Lymph node biopsy is performed to 23yrs old woman. There are peripheral lymhadenopathy (axilar, neck, posterior mediastinum), B symptoms and arthralgias. Rheumatic disease is suspected.  
HISTO: highly atypical large- medium cells forms vague nodules around regular necrotic area spreading to paracortical zone.  
IH of infiltrate: CD3/CD2/CD43(+) 100%, CD5(-) (sic!!!), GranzymB(+)80%; CD20/Bcl 6/Bcl 2/CD15/CD10/EBV LMP1/ALK 1/TdT/CD34 (-); CD4+ and CD8+ populations are the similar and atypical enough. Scattered lymho's are CD56+ or CD57+, some activated large cells are CD30+. Some plasmacytes, eo's and prominent venules in the infiltrate. Ki67 in paracortical area- 50%, but till 90% in the perinecrotic zone.  
PROPOSED DIAGNOSIS:  
Peripheral T lymphoma (T zone) with cytotoxic immunophenotype >>> Kikuchi necrotic lymphadenopathy  
ADD IN: Threpine biopsy: Cellularity is about 70%. M/E ratio is about5-6/1. Architecture is moderatelly diffuse. Immature myeloid (?) cells in the central area with vesiculated nuclei and dmall nucleoli. The large mega's with lobulated nuclei are present (< 10 HPF). Fe deposition and reticulin fibrosis are absent.  
BM IH: There are the single CD34 precursors and CD30+ medium sized cells in BM. CD138 interstitial plasma cells (< 5%), CD20+ small single lympho's and interstitial CD3 small- MEDIUM sized cells with atypical and wrincled nuclei with associated apoptotic bodies. EBV LMP1, CD68, CD4/CD8 are pending.