PATIENTS WITH RENAL CYSTS ASSOCIATED WITH RENAL-CELL CARCINOMA AND THE CLINICAL IMPLICATIONS OF CYST PUNCTURE - A STUDY OF 223 CASES

Objectives. To clarify the association between renal cysts and renal c ell carcinoma (RCC), we analyzed patient demographics, types of cystic disease, and modes of cyst-tumor coexistence along with the results o f cyst puncture. Methods. A total of 507 hospitals provided informatio n regarding clinical experiences with HCC and cyst puncture over a 2-y ear period. Results. Renal cysts were identified by preoperative imagi ng in 223 (4%) of 5721 patients with RCC. Histologic examination revea led cystic RCC in 56 patients (25%) and RCC associated with cystic dis eases in 167 (75%). Cystic disease included simple cysts in 72 patient s (32%), acquired cystic disease of the kidney (ACDK) in 62 (28%), mul tilocular renal cysts in 20 (9%), polycystic kidney in 3 (1%), and uns pecified or miscellaneous in 10. Cyst puncture performed in 47 (21%) o f 223 patients demonstrated bloody fluid in 20 cases and nonbloody flu id in 27. Cytologic analysis of cystic fluid obtained from 37 patients revealed a malignancy in 5 (14%), accounting for 25% of the bloody an d 4.8% of nonbloody specimens. Cytology failed to detect RCC in ACDK a nd multilocular cysts but was positive in cases of cystic RCC and soli tary cysts. Four of 5 cytology-positive cases comprised those of tumor in cyst and cyst within tumor. Conclusions. Simple cysts and ACDK acc ounted for 60% of the renal cysts associated with RCC. Cystic RCC was involved in 25% of cases. Positive cytology may be expected in select cases, including those with close cyst-tumor relationships and those i nvolving bloody cyst fluid. However, negative cytology does not exclud e RCC.