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Biopsy diagnosis of renal tumors. Current applications Ondřej Hes Department of Pathology Charles University and University Hospital Plzeň Czech Republic
Dealing with same tumors BUT in different way
Questions for pathologist Diagnostic material vs non-representative material Primary vs secondary lesion Renal cell tumor vs urothelial origin Subtyping if possible Grading and other prognostic parameters (if possible)
Histologic suptyping: The diagnostic nomenclature recommended for use in renal core biopsies is the WHO 2016 Classification System. Grading: The highest histologic grade observed in a carcinoma should be provided. Due to grade heterogeneity in renal cell carcinoma the recommended diagnostic term should include "at least grade X" Stage- no pt stage recomended by AJCC 2017
There is no generally accepted grading system for chromophobe renal cell carcinoma and rarer subtypes of renal cell carcinoma. However, WHO/ISUP system is usually used to fulfill formal format of our report. In core biopsies adverse prognostic parameters should be reported only if observed (sarcomatoid change, rhabdoid features, necrosis, vascular-lymphatic invasion and tumor infiltrating within adipose tissue).
Immunohistochemistry
AMACR CK 7 CANH 9 Vim
Hypothetic core biopsy IHC: CK 7+, vim +, AMACR weak +
Unusual papillary RCC
Immunohistochemistry Perfect HE (made of good sample) usually provide 2/3 of diagnosis We should carefully consider potential artifacts We should be aware of full spectrum of possible IHC patterns in particular renal tumors (vimentin, CK 7, AMACR, TFE3, etc, etc) Sometimes we have to deal with conflicting IHC pattern In core biopsy- IHC play more important role than in material from standard resection
Molecular genetic testing Mol-gen testing plays an important role in the diagnosis of certain tumor types in renal core biopsies; these include Xp11.2 RCC, t(6:11) RCC, Ewing sarcoma and synovial sarcoma, FH mutation. However- we have limited material (HE, IHC first)!!! Questionable: chromosomal aberration status, VHL, SDH mutation, BHD, ALK rearrangements, etc
Oncocytic lesions MIA Oncocytic cell
Oncocytic cell=pink cell Eosinophilic solid and cystic RCC, Granular variant of CCRCC, SDH def RCC
Oncocytic tumors Oncocytoma Chromophobe RCC Oncocytic PRCC Hybrid (HOCT) RCC=chromophobe RCC according WHO SDH deficient RCC Eosinophilic solid and cystic RCC (sporadic and TS associated) granular clear cell RCC
Renal Oncocytoma
But also.
Immunohistochemical profile CD117 CK 7 patchy +++ (or -) CD117+++ Vimentin (only focally +++) CK 7 vimentin
Chromophobe RCC
and also
Immunohistochemical profile CK 7 CK 7 (diffuse) +++ CD117+++ Vimentin CD56, chrom, syn +++ (extremely rare situation) Vimentin CD117
Renal oncocytoma et al The diagnosis of renal oncocytoma should be made with caution in needle core biopsies. If a definitive diagnosis of renal oncocytoma is made, it requires rigid morphologic criteria combined with supportive immunohistochemical studies. In cases with classic diagnostic features recommend terms are "renal oncocytoma" or "renal oncocytic neoplasm with features consistent of renal oncocytoma". In other circumstances the term renal oncocytic neoplasm may be used with an explanation in the comment explaining which features are unusual for an outright diagnosis of renal oncocytoma.
Take home message Core biopsy from renal mass requires a slightly different diagnostic approach comparing with standard material. Pathologist should work with limited material, which is problematic in renal cell tumors known for their intratumor heterogeneity. All available techniques, like immunohistochemistry and molecular genetic analyses should be used to support morphologic diagnosis, when necessary. Pathologist must carefully decide, which technique is REALLY supportive!!! Never be HERO!
Thank you for your attention Sian-Kaan, Mexico, April 2012