European Urology

Letters to the Editor published online

I read with great interest the article by Drs. Remzi and Marberger in the February 2009 issue of European Urology [1]. I would like to comment on the article because several questions arose after reading it.

First, the authors stated that renal tumor biopsy should be performed in patients with a solid renal mass, as a significant number of small renal tumors are actually benign. The proportion of benign tumors <3 cm in size can be as high as approximately 25% [2]. In contrast, benign tumors also accounted for approximately 8% of all renal tumors ≥3 cm in size [2], and thus a substantial number of large renal tumors also need histologic confirmation to avoid unnecessary surgery. Currently, thermal ablation therapies of renal tumors are commonly used to treat small tumors in patients who are not indicated for surgery. Minimally invasive treatment, however, might also be selected for large renal tumors in patients with serious coexisting morbidities, although such lesions are difficult to ablate completely in one session [3]. Therefore, renal tumor biopsy should be performed to confirm a histologic diagnosis of large renal tumors as well as small ones before ablative therapies.

Second, the authors stated that tumor volume was not a reliable parameter for determining the proper treatment plan because of large measurement error; however, tumor volume can be calculated precisely and easily on a picture archiving and communications system (PACS) workstation. If tumor contour is manually traced on all axial images, the cross-sectional area is automatically calculated, and thus tumor volume is calculated by multiplying the sum of all cross-sectional areas by the section thickness [4].

Last, the authors stated that renal tumor biopsy is recommended to help differentiate benign from malignant tumors during ablative therapies. It can take several hours or days to evaluate biopsy specimens if various cytologic examinations, including smears, cell block sections, and immunocytochemical staining as well as hematoxylin–eosin staining, are required [5]. Therefore, if renal mass biopsy were to be performed on the same day that ablative therapy is initiated, a conclusive diagnosis might not be possible, thus resulting in a delay in carrying out the ablation procedure.

It is hoped that authors’ responses may help readers to understand their article more fully and be useful to those considering a renal mass biopsy.
Conflicts of interest: The author has nothing to disclose.