International Urology and Nephrology 36: 235–237, 2004. © 2004 Kluwer Academic Publishers. Printed in the Netherlands. 235 Renal stone masquerading as an occult renal cell cancer (incidental RCC) M. S. Ansari, Iqbal Singh & N. P. Gupta Department of Urology, All India Institute of Medical Sciences, New Delhi, India Abstract. We report an unusual case of 40-year-old adult man who presented as a case of urolithiasis but was found to be harboring an incidental renal cell adenocarcinoma. He underwent an uneventful radical nephrectomy. The literature regarding incidental renal cancer and it’s association with urolithiasis has been reviewed and discussed. Key words: Incidental renal cancer, Occult cancer, Renal cell carcinoma with urolithiasis Introduction Incidental renal cell cancer (adenocarcinoma) has been uncommonly reported and discussed [1–9]. We describe herein a case of renal stone disease that upon investigation was found to be harboring an occult malignancy. We have reviewed the literature regarding such occult incidentally discovered renal cancers and their association with renal stone disease. Report A 40-year-old man presented with complaints of dull aching left flank pain for several months and inter- mittent low-grade fever for the past 3 months. There were no other urological complaints. Urine analysis revealed microscopic hematuria and oxalate crystals. Urine culture sensitivity detected no growth, urine cytology for malignant cells and AFB was negative. The renal function tests were also within normal limits. X-ray KUB suggested a radiopaque shadow in the left renal area and the IVP revealed a left poorly functioning kidney with a renal stone and a filling defect in the left pelvis. An ultrasonographic evalu- ation also suggested a space-occupying defect in the lower pole of the left kidney and areas of calcifica- tion. In view of these findings an RGP was performed to distinguish between the renal stone or calcification or defect, it also revealed a persistent filling defect in the lower pole of the left kidney. A contrast enhanced computed tomographic scan (CECT) revealed a left renal mass 7 × 7 cms occupying the lower pole with multiple areas of punctate calcification and a renal stone. Based on this a diagnosis of renal stone with inci- dental renal cancer was made. He underwent a left open radical nephrectomy (Figure 1), the histopath- ology was reported as moderately differentiated renal adenocarcinoma. Discussion The association of renal cell cancer or adenocarcinoma (RCC) with urolithiasis has not been closely looked in to as yet. There has been no randomized pro- spective control study reported as yet, on the possible association of renal stone disease and RCC. At least one recent report [1] seems to suggest that a pos- sible association may exist between the spindle and cuboidal variety of RCC and nephrolithiasis, however this chance association still remains to be proven. Inci- dental detection of renal cell cancer (RCC) in associ- ation with renal stone disease has been rarely reported; only 8 odd cases have been published till date [2–9]. Table 1 shows the worldwide reported cases on inci- dental RCC mimicking urolithiasis. The largest report of incidental RCC published is of a series of 5 cases by Devarajan et al. [2]. In the present case too the patient was diagnosed to be a case of chronic renal stone disease. Initial investigations caused a dilemma whether it was a case of renal stone disease or calcification in a space- occupying lesion. Finally a contrast enhanced com- puted tomography scan confirmed the presence of the