Renal cell carcinoma with mixed features of papillary and clear cell cytomorphology: a fluorescent in situ hybridization study

Abstract

We performed fluorescent in situ hybridization (FISH) to investigate the numeric change of chromosomes 7, 17, and Y and loss of chromosome 3p in "papillary renal cell carcinomas (RCC) with extensive clear cell changes (CCC)." Consecutive cases of RCC over a 12-year period were reviewed to identify "papillary RCC with extensive CCC." Immunostaining for cytokeratin 7 and alpha-methylacyl-CoA racemase (AMACR) and FISH for chromosomes 7, 17, Y, and 3p were applied. Of the total of 521 RCC retrieved, there were 49 RCC with papillary architecture and clear cell areas that could be divided into: Group 1 (12 cases), typical clear cell RCC with focal areas of papillary formation; Group 2 (28 cases), focal typical papillary RCC having papillary architecture with extensive CCC; and Group 3 (nine cases), RCC with an admixture of eosinophilic/clear cytoplasm and solid/papillary architecture. Group 1 showed negative immunoreactivity for CK7 and AMACR and absence of numeric chromosomal gain or loss of chromosomes 7/17 and Y. Groups 2 and 3 showed variable reactivity for CK7 and AMACR. Tumors in group 2 and five in group 3 showed trisomies of chromosomes 7 and/or 17 with or without loss of chromosome Y. Loss of small arm 3p was observed in groups 1 and 3 but not in group 2 tumors. In conclusion, papillary RCC may show phenotypical CCC mimicking clear cell RCC. In a small number of cases with mixed histopathological features, FISH is helpful in subtyping RCC.

Clonal trisomies 7,10 and 12, normal 3p and absence of VHL gene mutation in a clear cell tubulopapillary carcinoma of the kidney

“…Some of these tumors are clear cell renal cell carcinomas with focal papillary formations, while other tumors have papillary architecture with extensive (5-100%, median 10%) clear cell change but variable immunoreactivity for cytokeratin 7 and α-methylacyl-CoA racemase. These tumors are in need of further studies [10][11][12].…”

Clear cell papillary renal cell carcinoma: differential diagnosis and extended immunohistochemical profile

“…Areas of cytoplasmic clearing are sometimes present in papillary carcinoma, [11][12][13][14] creating some overlap between these two entities. In particular, 29% of tumors in this study showed a distinctive pattern of branching papillae composed of a main bulbous, rounded core with prominent fibrovascular stroma, giving rise to multiple smaller, 'budding' papillae, in contrast to the typical, more uniform branching pattern of long delicate papillae typical of papillary renal cell carcinoma.…”

Papillary renal cell carcinoma revisited: a comprehensive histomorphologic study with outcome correlations

“…High nuclear grade has also been well described in type 1 P-RCCs in many studies[1,4–6,10,11], in contrast to the low nuclear grade classically described. P-RCCs with optically clear cytoplasm[27] and solid growth pattern[28] have also been described. Furthermore, it has been shown that classic type 1 and type 2 morphologies may be seen in the same tumor[5].…”