[Clinicopathological study and immunohistochemical expression of CA9 in cystic multilocular renal cell carcinomas]

Abstract

Objective: Multilocular cystic renal cell carcinoma has been considered as a distinct subtype of clear cell renal cell carcinoma according to 2004 WHO classification. CA9 has proven to be a diagnostic and prognostic marker for clear cell renal cell carcinoma, but the study has been limited to solid tumors. The aim of this article was to analyse the clinical features of multilocular cystic renal cell carcinoma with focus on CA9 expression.

Patients and methods: Nine multilocular cystic renal cell carcinomas were found. Their age was from 33 to 74 years old with a median of 54 years. There were five men and four women. The computerized tomography was analyzed. There were three total nephrectomies and six partial nephrectomies. The follow-up ranged from five to 102 months with a median 56 months. Immunohistochemical staining was performed on surgical samples to detect CA9 expression.

Results: There were seven pT1a, one pT1b and one pT2; four grade 1 and five grade 2. The Bosniak classification was: one B2F, six B3 and two B4. In CT examination, all tumors showed a hypodense mass. Seven out of nine showed multiple intern septa, more or less thick and vascularized with an enhancement after injection of contrast. No metastasis or relapse was found during follow-up. Eight out of nine multilocular cystic renal cell carcinomas expressed strongly CA9.

Conclusion: Multilocular cystic renal cell carcinoma was a low malignant tumor with a good prognosis. The diagnostic criteria based on the WHO classification 2004 should be adopted in routine. CA9 could be a new diagnostic marker for this tumor.