This lymph node , as far as seen in this technically suboptimal material,shows a largely preserved structure , granulomatous and foam cell rich inflammation and sclerosis . I could not see evidence for a tumorous process and would interpret the changes as infectious-- with all precautions since the cytology and structure is not well preserved.

Sometimes such artefacts are improved on immuno slides and you can have much better morphology (this one is suboptimal and thus could be misleading). It could be feasible to start with a minimal protocol: CD3, CD20, CD30, CD68 and Ki67. Either we'll see the tissue composition more clearly, or the material is completely lost. Since histology seems diagnostically important, it may be helpful to try to reprocess the remaining fixed material, if there is any left.

Suboptimal morphology with lots of plasma cells, dendritic cells, vessles and giant cells, foamy cells... a structure that may rsemble parasite egg is seen in Pic8. I would favor infectious etiology and perform PAS, Grocott, Giemsa and Ziehl-Neelsen stains in order to identify/exclude parasites/germes. Is there foreign material in the lymph node (birefringent?)?

I agree with the previous comments. The changes are most probably reactive and not neoplastic. The giant cell on image 19 is of foreign body type. The foam cells seen on image 14 are peculiar, if you cannot perform all the stains suggested by Dr.Tzankov, a PAS stain is definitely indicated. I cannot think of any immunostains to help to solve the problem. How big was the biopsy ? do you have more material ? if yes all material should be embedded and cut, other areas might disclose changes we did not see on the submitted material.  
could you please try to get more clinical data?  
 

angiofollicular lymphoid hyperplasia- Castleman disease ---- could it be the diagnosis of this case? I'll try to get more about the patient clinical history and also I'll add more images. In general I know that this patient is suffering since 7 years ago; several biopsies were done for her in other ceners and every time there was a different diagnosis

Thank you Mona, please try to get a maximum of information and a maximum of material, because it s very difficult to reach a conclusion on the basis of the provided data. You mentioned Castlemann's disease. I am not sure, if the stroma rich variant could be discussed, but i cannot see convincing evidence for this diagnosis. Another option to be raised is an inflammatory pseudotumor, which might also explain the clinical symptoms. Is there any evidence for an EBV infection ?

Difficult to evaluate this case due to suboptimal photos - some are out of focus. There are some features that bring Castleman to my mind but I agree that infection should be at first investigated. It would be interesting to see the previous biopsy.

The images are difficult to evaluate. Overall, there is not much to add to what Dr. Mueller-Hermelink said. We do both GMS and Fite any time foamy histiocytes are present. PSA may or may not be sensitive enough to cover both. I would recommend that previous biopsies be reviewed in the context of the most recent findings. Regarding IHC work up, I always do CD3 and CD20 in benign appearing lymph nodes with complex morphology. However, in this particular LN, I would wait for histochemical stains for microorganisms and if they are positive, I would not order anything else. If they are negative, the panel would have to be tailored by the patient's history and fine morphology, which are not available now.

new images from the marked areas are added

Thanks Mona for the added images. Image 19 contains a surprisingly large number of giant cells of foreignbody type, one of these cells, in the center of the image seems to contain an inclusion. Is it birefringent?  
The added images confirm the working hypothesis suggested by all of us that a reactive or infectious etiology of this lesion is most likely. Is there any history of trauma or invasive diagnostic investigations ? Do you have any possibility to review the previous biopsies?

this is most likely a reacitve (infectious) process. again, special stains for organisms and a close correlation with serology is recommended

I agree with a most likely infectious process, altough in these longstanding cases often the pathologic agent can morphologically not be found. Specific PCR, if available, could help. In immunocompromised patients, Rhodococcus equi amongst many others could be thought of.