Individualized renal mass biopsy strategy for Chinese patients with different subtypes and necrosis area

To evaluate the best individualized renal biopsy strategies for Chinese patients with suspected kidney cancer.

From June 2009 to Oct 2010, 100 core biopsy and fine needle aspirations(FNA) have been performed to patients (average age: 62.0 ± 14.2 years) with an indeterminate solid renal mass by computed tomography (CT) scan imaging in-bench. The average tumor size was 4.4 ± 3.5 cm. The core biopsy was performed through a 18 Gauge needle. Frozen sections were obtained intraoperatively in 20 cases. The results were given as malignant, benign, suspect, or nonsignificant. A classification of subtypes of renal cancer might be added by the cytologist. The relationship between enhancing level in CT scan and number of positive biopsy cores rate in renal cancer patients was also analyzed. According to tumor size, two groups were constituted (<4 cm and ≥4 cm). Preoperative subtype and grade were compared with postoperative specimen results.

Among these cellular fine needle aspirations, the specificity for malignancy or benignity was 93%. The proportion of nonsignificant samples was the same in tumors <4 cm (38.4%) as in tumors >4 cm (28.8%) (P = 1.000, Fisher's exact test). Central and peripheral renal tumor biopsies were defined by the 2 pathologists as adequate to obtain a diagnosis in 70%-79% and 79%-84% of the cases respectively. The adequacy of central biopsies increases with decreasing tumor size. Cohen's κ coefficient (CKC) for the concordance on biopsy adequacy was 0.87 (very good) for central biopsies and 0.9 (very good) for peripheral biopsies. All adequate renal tumor biopsies allowed the diagnosis of histologic subtype (HS) for both pathologists. CKC for the concordance on the diagnosis of HS was 0.91 (very good). The concordance between HS on renal tumor biopsy and surgical specimen was perfect in all cases.

According to CT scan information, FNA and core biopsy give useful message accuracy rate. Fine-needle aspiration is complementary to core biopsy, which remains the gold standard of percutaneous sampling. Core renal biopsy can accurately define RCC histologic subtype. However, it does not seem to be able to detect high grade tumors. Tumor size does not seem to influence these results.