Objective: Typical signs of papillary renal cell carcinoma (PRCC) are extensive necroses of the tumorous mass, which can modify the clinical appearance of PRCC. These necroses can imitate cysts on radiological examinations (ultrasonography and CT). The tumours are fragile and vulnerable to spontaneous rupture or rupture following minimal trauma (i.e. they act as a locus minoris resistentiae).
Material and methods: A total of 650 patients with a total of 671 renal tumours were surgically treated at our hospital between January 1991 and December 2003.
Results: In 16 cases bilateral tumours were found (in all cases RCC) and in five cases two types of tumour were identified in one kidney [all were a combination of conventional RCC (CRCC) and PRCC]. Altogether, 621 tumours (92.5%) were diagnosed as RCCs. Of these, CRCC was found in 563 cases (90.7%), PRCC in 36 (5.8%), chromophobe RCC in 14 (2.3%) and unclassified RCC in 7 (1.1%). All cases of ruptured PRCC were included in our study. Interestingly, only PRCCs ruptured in this series. Rupture was described in three cases of PRCC (8.3%): it was spontaneous in two cases and resulted from a traffic accident in the third.
Conclusions: The extensive necrosis regularly found in PRCC can cause rupture of the tumour followed by retroperitoneal bleeding. Rupture affected <10% of our cases of PRCC. CT findings are usually not characteristic and can mimic a simple haematoma of unknown origin. Similarly, the perioperative finding is unclear in most cases. The final correct diagnosis of the renal tumour is frequently established only by the pathologist.