5. Eble, J. N. and Bonsib, S. M.: Extensively cystic renal neoplasms:cystic nephroma, cystic partially differentiated nephroblas-toma, multilocular cystic renal cell carcinoma, and cystichamartoma of renal pelvis. Semin Diagn Pathol, 15: 2, 1998

6. Bosniak, M. A.: Re: Surgical management of complex renal cysts:a series of 32 cases. J Urol, 157: 2264, 1997

Reply by Authors. We appreciate the concerns expressedby Bosniak regarding the potential for misinterpretation ofhis widely respected management guidelines to stratify therisk of malignancy in cystic renal lesions. However, thepurpose of our study was to report our experience withlaparoscopic partial nephrectomy for radiologically suspi-cious cystic masses—ours was not a study evaluating thevalidity of the Bosniak criteria. We support, teach and prac-tice the Bosniak classification. Nevertheless, the readershipmust remember that any classification system is essentiallya guideline, and factors such as patient preference, age andco-morbid risk factors always enter into treatment decisionmaking for the individual patient. It is pertinent to indicatethat our results reflect the real-world outcomes of operativeintervention in the setting of the self-selected patient popu-lation seen at a tertiary referral center.

We stand by our data. For this study each CT was spe-cifically re-reviewed by a senior, expert, high volume, aca-demic radiologist well versed in the Bosniak criteria, andblinded to the final histopathological outcomes. Similarly, astaff pathologist, blinded to the CT results, re-reviewed allslides specifically for this study.

Let us address the II and IIF tumors in our study. Onecategory II lesion demonstrated a 1.8 mm area of carcinoma,not necessarily something that would be identifiable on CT.The other category II lesion was a nearly totally necrotictumor with a microscopically identified thin rim of cancer.On CT the lesion was surprisingly homogeneous without

enhancement (figure 1 in article). As such, based on only 9cases, it is unreasonable to conclude that 25% of all categoryII cysts are malignant. Since the study was retrospective, itis not known how many patients with category II and IIFcysts imaged were not operated on during the same period,but the number is certainly many more than 9 (probablycloser to 900!). Curiously, in 1 published study specificallylooking at the Bosniak criteria and interreader variability12.5% of category II cysts were malignant, and that studywas based on only 8 category II cases.1

We disagree with the skepticism expressed by Bosniakabout the impact of a letter to the editor. We believe thatletters to the editor constitute an appropriate and well ac-cepted forum for literary discussion and debate. We areconfident that our finding malignancy in 22% and 25% ofcategory II and IIF renal cysts, respectively, will be placed inthe proper context of the small denominator of highly se-lected, referred patients in our study (9 and 4, respectively).

To summarize, the point of our article is to describe thetechnical nuances of performing laparoscopic partial ne-phrectomy in the setting of a suspicious cystic tumor, whichwe believe represents a higher level of technical challengethan a solid tumor due to the potential for cyst puncture andlocal spillage. This article is not a critique of the Bosniakclassification. We reported our data factually as we encoun-tered it. We are confident that the readership of The Journalis eminently capable of making the appropriate treatmentdecision (watchful waiting vs surgery) when encountering apatient with a suspicious cystic renal mass.

1. Siegel, C. L., McFarland, E. G., Brink, J. A., Fisher, A. J., Hum-phrey, P. and Heiken, J. P.: CT of cystic renal masses: anal-ysis of diagnostic performance and interobserver variation.AJR Am J Roentgenol, 169: 813, 1997

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