CASE IS OPEN FOR DISCUSSION!  
 
41yrs old male with generalized lymphadenopathy and splenomegaly.  
Biopsy core from left suprclavicular LN with repeated excisional biopsy.  
PET-CT: no definite PRIMARY. High active LNs supra and sub-diaphragmatic with conglomeration. SUSPITIOUS nidus in right kidney (tumor spread vs reactive/urine stasis?). Urolgists are sure, that not kidney primary.  
 
FULL IH (core biopsy): PanCK+; Pax8+; p53+ (probably mutated); Vimentin+; TLE1+; BerEp4/EMA(-); CD35+/-; CKHMW/p63/p40/CK5(-); CK7/CK20(-); CAIX/RCC/CD10/Synaptophysin/Chromogranin A(-); TTF1/CDX2/SALL4(-); CD117/CD5/Asm Actin/Desmin/Myogenin/STAT6(-); Ki67 prolif. index up to 30%.  
ALK1 r-jos nėra (0); TFE3(-);  
 
REPEATED IH (excisional biopsy): the same. ADDITIONAL: Fascin +/- faint; EGFR+ (membranous) weak focal;  
 
MOLECS: FOUNDATION ONE:  
FOUNDATION ONE short summary:  
NF2 E204*  
ATR RAB7A-ATR rearrangement  
CDKN2A/B p14ARF rearrangement exon 1  
Microsatellite status - MS-Stable  
Tumor Mutational Burden - 2 Muts/Mb  
UNKNOWN SIGNIFICANCE.  
FLT1 S733del  
RET Y791F  
E-MICROSCOPY: attched picture (low quality).  
 
PROPOSAL 1: Malignant epithelioid tumor, probably fibrous dendritic cell tumor/sarcoma (aka Cytokeratin-positive interstitial cell neoplasm) if any other carcinomas were excluded (kidney? other?).  
PROPOSAL 2: Due to biopsied renal tumor (the same picture and IH, not included): just RCC NOS mts to lymphnode.  
 
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