Dear dr.Claro, Vade mecum IH site is usefull for sure. We used it for some time too. In this case the infiltrate is too pleomorphic(small lympho's- cleaved cells- immunoblasts), forms strange nodules with fibrous septae (maybe one can see vague nodularity and "clearity" of infiltrate???) and consists of CLEAVED cells. So it's not small lymphocytic with plasma cells like in LPL. CD23 expression is prerequisit of CLL, but the histo picture is far not typical enough. The patient has any lymphocytosis in blood. Low Ki67 index leads us to low grade NHL diagnosis. So marginal zone lymphoma (with focal CD23+) is still most comfortable diagnosis for me. CD43 +/- reaction is not helpfull enough too.

Sorry to have entered the discussion only now. At the moment I have more questions than answers in this case. Nodal marginal zone B-cell lymphomas are rather rare, which implies great caution with this diagnosis. The morphology is not really typical for this entity, the infiltrate seems rather diffuse, no remnants of reactive follicles can be seen in the submitted images. Considerable CD23+, is also not a feature of marginal zone B-cell lymphoma.  
My impression is that the images 4 and 5 show a diffuse infiltrate by predominantly small lymphoid cells, with few interspersed large cells, suggestive of CLL/SLL.  
The fibrous area ( image 3) contaons mainly large cells, beginning transformation? At this stage I tend to support Dr.Claro's suggestion of SLL ( since there seems to be no clinical evidence for CLL). However, for further clarification, I would suggest to add CD5 and Cyclin D1 to the AB panel. Another question: was a bone marrow biopsy performed for staging?  
I will also ask others for their opinion.

I fully accept, that MZL is diagnosis of exclusion, but:  
1. Ki67 20% is too low for transformation?  
2. The nuclear irregularities is too prominent for CLL.  
3. I do not know what represent these spindle- larger cells around sclerotic areas.  
4. CyclinD1 was negative.  
5. It seems, that it is neither LPL nor FL, but SOME NHL with nuclear irreg's and vague nodules and clearity of cytoplasm.  
6. It's difficult to construct the diagnosis on CD23+ only.  
"Low grade B NHL, maybe MZL" diagnosis was formulated with note: CLL cannot be excluded.  
Thank you, Prof.N.Hurwitz.

Following a kind request from Dr. Hurwitz, I am adding my thoughts to the discussion of this very interesting case. I think the best fit in this case is marginal zone B cell lymphoma (MZB), node based, monocytoid variant. Additionally, there is evidence of early transformation to DLBCL (with sclerosis). The morphology e.g. pic.4 is fairly typical: dimorphic appearance of monocytoid/ centrocytoid small B cells with occasional large B cells intermingled. The large B cell component in the sclerotic areas becomes vastly predominant. It resembles a grade 3 FL (are we sure BCL-6 is negative?)  
 
Since EBV infection of B cells can induce CD23 expression I would suggest to perform EBER staining for EBV-RNA. EBV has been associated with Richter transformation of CLL, and has been rarely reported in MZL. I am not saying that this is the case here but, since the expression of CD23 seems to be liimited to the large B cells, the possibility of it should be considered.

Dear dr.A.Orazi, I'm glad to hear from you and in the same time very sad, that the previous KIKUCHI case (the girl is healthy after steroids:)) was lost for 1.5 months. Our postal office guaranties that the letter was sent to US. Please would be so kind to inform us if the case reach you. Sometimes the customs works very well.  
Thank you for supporting opinion of MzL. I'm little bit in doubt with DLBCL version in the evidence of low level of Ki67.  
I can applye EBV LMP1 only by IH in nowadays in this area of the whorld:)  
Thank you for participating.

After another look at images 4 and 5, I agree that there are cells with pale cytoplasma,compatible with monocytoid cells, which does support Ugnius' and Attilios' diagnosis of MZL. Your EBV hypothesis is interesting. Do you have any experience with PTLPDs EBV+ and CD23+?  
Regarding transformation into DLBCL, I am quite positve hat the sclerotic area containig sheeths of large cells does represent an area of transformation. What about the Ki67 index in this area?

Dear Dr. Mickys:  
 
Thank you for your feed back on that challenging case. Glad to know that was KFD after all. Sorry but I did no received anything at all. Unfortunately, things may go wrong with international mail shipping...  
 
Ki-67: I detect some nucleolar staining that make me think the actual number of pos. cells may be higher than that shown in pic. you included. Anyhow I agree with Dr. Hurwitz that focally is DLBCL transformation. If this is still focal, however, may not have a clear clinical implication. Follow up and eventual re-biopsy (to confirm "full borne" DLBCL) maybe reasonable in this case. You can try p53 staining (DO7 Novocastra works well) since this is often positive in the large cells of transformed lymphomas (e.g. Richter in CLL, transformed MALT,SMZCL, blastoid mantle etc). Best regards (to Nina too).  

Dear collegues, thank you for the fruitfull and attractive review. We'll try to provoke the same in the future. Sincerelly yours.

To whom it may concern: there are only single p53+ cells in population. So, I lack enough argues "pro" DLBCL.