tonsils seemed to shrink a little bit. But because of the persistent lymphadenopathy the patient was directed to haematology department.  
 
Current complaints:  
Enlargement of tonsils (with some difficulty to speak and breathe), sore throat, enlarged inguinal and neck lymph nodes, feblile temperature, loss of weight (about 10 kilos in 3 weeks).  
 
Clinical view:  
Enlarged tonsils (nearly touching one another), lymph nodes: in the neck 3-4 cm, axilary 1-2 cm, inguinal 3-4 cm in size. Blood pressure, heart, lungs, liver, kidneys seem OK, on CT scan there is just slight splenomegaly (136 mm) and lymphadenopathy mentioned above and multiple enlaged meseterial and paraaortic lymph nodes.  
 
Periferal blood:  
WBC (*10e9/l) - 15.39, NEU (%) - 64.25, LYM (%) - 16.91, MON (%) - 7.24, EOS (%) - 10.7, BAS (%) - 0.9, NEU (*10e9/l) - 9.89, LYM (*10e9/l) - 2.6, MON (*10e9/l) - 1.11, EOS (*10e9/l) - 1.65, BAS (*10e9/l) - 0.14, RBC (*10e12/l) - 4.795, HgB (g/l) - 138, Hct (l/l) - 0.41, MCV (fl) - 85.5, MCH (pg) - 28.77, MCHC (g/l) - 336.5, RDW (%) - 12.92, Plt (x10e9/l) - 459.7, MPV (fl) - 7.06  
 
Blood marrow:  
CD2+77%, CD3+59%, CD4+22%,CD5+71%, CD7+66%, CD8+39%, CD10+<1%, CD11c+35%, CD14+<1%, CD16+10%, CD19+18%, CD20+18%,CD22+21%, CD23+11%, CD25+19%, CD38+61%, CD45+100%, CD56+30%(CD3-CD56+14%), CD57+44%, FMC7+3%, HLA-DR+45%, sIgM+1%, kappa11%, lambda2%. BM lymphocyte population: T lymphocytes (CD3+) 59%, T4(CD4+) 22%,Tc(CD8+) 39%, T4(CD4+):Tc(CD8+)=0,6; B lymphocytes (CD19+) 18%; NK cells (CD16+ CD56+)~14%. B lymphocyte phenotyping: CD45+, CD5+, CD19+, CD20+, CD22+, CD23+, CD25+(blankus), FMC7+, CD11c+ (weak), CD10-.

What I find a bot confusing is the high number of CD57+ cells (44%) -these increase primarily in viral infections. Did you check the EBV/CMV titers?

Add info: The rest of tumor in the block is CD43+.

How significant is the B-cell population: CD19+, CD20+, CD22+, CD5+ and CD23+? Could flow experts coment on this?

On lymph node, a diagnosis of DLBCL was proposed. I presume this diagnosis as certain.  
In bone marrow, we can see an infiltrate with small lymphoid cells (T cells 60 %; B cells 20 %). I don't know what is the part of the lymphoïd infiltrate in bone marrow among global cellularity. B-cells, in bone marrow, are CD5+, CD23+ suggesting a small infiltrate by a lymphocytic lymphoma. The quality of this labelling is of course crucial.  
To demonstrate that these B-cells are a low grade component of the DLBCL observed in the lymph node it will be interesting to also look at the CD5, CD23 phenotype of the B-cells in the lymph node. I don't know if the CD23 shown labelling is obtained from bone marrow or from lymph node ?  
- If large B-cells in the lympho node are CD5 and or CD23 +, an involvement of BM by a low grade component is likely  
- If large B-cells in the lympho-node are CD5 and CD23 - they can have loosen the Ags of the low grade component found in BM.  
Other hypothesis would be also a second lymphoma in BM or if phenotyping is not sure reactive cells.

Thanks Martine for your simple and straight forward thought. An incubation with CD5 on the lymphnode might help. Since the large cells are CD20+ and CD23+, if it could be proven that they are CD5+ as well, this would be a strong argument for high grade transformation of a low grade lymphoma. Of course CD5 expression might be lost in the transformed population.

There is a BM B lymphoid population that has the following immunophenotype: CD5+, CD23+, CD10-, CD20+, FMC7-. The CD19/5+ population has a kappa/lambda light chain restriction of 6:1. I asume that this confirms the clonality of the population with the immunophenotype most closely related to SLL.  
The molecular analysis of the lymphnode confirmed the clonal rearangement of the IgH chain gene.  
The patient has no history of a low grade hematological malignancy and presented with a 3-4 week history of progressive lymphadenopathy, tonsil enlargement and B symptoms. His PB lymphocyte count is < 5x109/l.  
His PB CMV and EBV PCR were negative.  
Taken together, he may have a DLBCL transformation of SLL.  
The patient has been placed on R-CHOP and responded after two curses.

Sorry: "courses".