Pathological Features of Renal Neoplasms Classified by Size and Symptomatology

Purpose: We examined the relationship between tumor size and pathological findings in a contemporary series of surgical renal lesions and we characterized the relationship of incidental and symptomatic tumors to pathological findings. Materials and Methods: We retrospectively reviewed the records of patients treated surgically for renal lesions suspicious for malignancy between March 2000 and May 2005. Specimens were examined for a gross and microscopic description. Statistical analysis was used to determine the correlation of size and symptomatology. Results: A total of 349 renal masses from 331 patients were identified. Of the 349 renal masses 56 (16.0%) were benign, 289 (82.8%) were renal cell carcinoma and 4 (1.1%) were other malignancies. The percent of malignant tumors increased from 72.1% for those less than 2 cm to 93.7% for those greater than 7 cm (OR 1.39, 95% CI 1.17 to 1.65). Of the 349 renal masses 258 (73.9%) were discovered incidentally and 91 (26.1%) were symptomatic. Mean size of incidental and symptomatic tumors was 3.7 and 6.2 cm, respectively (p <0.001). When comparing T1 incidental and symptomatic tumors, there was no significant difference in the overall frequency of malignancy. When comparing T2 incidental and symptomatic tumors, the groups had similar malignancy rates (90.9% and 100%, respectively, p = 0.16). However, symptomatic lesions showed an increased incidence of high grade malignancy (78.4% vs 40.9%, p = 0.012). Conclusions: Smaller renal tumors are more likely to be benign or be a lower grade of malignancy. T1 renal tumors are more likely to be detected incidentally than T2 tumors. When T1 incidental and symptomatic tumors were compared, there was no difference between the malignancy rates. However, when T2 incidental and symptomatic tumors were compared, symptomatic tumors were more likely to be high grade malignancy.