Correlation of tumor size and histopathological characteristics for presumed renal cell carcinoma

Abstract

Objective To analyze the incidence of benign lesions in patients undergoing surgery for presumed renal cell carcinoma (RCC) and investigate the correlation of tumor size and histopathological characteristics. Methods From Jan 2003 to Sep 2010,1531 patients (1042 males,489 females with average age of 55.1 years (15 -89 years) underwent nephrectomy.There were 1123 radical nephrectomies and 408 partial nephrectomies for solitary renal cortical neoplasms presumed to be RCC in preoperative imaging study.The pathological tumor size,the percentage of benign lesions and histologic subtypes were analyzed retrospectively.The correlation of Fuhrman grading and tumor size in clear cell type RCC and papillary RCC was investigated as well. Results Pathological examinations revealed that there were 81 (5.3％)benign lesions of 1531 patients.The incidence of benign lesions was 7.8％ in renal masses smaller than 4.0cm,3.8％ in masses with 4.1 - 7.0 cm,and 1.1％ in masses larger than 7.0 cm ( P ＜ 0.01 ).Angiomyolipoma was the most predominant histologic subtype in benign renal lesions with a frequency of 69.5％,52.6％ and 33.3％ in ≤4.0 cm,4.1 - 7.0 cm and ＞ 7.0 cm subgroups,respectively.Oncocytoma was present in 13.6％,15.8％ and 33.3％ of the benign lesions in the above 3 subgroups (P =0.47).One thousand four hundred and fifty cases of malignancies (94.7％) were identified.The frequency of clear cell type RCC was 91.7％ in malignant tumors smaller than 4.0 cm,88.1％ in 4.1 - 7.0 cm malignancies,and 77.6％ in tumors ＞7.0 cm； the frequency of papillary RCC was 4.0％,4.2％ and 7.7％ in the above 3 subgroups,and the frequency of chromophobe cell RCC was 3.6％,5.2％ and 6.3％ accordingly ( P ＜0.01 ).One thousand three hundred and seventeen cases of clear cell type RCC and papillary RCC with definite Fuhrman grading were identified.The probability of high grade tumors increased with size,while the probability of low-grade lesions decreased (r =0.94,P ＜ 0.01 ),especially for tumors smaller than 11.0cm. Conclusions Patients in the present study population show a low incidence of benign renal lesions.Benign lesions are less common in larger tumors than in smaller ones.The proportion of clear cell type RCC decreases in larger tumors,however papillary RCC and chromophobe cell RCC are increasing.The probability of high-grade tumors increases with size.The correlation between tumor size and histopathological characteristics may be helpful in patients counseling and decision-making. Key words: Kidney neoplasms; Benign lesions; Neoplasms by histologic type; Fuhrman grading