Problems in the radiologic diagnosis of renal parenchymal tumors.

There has been a great increase in the detection and earlier diagnosis of a host of renal parenchymal tumors because of the continued improvement in imaging studies. Although this change will tend to improve the cure rate of renal cell carcinoma, it also has uncovered many cases that are problematic in both diagnosis and management. It is hoped that performance of high-quality examinations and the experience gained in dealing with these cases have improved our ability to diagnose and manage these problematic cases successfully.

MR imaging in the evaluation of small (< or =3.0 cm) renal masses.

The use of MR imaging in evaluating renal tumors has expanded beyond the established utility for patients with renal insufficiency and allergy to iodinated contrast. MR imaging is increasingly relied on for the evaluation of small renal lesions. The use of gadolinium chelate contrast agents, high performance MR systems, and optimized techniques is essential. This article details our experience using MR to evaluate small renal tumors and reviews the clinical issues pertinent to the management of these lesions.

Angiomyolipoma (hamartoma) of the kidney: a preoperative diagnosis is possible in virtually every case.

The preoperative diagnosis of renal angiomyolipoma should be made in virtually every case because of characteristic clinical and radiologic findings. The clinical, sonographic, computed tomographic, and angiographic findings in 28 patients with this lesion are reviewed. The sonographic findings of increased echogenicity in a renal mass can be helpful in suggesting the diagnosis of renal angiomyolipoma, and the detection of fat in the renal tumor by CT is diagnostic. It is important to make a preoperative diagnosis of this lesion so that the correct treatment approach will be instituted.

The current radiological approach to renal cysts.

The radiologic diagnosis of renal cysts (and their differentiation from renal neoplasms) has come a long way since the 1950s when the approach was surgical exploration, unless clinically contraindicated, for every renal mass detected using urography. Nephrotomography, renal angiography, and cyst puncture have contributed over the ensuing years to the differentiation of cyst from tumor. However, for the most part, sonography and CT (or a combination of these when necessary) have become the main diagnostic techniques for evaluating renal masses, and with their use we have never been more accurate, noninvasive, and relatively economically efficient. The more widespread use of CT has enabled serendipitous discovery of many small renal carcinomas, the removal of which should result in an improvement in the overall cure rate of patients with renal parenchymal neoplasms. On the other hand, we are also discovering many more cysts than we have previously. We must be on guard, therefore, against discovering lesions for which we are unable to establish a radiologic diagnosis of benignity, because this will only increase the need for exploratory surgery once again. It is thus imperative that imaging studies be performed with great care, that diagnoses be based on rigid criteria, and that more experience with difficult lesions be gained so that the proper approach to treatment will be determined. If we are able to accomplish this, then the present radiologic age can be remembered as a time when great advances in the evaluation of renal masses were made, with resultant improved patient management and cure of disease.

Observation of small incidentally detected renal masses.

As more small (< 3.0 cm) incidentally detected renal cell carcinomas are being discovered in elderly patients, a reassessment of the management of these lesions has become an important issue. The use of partial nephrectomy in these small contained renal neoplasms is being more commonly performed, and the use of "watchful waiting" should also be considered as the initial management approach for some of these lesions. This latter approach is based on the experience gained by the observation of the growth rate and behavior of small incidentally detected solid renal masses that have been followed serially over a 2- to 8-year period. This report will review the available data on the growth rate and clinical behavior of small incidentally discovered renal neoplasms, show why a "watchful waiting" approach is reasonable in some of these cases, and outline which patients would benefit from this management approach.

"Faceless kidney": CT sign of renal duplicity.

A CT sign of renal duplicity is described. In kidneys with either bifid renal pelvis or complete duplication of the collecting system, a transverse CT section obtained at the mid pole or junction of the fused upper and lower pole cortical moieties may reveal a "faceless" renal appearance lacking vascular or collecting system elements. Recognition of this finding allows a correct diagnosis of partial or complete duplication of the renal collecting system and prevents a false impression of an intrarenal mass lesion.