Tumour necrosis in chromophobe renal cell carcinoma: clinical data to distinguish aggressive variants.

Aim: To assess correlation between necrosis on imaging and pathology reports and prognostic value of tumour necrosis in chromophobe renal cell carcinoma (CRCC).

Methods: Cases were extracted from a prospective renal cancer registry set up in January 2000 containing 470 patients who had surgery for renal cancer in our institution. We reported the outcome of this series and assessed prognostic significance of clinical and pathologic characteristics. Retrospectively, imaging results and histologic slides of CRCC were analyzed and looked for presence and extent of any tumour necrosis and histologic subtype (eosinophilic versus clear variant). Agreement between necrosis diagnosed by CT-scan and histologic necrosis was given by the kappa coefficient.

Results: Of the 470 patients from the database, 21 (4.5%) had CRCC. Their mean age (+/-SD) was 56.4 +/- 11.4 years (range 34-73). Mean tumour size (+/-SD) was 5.6 +/- 4.2 cm. After a mean follow-up of 22.5 months (range 1-80), 4 patients (19%) developed metastases. Tumour size, Fuhrman nuclear grade and presence of necrosis on imaging and on histology were significant prognostic factors for disease progression of CRCC (P < or = 0.01). The histologic subtype was not a prognostic factor. Necrosis assessed preoperatively by spiral CT-scan agreed well with histologic coagulative necrosis (kappa = 0.88). Necrosis extent on imaging and on pathology was not a prognostic factor for disease progression.

Conclusion: Preoperative detection of tumour necrosis is possible. Tumour necrosis on imaging and on pathology provides a clinically useful information for the clinician to distinguish aggressive variant of CRCC.