27
Kidneys, Adrenals, and Retroperitoneum
Fig. 27.16 Histologic section of chromophobe cell renal carcinoma
showing well-defined cell borders with perinuclear clearing and small
irregular hyperchromatic nuclei (H&E x MP).
and hyp erchrom atic sm o oth nuclei w ith a few interspersed cells
w ith p in k granular cytoplasm (see Figs 27.16 and 27.17A).
Genetics
Cytogenetically, th is tu m o r appears distinctive, and karyotyp -
ing reveals te lo m e ric association and a substantial loss o f chro-
m osom es, m ost c o m m o n ly 1, 2, 6, 10, 13, 17, and 21 (Table
2 7.1).83,84 By restrictio n frag m ent p o lym o rp h ism , CCRC also
appears u niq ue fro m RCC, d em onstrating loss o f heterozygosity
fo r 3p, 5q, 17p, and 17q as w e ll as a b no rm a lities o f m ito c h o n -
d rial D N A .84
Im m unohistochem istry
C h rom op h o b e RCC c o m m o n ly express CK-7, ranging fro m 50
to 100% in several studies, w h ic h is very o fte n focal rather than
diffuse. P arvalb um in, a c alcium -b ind ing p rotein th a t is local-
ized to the distal nep h ron e p ith e liu m , is expressed in 100% o f
chrom op hob e RCC. C h rom op h o b e RCCs are also u su ally posi-
tive fo r C -k it (a transm em brane receptor w ith tyrosine kinase
activity in its in tra c e llu la r d o m a in ) in 8 3 -1 0 0 % o f cases and are
negative fo r v im e n tin (Fig. 27.1 7 B -D ). Ksp cadherin, a distal
n ep hron m arker, is also p ositive in m ore th a n 90% o f c hrom o -
phobe RCCs.45
B
Fig. 27.17 Chromophobe cell renal carcinoma. (A) Hale's colloidal iron, blue droplets. (B) Cytokeratin-7 stains membranes positive. (C) CD117 shows
membranous staining and faint cytoplasmic staining. (D) Vimentin is negative (x LP).
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