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[A study of papillary renal cell carcinoma. Clinicopathological, immunohistochemical features and its typing]
Background:
Papillary renal cell carcinomas (PRCCs) are genotypically distinct from nonpapillary renal cell carcinomas.
Methods:
We studied the clinical, pathomorphological, immunohistochemical features in 34 PRCCs and 7 papillary renal adenomas. Immunohistochemical studies were performed using lectins and antibodies against cytokeratins, epithelial membrane antigen and Tamm-Horsfall protein.
Results:
PRCCs were divided into two types based on the features of tumor cells and vascular stalks. Fifteen PRCCs displayed small cuboidal cells with basophilic cytoplasm and thin, short vascular stalks (type 1, micropapillary). Nineteen PRCCs displayed large columnar cells with eosinophilic cytoplasm and edematous or fibrous thick stalks (type 2, macropapillary). Infiltration of foam cells was more common in type 1. Co-existence of papillary renal adenomas was recognized in three cases among type 1, but in only case among type 2. In type 1, a male to female predominance was evident (13:2), and the majority of tumors in type 1 were in lower nuclear grade and lower stage. The 5-year survival rates of patients in type 1 and 2 were 87% and 46%, respectively. Immunohistochemically, 15 (100%) cases in type 1 were diffusely positive for cytokeratin 7 (CK7), 15 (100%) were positive for cytokeratin 19 (Progen 19) and 11 (73%) were positive for dolichos biflorus agglutinin (DBA). In type 2, only 4 (19%) cases focally stained for CK7, 10 (53%) were stained for Progen 19 and only 2 (10%) were positive for DBA. The staining pattern in papillary renal adenoma was similar to that of type 1, all cases were positive for CK7, four of five cases (80%) were positive for Progen 19 and five of seven cases (71%) were positive for DBA.
Conclusion:
The pathomorphologic and immunohistochemical features suggested that it is possible to divide PRCCs into 2 types and that PRCCs in type 1 confer an favorable prognosis. Furthermore, our results supported the possibility of adenoma-carcinoma sequence.