Prognostic implications of the magnetic resonance imaging appearance in papillary renal cell carcinoma.

Abstract

To evaluate the prognostic implications of the MRI appearance and pathological features of papillary renal cell carcinoma (pRCC). A total of 128 pRCC in 115 patients who underwent preoperative MRI were characterised in terms of pathological type (type 1 vs. type 2), MRI appearance (focal vs. infiltrative) and additional MRI features. Patients were classified on the basis of the presence or absence of metastatic disease. There were 65 focal type 1, 54 focal type 2 and 9 infiltrative pRCC. All infiltrative pRCC were of histopathological type 2. Renal vein thrombus was present in 89 % of infiltrative pRCC and no cases of focal pRCC. Metastatic disease was observed in 3.7 % of focal type 1, 7.5 % of focal type 2 and 75.0 % of infiltrative type 2 pRCC. Infiltrative MRI appearance was a significant predictor of metastatic disease, independent of pathological type, size and T stage (P ≤ 0.020). Among focal pRCC on MRI, pathological type 2 was not a significant predictor of metastatic disease (P = 0.648). No combination of features achieved significantly greater accuracy for predicting metastatic disease than renal vein thrombus alone (P > 0.5). Infiltrative MRI appearance and renal vein thrombus identify a subset of pathological type 2 pRCC at a significantly increased risk of metastatic disease.