80 yrs female with DLBCL of mandibulla, diagnosed in 2005 May.  
REVIEW: Slightly nodular and fibrotic picture with large lobated cells. IH: CD20+; Bcl6+; Mum-/+; CD10(-); Bcl2+/- (faint); CD30+; LCA+; CD21/CD23(-)(FDCs absent);CD15(-); Pax5+.  
In 2008 March 12cm tumor closed to adrenal projection between right kidney, liver, v. cava inferior was biopsied. Pathology diagnosis: Mesenchymal tumor, more probable high grade GIST with IH: CD117(-)(sic!), CD34/AsmActin/Desmin(-), S100-/+.  
HISTO: Low grade spindle cell tumor. Duodenum mucosa/m. propria and pancreatic tissue closed to tumor.  
REVIEW AND EXPANDED IH in 2009 under request of GIST registry as CD117 negative GIST.  
IH SUMMARY: Vimentin+, EMA+, CD68+, CD23+, CD21+, S100-/+, LCA-/+(?), CD3/CD20/CD34/CD117/PanCK/AsmActin/CD31(-), CD1a(-). Ki67 <5%.  
VIRTUAL SLIDE: Aperio.  
 
PROPOSAL: Retroperitoneal (?) folicullar dendritic cell tumor/sarcoma.  
QUEST: Relations of primary bone DLBCL and FDC tumor (single clone? transdifferentiation? coincidence?).  
ADDITIONAL MATERIALS ARE APPENDED AS EXAMPLES OF DIFFERENTIAL DIAGNOSTICS OF GI TRACT SPINDLE CELL AND DENDRITIC CELL LESSIONS ONLY.  
 
Series of these 2 cases are dedicated to Basel hematopathology team. It's pleasure be with you on the web.  
 

tzankov 2009-11-16 12:44	Thank you Ugnius for sharing with us this case, to which I have little to add. Diagnostic criteria of FDC-sarcoma are fulfilled. Considering the question of transdifferentiation, molecular analyses will probably help (IgH sequencing of both primary DLBCL and FDCS, PAX5 expression/silencing analysis). One interesting question would be if the primary had a germinal center phenotype, since such transdifferentiations are more commonly observed in germinal center-associated B-cell malignancies... Would you study, if you can, the expression of PAX5 in the primary?
ugnius 2009-11-16 15:05	Please find DLBCL HE (PM LBCL like). Salivary gland, bone and msucle closed to tumor. I have no exact data about localisation... IH in seconds...
ugnius 2009-11-16 16:08	IH: CD20+; Bcl6+; Mum-/+; CD10(-); Bcl2+/- (faint); CD30+; LCA+. IH slides are blurred/old. CD21/CD23/Pax5 requested additionally.
ugnius 2009-11-16 17:59	B clonality will be tested. Unfortunatelly I have not more high rezolution tests there...
ugnius 2009-11-16 18:17	Please find the similar third (metastatic) case from 2003, consulted finally by dr.Raf Sciott in Leuven as FDC sarcoma CD23/CD21 (these photos were absent in 2003).
ugnius 2009-11-17 19:39	PRIMARY DLBCL: Pax5+; CD21/CD23 (FDCs absent); CD15(-).
ugnius 2009-11-21 16:38	Please find vietual slides attached.
leoncini 2009-12-22 12:39	I would favor adiagnosis of mesenchmal tumor the stain of c
hurwitz 2010-01-03 12:50	Sorry for entering the discussion only now. I support both Ugnius' diagnoses of DLBCL in the mandible, and FDC tumor/sarcoma in the retroperitoneum. I found only one report on the occurrence of DLBCL and FDC tumor in the same patient, the summary of which I am attaching, in this case a clonal EBV genome was demonstrated in the FDC. In our case,the age of the patient, is an indication for investigation of EBV association. attachment: Follicular dendritic cell tumor of the spleen asso... [Hum Pathol. 2008] - PubMed result.webarchive
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