27
Kidneys, Adrenals, and Retroperitoneum
Fig. 27.13 Clear cell component is faintly positive for CD10 (A) and coexpresses cytokeratin (B) and vimentin (D). Granular cell component (inset C) shows
strong CD10 component (E) (x MP).
m ost cases occurring fro m the fifth to the seventh decades o f life,
and m ale to fem ale d is trib u tio n was a lm ost equal.77 S urvival fo r
Thoenes' sm all series o f grade II tu m o rs (W H O ) com pared w ith
s im ila rly graded tu m o rs fro m clear cell RCC showed a higher
5-year survival (92% com pared w ith 62% ) in CCRC th an in
RCC.77
B oth oncocytom a and CCRC are th o u g h t to derive fro m the
cells o f the cortical collecting duct system .13,40 In th is respect th ey
d iffe r fro m RCC, w h ic h is derived fro m the p roxim a l tubule.
T he collecting duct system com prises tw o types o f cells, the
p rincip al cells and the intercalated cells, w ith d istin c tly d iffe r-
ent u ltrastructural features. Intercalated cells are characterized
b y the presence o f ab und ant clear vesicles, som e w ith central
invag inations and glycogen-like particles located in the apical
cytoplasm as w e ll as num erous m ic ro v illi located at the apical
surface. The p rincip al cells tend to show darker cytoplasm and in
general possess larger num bers o f m ito c h o n d ria th an the in te r-
calated cells and do n o t display clear vesicles. CCRC is th o u g h t
to be derived fro m the intercalated cells, based o n th e ir d istinc-
tive apical im m u n o s ta in in g p ro file fo r EM A, the presence o f car-
b o nic anhydrase and, in contrast to oncocytom a, the absence o f
a n io n exchange p rotein band 3.13
Grossly, the cut surface o f the tu m o rs differs fro m th a t o f
clear cell RCC, appearing gray-beige. T h e ir size range is between
6 and 12 cm in diam eter. T he y occur in the m id d le o f the renal
parenchym a and m ay involve the renal pelvis87 o r project above
the renal surface.
By h e m a to x y lin and eosin histolog y, CCRC has a d istinc-
tive appearance w ith tw o variants. T he typical o r "lig h t" v a ri-
a nt includes tu m o rs w ith v o lu m in o u s p olyg onal cells and
cytoplasm th a t is fine, "re tic u la r," and transp arent.13 T his v a ri-
a nt has central to s lig h tly eccentric nuclei, w h ic h are u su a lly
m oderate in size, w ith m arked anisonucleosis and clum ped
c h ro m a tin .75 T he cells dem onstrate a w e ll-d efin ed zone o f
cond ensation along the cell boundaries, im p a rtin g a certain
p la n t-lik e rig id ity to th e cells. The less c om m o n "e o s in o p h ilic "
v a ria n t has sm a lle r p olyg onal cells, accentuated cell b o un d a -
ries, and fin e ly g ranular e o sin o p h ilic cytoplasm p red o m in atin g
in th e m a jo rity o f cells; however, a fe w cells m ay sho w lighter,
fin e ly re tic u la r cytoplasm . B oth cell types are u su a lly p ositive
w ith Hale's c o llo id a l iro n stain. By ultrastructure, th is v a ri-
a nt contains m an y large m ito c h o n d ria w ith vesicular in te rn a l
m em branes. Between th e m ito c h o n d ria are located num erous
m icrovesicles.
825
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