Diagnostic Cytology
Undifferentiated carcinoma
H istolog ically, th is extrem ely rare tu m o r resembles sm all-cell
u nd iffe ren tia te d carcinom a o f the lung, being com posed o f
so lid sheets o f sm all oval cells w ith hyp erchrom atic nuclei. FN A
o f th is e n tity is expected to reveal cells w ith cytologic features
s im ila r to those described fo r u n d iffe ren tia te d SCC.
Metastases to the Kidney
Metastases to the kid ney occur ap p roxim ately tw o to three tim es
as fre q ue ntly as in RCC. T he m ost c om m o n p rim a ry sources o f
renal metastases are the breast, lung, intestine, opposite kidney,
and stom ach. M etastatic tu m o rs are often m u ltifo c a l and b ila t-
eral. Knowledge o f the clinical h is to ry and com parison w ith
the p rim a ry tu m o r u su a lly c on firm the diagnosis o f metastases;
however, d istin c tio n fro m p rim a ry RCC o r high-grade TC C m ay
be problem atic.
Lymphoma of the Kidney
L ym p h om a presents as a s o lita ry mass in th e kid ney; however,
m ost lym p h o m a to u s renal masses represent extension fro m
adjacent sites o f disease o r in v o lv e m e n t because o f general-
ized disease. These patients typ ic a lly present w ith a b d om in al
o r fla n k p ain and an intravenous pyelogram suggestive o f
RCC. CT find ing s are inc on siste nt w ith c on ve n tio na l RCC and
dem onstrate unencapsulated in filtra tiv e s o lid masses th a t are
hypovascular o n angiography. R ecog nition o f lym p h o m a by
FN A in c o n ju n c tio n w ith m arker studies th a t c on firm a m o n -
oclon al B-cell p o p u la tio n is h ig h ly successful and avoids the
need fo r nep hrectom y to m ake th e diagnosis. O f five cases
diagnosed at the M D A C C ,113 three w ere large-cell lym p hom as,
one was a sm a ll cleaved cell lym p h o m a , and one a sm a ll n on -
cleaved cell (B u rkitt's) lym p h o m a . T he d iffe re n tia l diagnosis
o n FN A includes m etastatic p o o rly d iffe re n tia te d carcinom a
and W ilm s ' tu m o r. T he presence o f a m o n o to n o u s p o p u la tio n
o f single sm all, interm ed iate, o r large cells w ith inconsp icu-
ous cytoplasm and associated lym p h o g la n d u la r bodies is ty p i-
cal o f lym p h o m a . P ap anicolaou smears m ay be destained and
stained fo r LCA o r kera tin to c on firm lym p h o m a and ru le o u t
carcinom a. W ilm s ' tu m o r is characteristically a m u ltic o m p o -
n en t tu m o r (see C hapter 29).
Primary Sarcoma of the Kidney
P rim a ry sarcomas o f the kid n ey are extrem ely rare in adults.114
The m ost c om m o n type is leiom yosarcom a, fo llo w e d b y M FH ,
hem angiopericytom a, fibrosarcom a, and unclassified sarcomas.
These tu m o rs generally have a p o or prognosis, w ith a m ean sur-
vival tim e o f 23 m o n th s after diagnosis. FN A cytology o f renal
sarcom a reflects the u nd e rlyin g histology. The typical cytologic
features o f these sarcomas are the same as those described fo r
o th e r b od y sites. T he use o f im m u n o c yto c h e m istry such as kera-
tin , v im e n tin , and s m o o th m uscle studies supplem ented by
u ltrastructural studies fu rth e r confirm s the histogenesis o f the
tum or.
D iffe re n tia tio n o f renal sarcomas fro m RCC m ay be d iffic u lt
i f o n ly the sarcom atoid c om p onent o f RCC is aspirated. The
presence o f p ositive staining fo r keratin in the sp indle cells as
w e ll as a recognizable e p ith elial c om p onent favors the diagnosis
o f sarcom atoid RCC.
Pediatric neoplastic tu m o rs w ill be discussed in C hapter 29.
W ith th e im p roved techniques, increased num bers o f b o th
benign and m a lig n a n t adrenal lesions are being discovered
e ith er in c id e n ta lly o r as part o f a w o rku p fo r m etastatic dis-
ease. Pathologic c o n firm a tio n o f an adrenal lesion is o f p rim e
im p ortance because o f the h ig h frequency o f incid ental benign
adrenal nodules in the general p o p ulatio n. In general, FN A is
used: (1) to d eterm ine the o rig in and character o f b o th cystic
and so lid adrenal masses; (2) to assist in preoperative staging in
patients w h o have m a lig n a n t disease, because discovery o f adre-
nal metastases m ay rad ically alter the in itia l therapy fo r certain
p rim a ry tum ors; (3) to id e n tify postsurgical adrenal metastases;
and (4) to investigate fu rth e r a clinical c o n d itio n th a t m ig h t be
related to the adrenals (e.g. an infectious cause o f adrenal in su f-
imaging Techniques
R adiology in c on ju nc tion w ith FN A cytology has an im p o rta n t
ro le in the w o rku p o f patients fo r possible adrenal gland abnor-
m a litie s.115-122
A drenal
iod ine-168-lab eled
cholesterol has been used to lateralize corticosteroid- o r aldos-
terone-producing adenomas. T his technique makes it possible
to id e n tify the cause o f Cushing's syndrom e as hyperplasia,
carcinom a, o r adenom a. For the diagnosis and lo c a liza tio n o f
p heochrom ocytom a, iod ine-168-lab eled m etaiodobenzylgua-
n id in e has been used.121
Grayscale ultrasonog rap hy is h e lp fu l in d eterm in in g w h ethe r
an adrenal mass is cystic o r solid ; however, sm aller tu m o rs can
be missed.
The m ost useful im aging procedure is CT, w h ic h is capable
o f resolving tu m o rs as sm all as 0.5 cm in diam eter.121 O n cross-
sectional CT images, the rig h t adrenal is located lateral to the
rig h t diaphragm atic crus, m edial to the rig h t lob e o f the liver,
and im m e d ia te ly p osterior to the in fe rio r vena cava. T he le ft
adrenal gland is lateral to the le ft diaphragm atic crus and pos-
terolateral to the aorta. The sup erior p o rtio n o f the le ft gland
is p o sterior to the lesser o m ental sac, and in fe rio rly the gland
lies p o sterior to the pancreas, w ith the splenic vessels passing
between th em (Fig. 27.3 8 ).
The perform ance o f FN A o f the adrenal gland requires a
skilled operator, especially i f the lesion is sm all. The procedure
m ay be perform ed w ith the p atient lyin g in either the prone o r
the lateral p o sition ; 18- to 22-gauge fin e needles are used. A tte n -
tio n to correct placem ent o f the needle in the mass w ith CT
verification is essential i f one is to avoid a false-negative diag-
nosis, such as in the case o f sm all m etastatic lesions. S im ilarly,
a false-positive diagnosis o f an adenom a m ay occur i f the aspi-
rating needle obtains n o rm a l adrenal tissue adjacent to a sm all
m alig n an t lesion, because the cytology o f an adenom a m ay be
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