Renal oncocytoma with vascular invasion: a series of 22 cases

Renal oncocytomas are benign neoplasms that are often excised, as clinically they cannot be distinguished with certainty from renal cell carcinoma. One of the least common findings in oncocytomas is vascular invasion, and their behavior is not well characterized with only reports of isolated examples and smaller case series. Whether vascular invasion is acceptable for the diagnosis of oncocytoma still remains controversial, even amongst genitourinary pathologists with expertise in renal tumor pathology. Of 1474 cases of renal oncocytoma identified at 3 large medical centers, 22 (1.5%) had vascular invasion. Patients included 12 men and 10 women with an average age at diagnosis of 67.5 years (range, 48-91 years). Thirteen cases showed large vessel invasion, and the remainder involved medium or small vessels. Tumor was grossly visible in the renal vein in 2 cases. Clinical data were available on 16 of the 22 cases with an average follow-up time of 29.9 months (range, 7.5-94.5 months). Of the cases with clinical follow-up, all but one individual was alive. All living individuals were free of recurrence or metastatic disease at the time of last follow-up. Our cohort showed no metastasis or recurrence and overall survival of 94.7% at 2.5 years following diagnosis, supporting the finding that vascular invasion does not alter the favorable prognosis of oncocytoma. The presence of vascular invasion should not lead to any uncertainty about the diagnosis in an otherwise typical oncocytoma.