Study Type – Diagnostic (exploratory cohort)
Level of Evidence 2b
OBJECTIVE
To prospectively determine the accuracy of 14‐, 18‐ and 20‐G core needle biopsies to render the appropriate histological diagnosis of solid, enhancing renal masses, using a controlled, ex‐vivo biopsy technique.
PATIENTS AND METHODS
From March 2007 to September 2007, 31 patients undergoing partial or radical nephrectomy were randomly selected for biopsy. After extirpative surgery, three ex‐vivo biopsies were taken from each lesion with 14‐, 18‐ and 20‐G biopsy needles. One experienced genitourinary pathologist, unaware of patient identifiers and final pathology results, determined the biopsy histology and tumour grade, based on standard haematoxylin and eosin (H&E) techniques and immunohistochemistry.
RESULTS
The final pathological evaluation classified 21 masses (68%) as clear cell renal cell carcinoma (RCC), three (10%) as papillary RCC, three (10%) as chromophobe RCC, three (10%) as oncocytoma and one (3%) as a benign lymphoid infiltrate. The biopsy histology correlated with the final pathology in 29/31 cases (94%) with the 14‐G, 30/31 cases (97%) with the 18‐G and 25/31 cases (81%) with the 20‐G needles. In two cases chromophobe RCC was misdiagnosed with oncocytoma, and vice versa.
CONCLUSION
In this study a minimum of an 18‐G biopsy needle was the most accurate in determining the histological diagnosis. Clear cell and papillary RCCs were accurately diagnosed on biopsy using an 18‐G, whereas oncocytoma and chromophobe RCC were difficult to differentiate using standard H&E techniques and immunohistochemistry.