27
Kidneys, Adrenals, and Retroperitoneum
Table 27.4 A Cytologic Grading System for Renal Cell Carcinoma“
Grade6
Nucleoli at low magnification
(x 100)
Nucleoli at high magnification
(x 400)
Nuclear size and shape
Cytoplasm
I
-
-
Small, round
Clear
II
-
+
Larger, irregular
Clear, granular
III
+
+
Larger, irregular
Clear, granular
IVe
+
+
Pleomorphic, larger, bizarre forms; multilo-
bation and hyperchromasia, spindle cells
Clear, granular
+, present; -, absent.
“Based on Furhman's nuclear grading system.
bUsing alcohol-fixed smears stained with Papanicolaou stain.
“Worst-differentiated (most high-grade) cells.
Fig. 27.10 Conventional renal cell carcinoma (RCC), clear cell type,
Fuhrman's nuclear grade II. RCC showing abundant vacuolated clear
cytoplasm and small eccentric nuclei with nucleoli seen only at low power.
(A) High magnification. (B, inset) Low magnification. (C) Diff-Quik stain
accentuates bubbly cytoplasm and basement membrane material (arrow) (x MP).
m ay fre q u e n tly have corresponding cell blocks th a t dem onstrate
surp rising ly large, well-preserved tissue fragm ents, diagnostic
o f RCC. In a series o f 124 renal aspirates, the o n ly diagnostic
m aterial available in 9% o f cases was o n the cell blocks prepared
fro m the FNAs.18
Three d istin ct cell types— the clear cell, the g ranular cell,
and the oncocyte— occurring either exclusively o r adm ixed,
can be recognized on FNA. T he clear cells o f RCC have abun-
dant, fragile, fin e ly vacuolated cytoplasm , best appreciated on
the D iff-Q u ik stain (Fig. 27.10C) b u t also appreciated on the
Papanicoloau stain (Figs 27.10A,B and 27.11).73 V arious vacu-
oles have been described,74 inc lu d in g the large "paper p u nc h"
and sm all punctuate varieties, as w e ll as vacuoles o f irreg ular
size and shape, w h ic h im p a rt a lacy o r w eb -like appearance. The
cell borders m ay be w e ll defined b u t are u su a lly ind istinct. Som e
nuclei to ta lly o r p a rtia lly stripped o f cytoplasm m ay lie in a loose
alveolar pattern in a b u b b ly o r vacuolated background. G ranular
cells have e o sin o p h ilic o r cyanop hilic cytoplasm , w h ic h is m od -
erately dense and granular (Fig. 27.12A,B). O ncocytic cells have
extrem ely dense, eosinop hilic, com pact cytoplasm w ith w e ll-
defined cell borders. Rarely, RCC m ay show a diffuse spindled
Fig. 27.11 Conventional renal cell carcinoma, nuclear grade III. Note
larger irregular nuclei and prominent nucleoli and vacuolated cytoplasm
(Papanicolaou x MP).
appearance. W h e th e r these sho uld be considered a high-grade
va ria n t o f RCC (Furhm an's nuclear grade IV ) o r be classified as a
sarcom atoid RCC is controversial.
The cells m ay be single o r arranged loo se ly in fla t sheets,
clusters, o r an alveolar pattern. The sm ear pattern is occasion-
a lly m ixed, show ing cells arranged in clusters o r in sheets w ith
a focal p a p illa ry arrangem ent characterized b y cells arrayed in
p a p illa ry frond s o n w ell-developed fibrovascular cores. Tum ors
w ith a p re d o m in a n tly p a p illa ry architecture com pose a d istinct
subgroup (discussed later). T he nucleocytoplasm ic ra tio is char-
acteristically low , even in the less-differentiated (hig her nuclear
grade) RCCs (discussed later).
C ytologic grading o f RCCs o n FNAs has been infre q ue ntly
used75 and m ay be lim ite d by the scantiness o f the specimen and
by h o w adequately the tu m o r is represented on just a few needle
passes. A recent study at the M D A C C dem onstrated th a t by using
Furhm an's nuclear grade system,65 an extrem ely hig h concordance
between FNAs and subsequent nephrectom y was possible.76
G rading o f the tu m o r is done on alcohol-fixed Papanicolaou-
stained smears and sho uld be based on the least-differentiated
o r m ost high-grade cells. It has been show n th a t m u ltip le grades
823
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