The “Hot” Renal Tumor

Abstract

THE SCANNING characteristics of renal tubular adenomas have not previously been reported. It is the purpose of this case report to illustrate the potential value of the renal scan in the diagnosis of this adenoma ; to our knowledge this represents the first case report of a “hot” renal tumor. Interesting angiographic characteristics are also described. Clinical Summary A 35-year-old Negro female was admitted to Memorial Medical Center with a four-day history of gross, painless hematuria. Her past history revealed that she had had a similar episode eighteen years previously, at which time urological evaluation revealed a mild displacement of the calyceal systems in the midportion of the left kidney, and at cystoscopi examination bleeding from the left ureter was observed. This cleared spontaneously within a few days without recurrence of symptoms, and at that time the patient refused a left renal exploration. There was no history of trauma on either occasion, nor was there evidence of an infectious process. On this admission her physical examination was within normal limits, as was all laboratory work including hematologic and urologic studies. Incidentally, the hematuria subsided spontaneously, exactly as it had eighteen years previously. Pertinent radiologic observations included: (a) displacement of the calyces in the left kidney, (b) persistent area of increased uptake over the suspect mass on serial scans, (c) vascular displacement around the mass, and (d) persistent “blush” in the mass. A preoperative diagnosis of a renal tubular adenoma was made, and this was confirmed at surgery. Discussion The specificity of chlormerodrin for renal tubular tissue is of course well documented (1). In the presence of a functioning solid renal tubular adenoma, one would therefore expect, purely on a physiologic basis, increased uptake over the tumor, rather than decreased uptake which would be encountered with any other space-occupying lesion of the kidney. It is our opinion that this increased uptake is diagnostic of and specific for a solid renal tubular adenoma. Since most radiologists are accustomed to looking for areas of decreased uptake on renal scans, it is quite possible that areas of relatively increased uptake have been overlooked in the past. Delayed scanning should be performed when a renal mass is encountered that does not show a definite reduction in the uptake of isotope. The renal arteriogram in this patient does not show the presence of abnormal vessels. There is definite stretching and displacement of vessels around the tumor mass and a persistent “blush” for at least ten and a half seconds. The angiographic appearance of malignant neoplasms of the kidney is well known and does not resemble the findings in this case (2, 3). Cysts, benign vascular tumors, and other benign neoplasms, such as angiomyolipoma (4), likewise do not present the angiographic findings seen in this case.