Screening of clear cell papillary renal cell carcinoma using tissue microarray technology and its clinical significance

Objective To study a method to screen clear cell papillary renal cell carcinoma (CCPRCC) and the clinicopathological features of CCPRCC. Methods We used tissue microarray technology to screen the CCPRCC from 720 specimens of renal cell carcinoma in the First Affiliated Hospital of Nanjing Medical University from January 2009 to December 2011. The tissue pathology, immunohistochemical phenotype and clinical features of CCPRCC were studied. Results We made a total of 4 tissue microarrays. By immunohistochemical staining cytokeratin 7 (CK7) and alpha-methylacryl-CoA racemase (AMACR/P504S) and combined with previous pathological findings, 8 patients with CCPRCC were screened successfully. Of these patients, 6 were male and 2 were female. The average age was 52.4 years, and the average tumor size was 1.9 cm. Histopathologically, CCPRCC mainly exhibited a mixture of cystic and papillary components, tumor cells with abundant clear cytoplasms and the low Fuhrman nuclear grade. Immunohistochemistry showed strong and diffuse positive for CK7, carbonic anhydrase Ⅸ (CAⅨ) and Vimentin in all cases, moderately positive for vascular endothelial growth factor (VEGF), but negative for AMACR/P504S, CD117 and CD10 (sometimes focally positive). Ki-67 positive cells were less than 5%. CT showed that the tumors were markedly enhanced in corticomedullary phase with heterogeneous enhancement pattern, but no calcification and necrosis. CCPRCC had a favourable prognosis. At a median follow-up period of 68.5 months (range 59-86 months), no cancer-specific death or tumor recurrence was observed in the patients with CCPRCC. Conclusion Tissue microarray provides an effective way to screen CCPRCC. CCPRCC is a rare and low grade malignant tumor, which has the relative specificity of the pathological and imaging features. In the treatment of CCPRCC, the choice of partial nephrectomy may be more suitable for surgery. Key words: Tissue microarray; Clear cell papillary renal cell carcinoma; Clinicopathological features