Image-guided biopsy in the evaluation of renal mass lesions in contemporary urological practice: indications, adequacy, clinical impact, and limitations of the pathological diagnosis

With increasing sophistication of imaging modalities, many small indeterminate renal masses are detected, posing therapeutic dilemmas. Minimally invasive techniques such as radio frequency ablation (RFA) and cryotherapy are increasingly used in such settings, making it essential to classify renal mass in biopsies. We evaluated indications, adequacy, spectrum, and limitations of pathological diagnoses in 52 (79%) of 66 adequate biopsies that impacted management by having conservative therapy (less than total nephrectomy). Indication for biopsies in this group was exclusively for indeterminate mass. Biopsies were categorized as 52% clear cell renal cell carcinoma (RCC); 11% papillary RCC; 23% oncocytic neoplasms, subdivided as oncocytoma (10), chromophobe RCC (1), and cannot rule out RCC (1); 8% spindle cell neoplasms; 2% round blue cell tumors; and 4% inflammatory. After biopsy, 29% underwent nephron-sparing surgery, 36% underwent RFA, and 35% were followed up with observation only. One (2%) unresolved oncocytic neoplasm proved to be a chromophobe RCC in the total nephrectomy. Of the 19 patients, 15 who underwent RFA after diagnostic biopsy subsequently underwent post-RFA biopsy to assess therapy response. Complete ablation at first attempt was achieved in 12 of 15 patients. In contemporary urological practice, biopsies are increasingly performed for incidentally detected renal mass to influence the clinical management. Most biopsies can be classified into clinically relevant categories; however, caution is advised while interpreting oncocytic neoplasms because sampling and tumor heterogeneity may adversely affect interpretation.