Purpose: We evaluated the effects of different tumor conditions on discrepancy between radiologically measured size and true size of renal tumors.
Materials and Methods: The data from 238 patients who underwent radical or partial nephrectomy for a renal tumor at our institution were reviewed. Radiologic tumor size defined as the largest diameter on a CT scan was compared to pathologic tumor size defined as the largest diameter on gross pathologic examination.
Results: There was no significant difference between the mean radiologic and pathologic size for all tumors (p=0.078). When stratified according to radiologic size range, mean radiologic size was significantly larger than mean pathologic size for tumors <4 cm (p=0.001), but there was no significant difference between them for tumors 4-7 cm, and >7 cm. When classified according to histologic subtype, mean radiologic size was significantly larger than pathologic size only in clear cell renal cell carcinoma (p=0.005). When classified according to tumor location, mean radiologic size was larger than pathologic size in endophytic tumors (p=0.050), but not in exophytic tumors. When endophytic tumors were stratified according to radiologic size range, there was a significant difference between the radiologic and pathologic size for tumors <4 cm (p<0.001) and 4-7 cm (p=0.007), but not for tumors >7 cm.
Conclusions: Radiologic tumor size seems to correlate well with pathologic tumor size. However, there was a tendency to overestimate tumor size in smaller tumors. Endophytic renal tumors are more likely to have size overestimated by CT scan than exophytic tumors.