Fuhrman and modified Fuhrman grading schemes do not apply to chromophobe carcinoma (Delahunt)
Paner et al. have proposed a grading scheme
Grade I
No nuclear crowding and anaplasia (see definitions below)
Grade 2
requires both criteria below:
Nuclear crowding
High geographic nuclear/cytoplasmic density detectable at 10x objective
Some nuclei in direct contact with each other when assessed at 40x objective
Nuclear pleomorphism
Size variation of ≥3-fold and
Distinct nuclear chromatin irregularities
Not smudged nuclear atypia of degenerate foci
Grade 3 requires either
Nuclear polylobation and tumor giant cells, or
Sarcomatoid change
At least two distinct areas required to have above features to determine the grade
Otherwise, use next lower grade
A large study (Przybycin 2011) does not find grading to predict behavior
Following features found to be predictive of adverse outcome
Angiolymphatic invasion
Microscopic necrosis
Tumor size (>7cm)
Sarcomatoid differentiation
Staging
Use TNM staging for all renal carcinomas at present
Remember that it is based predominantly on clear cell carcinomas
It has not been validated as applicable to other types of carcinoma (see Herrmann for an example)
Critical/controversial points in staging of RCC include:
pT3a is defined as extension into perirenal fat
This requires actual infiltration into and between fat cells
It does not include bulging tumor with stretched, thin capsule that appears to touch fat
Classically has been considered fat peripheral to the cortical capsule
It appears that renal sinus (peripelvic) fat should be considered equivalent
The renal sinus must be examined grossly and appropriately sampled
pT3 requires gross involvement of renal vein and or vena cava
This requires an adequate gross examination
Retraction of vascular wall around a lumenal tumor thrombus may falsely suggest a positive margin
Positive vascular margin requires involvement of the vessel wall at the margin
Direct (contiguous) invasion of the adrenal gland (pT4) should be distinguished from discontiguous (metastatic) involvement (pM1)
Bibliography (for Staging)
Murphy WM, Grignon DJ, Perlman EJ. Tumors of the Kidney, Bladder and Related Urinary Structures, Atlas of Tumor Pathology, AFIP Fourth Series, Fascicle 1, 2004
Delahunt B. Advances and controversies in grading and staging of renal cell carcinoma. Mod Pathol. 2009 Jun;22 Suppl 2:S24-36.
Bonsib SM. The renal sinus is the principal invasive pathway: a prospective study of 100 renal cell carcinomas. Am J Surg Pathol. 2004 Dec;28(12):1594-600.
Bonsib SM. Renal veins and venous extension in clear cell renal cell carcinoma. Mod Pathol. 2007 Jan;20(1):44-53.
Bonsib SM. T2 clear cell renal cell carcinoma is a rare entity: a study of 120 clear cell renal cell carcinomas. J Urol. 2005 Oct;174(4 Pt 1):1199-202; discussion 1202.
Herrmann E, Trojan L, Becker F, Wülfing C, Schrader AJ, Barth P, Stöckle M, Hammerschmied CG, Staehler M, Stief C, Haferkamp A, Hohenfellner M, Legal W, Wullich B, Bolenz C, Klein T, Noldus J, Bierer S, Hertle L, Brenner W, Roos F, Michel MS, Walter B, Wieland W, Gerss J, Otto W, Hartmann A. Prognostic factors of papillary renal cell carcinoma: results from a multi-institutional series after pathological review. J Urol. 2010 Feb;183(2):460-6.
