Renal tumors in solid organ recipients: clinical and pathologic features.

OBJECTIVES: Solid organ recipients are several times more likely to develop renal cell carcinoma (RCC) compared with the general population, but little is known about the features of these tumors. The aim of this study is to report on the characteristics of renal tumors in solid organ recipients compared with the general population.
MATERIALS AND METHODS: Patients undergoing surgery for a localized renal mass between 2000 and 2008 were studied. Demographic, clinical, radiographic, and pathologic characteristics were compared between patients with and without a history of organ transplant. A subanalysis focused on the features of a kidney compared with another non-renal organ transplant.
RESULTS: Of 950 patients identified, 19 were organ recipients. Transplant recipients were younger and had lower body mass indices. Most organ recipients (94.7%) were asymptomatic at presentation. Transplant recipients had higher incidence of malignant pathology (88.2% vs. 78.7%), but had smaller masses, of lower stage and grade, and a higher proportion of papillary histology (35.3% vs. 19.8%). Papillary subtype accounted for almost one-half of the RCCs in kidney recipients compared with 20% in other organ recipients. Over a median follow-up of 4 years, 1 (5.9%) local recurrence, no metastatic progressions, and no RCC-related deaths occurred in the transplant cohort.
CONCLUSIONS: Organ recipients typically present with incidental renal masses of smaller size. However, these are twice more likely to be malignant compared with the general population. RCC arising in transplant recipients tend to be of lower stage and grade, contributing to the apparently excellent oncologic outcomes of surgical treatment.