Microvascular tumor invasion: prognostic significance in low-stage renal cell carcinoma.

OBJECTIVES: To evaluate the role of microvascular tumor invasion (MVI) in clinical behavior and prognosis of low-stage renal cell carcinoma. METHODS: We retrospectively reviewed the records of patients who had undergone radical nephrectomy from 1990 to 2004 for clinically confined kidney tumors (Stage T1-T2N0M0) with a minimal follow-up period of 1 year. The pathology slides were reviewed regarding tumor diameter, pathologic tumor stage, histologic cell type, nuclear grade, macroscopic or MVI, perirenal fat invasion, and neoplastic lymph node involvement. RESULTS: A total of 48 patients, 22 men and 26 women (mean +/- SD age 50.73 +/- 13.03 years, range 20-80) were included in the study. The patients were followed up for a mean +/- SD of 37.65 +/- 18.19 months (range 12-60). MVI was encountered in 8 patients (16.7%); 50% developed treatment failure in the form of distant metastases. Of the 40 patients without MVI, only 2 (5%) had treatment failure. MVI had a statistically significant association with sex (P = 0.017) and stage (P = 0.039). On comparing treatment failure with different patient and histologic parameters, a statistically significant association was noted with sex (P = 0.006) and MVI (P = 0.005). The 5-year disease-free survival rate was estimated at 45% and 90% when MVI was and was not present. Only MVI showed an independent statistically significant impact (P = 0.007) on multivariate analysis considering the impact of MVI, stage, grade, cell type, perirenal fat invasion, tumor size, and patient age on disease-free survival. CONCLUSIONS: The results of our study have shown that MVI is an independent and relevant prognostic parameter for clinically low-stage renal cell carcinoma.

Extrarenal retroperitoneal angiomyolipoma.

Angiomyolipoma of the retroperitoneum is extremely rare with only 7 cases reported to date in the literature. Spontaneous hemorrhage and shock is the most common presentation that requires emergency intervention. We report a case of large extrarenal retroperitoneal angiomyolipoma that illustrates a different form of presentation for such a rare tumor mimicking a large locally advanced renal parenchymal tumor. The diagnosis was made by histopathology after performing radical nephrectomy. Although rare, angiomyolipoma of the perinephric fat may have variable presentations and should be considered in the differential diagnosis of large renal tumors particularly in view of possible kidney sparing management.