27
Kidneys, Adrenals, and Retroperitoneum
Table 27.6 Differentiating Features in the Diagnosis of Renal Lesions
Problem
Differential diagnoses
Normal kidney, proximal
tubal cells versus RCC
nuclear grade 1
Normal kidney shows
variegated pattern of
proximal and distal
tubules, glomeruli,
collecting ducts
RCC shows large cell clusters
with vacuolated cytoplasm;
normal structures are absent
Histiocytes of XPN versus
RCC or CRCC
Histiocytes are keratin-
negative and are single cells
RCC: see clusters and single
cells; RCC keratin-positive
CRCC: see clusters and
single cells, keratin-positive,
collioidal iron-positive
CRCC versus oncocytic RCC
versus oncocytoma
CRCC: anisonucleosis, Hale's
colloidal iron-positive;
cells with reticulated, clear
cytoplasm and granular
cytoplasm aneuploid/
tetraploid
EM: microvesicles
Oncocytic RCC usually high
nuclear grade, interspersed
with clear cells, colloidal
iron-negative
Oncocytoma has cells with
densely granular cytoplasm,
band 3 protein-positive
carbonic anhydrase-positive,
diploid
Hepatocytes versus onco-
cytic RCC versus oncocytes
Hepatocytes: single cells/flat
sheets, pigment golden
brown/green
Oncocytic RCC may show
clear cells focally, high
nuclear grade, necrosis
Oncocytes show no pig-
ment, have eosinophilic-
granular cytoplasm, low
nuclear grade
EM: abundant mitochondria
RCC versus adrenocortical
cancer
RCC: keratin-positive, vi-
mentin-positive or negative,
steroid secretion negative
Adrenocortical cancer:
keratin-negative (on cell
block)
EM: mitochondria with
tubular/vesicular cristae,
steroid secretion frequent
Papillary RCC versus CDC
versus TCC versus clear cell
RCC
Papillary RCC: low nuclear
grade, bland nuclei, fine
powdery chromatin, foamy
macrophages, psammona
bodies, intracytoplasmic
golden brown pigment
CDC: tubulopapillary, high
nuclear grade; located in
medulla, with or without
desmoplasia, fibroblasts,
EMA-positive, PNA strongly
positive, UEAI strongly posi-
tive, HMWK-positive
TCC: may be high grade,
cells may have "tails,” may
be impossible to distinguish
from CDC, CEA-positive,
HMWK-positive
Clear cell RCC: lacks
intracytoplasmic pigment;
PNA and UEAI weakly
positive; nuclear grade,
usually Furhman's II-III,
LMWK-positive, HMWK
Metastases to kidney versus
CDC, TCC
Metastasis: compare
with primary neoplasm,
sometimes mucin-positive;
may see normal kidney pa
renchymal structures such
as tubules or glomeruli
CDC: distinctive immuno-
cytochemistry profile with
or without desmoplastic
fragments
TCC: can be difficult to
distinguish from metastases;
both may be CEA-positive,
mucin-positive
RCC: CEA-negative, mucin-
negative, RCC has distinc-
tive cytology; look for clear
cells with eccentric nuclei,
prominent nucleoil
CDC, collecting duct carcinoma; CEA, carcinoembryonic antigen; CRCC, chromophobe renal cell carcinoma; EM, electron microscopy; HMWK, high molecular weight
keratin; LMWK, low molecular weight keratin; PNA, peanut aggulutinin (lectin); RCC, renal cell carcinoma; TCC, transitional cell carcinoma; UEAI,
Ulex europaeus
agglutinin I (lectin); XPN, xanthogranulomatous pyelonephritis.
t u m o r s
o f
t h e
r e n a l
p e lv is
T he e p ith elial m a lig n a n t tu m o rs o f the pelvis are TC C o r UC,
w h ic h occurs m ost com m only, fo llo w e d in frequency by SCC,
adenocarcinom a, and u n d iffe ren tia te d carcinom a, the last tw o
occurring o n ly rarely. U C m ay show squam ous o r g land ular
d iffe re n tia tio n o r m ixed squam ous and g land ular d iffe re n tia -
tio n . T he b enign e p ith elial tu m o rs are p a p illo m a and inverted
p a p illo m a . The la tte r occur rarely, and the lik e lih o o d o f pre-
operative diagnosis is low.
T he diagnostic efficacy o f void ed u rin e cytology in tu m o rou s
lesions o f the renal pelvis and ureters has been d isa p p o in tin g ly
low , averaging o n ly 38% o f cases,107 and has been attrib uted
to the presence o f ureteral o r uterop elvic o b struction and the
lim ita tio n s o f c ytom orp h olog y in the diagnosis o f low-grade
u ro th e lia l neoplasms. C ytodiagnostic accuracy is increased in
specimens collected by ureteral catheter and lavage, w ith the
greatest accuracy reported fo r renal pelvic brushings.111 FN A o f
the renal pelvis is indicated w h e n a mass lesion is detected by
radiographic studies and u rin a ry tract cytology find ing s are neg-
ative. The success rate o f FN A o f TC C o f the renal pelvis has been
reported to be 85% .107
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