The presence of cytoplasmic sialyl
glycoproteins is a conspicuous feature in
chromophobe renal cell carcinoma (RCC). We compared the immunohistochemical expression of sialyl
glycoproteins in chromophobe RCC with that in other types of renal
tumors.
Formalin-fixed,
paraffin-embedded tissues of surgically resected renal
tumors (chromophobe RCC, 14 cases [10 cases of classic type and 4 cases of eosinophilic variant];
oncocytoma, 7 cases; and clear cell RCC, 9 cases) and kidneys from immature infants (4 cases) were immunostained with
antibodies against sialyl
glycoproteins (anti-KL-6 and anti-sialyl MUC1
antibodies). Cytoplasmic expression of KL-6 and sialyl MUC1 was distinctive in the chromophobe RCC and
renal oncocytoma cells, and in the intercalated cells in collecting duct epithelia. Apical-surface staining of these sialyl
glycoproteins was predominantly observed in clear RCC, in the epithelia of the distal tubule and collecting duct, and in the neonatal renal proximal tubule, but not in those of the adult renal proximal tubule. The above-mentioned observations provide additional evidence for similar phenotypic profiles of chromophobe RCC and
renal oncocytoma, and the intercalated cells in collecting ducts and the oncofetal expression of sialyl
glycoproteins in clear cell RCC. KL-6 is a potential
tumor marker for renal
tumors.