Sonographically guided renal mass biopsy: indications and efficacy

To review the clinical indications, pathologic results, and success rate of all our sonographically guided solid renal mass biopsies over a 5‐year period. Between 1993 and 1998, 44 consecutive patients underwent sonographically guided percutaneous biopsy of a solid renal mass. Indications included prior history of nonrenal malignancy, metastatic disease of unknown primary origin, previous contralateral nephrectomy for a renal cell neoplasm, a renal transplant mass, suspected renal lymphoma, history of tuberous sclerosis, and poor surgical candidacy. Aspiration biopsies were initially performed with 22‐ to 18‐gauge spinal needles. If the initial cytologic evaluation findings were nondiagnostic, core biopsies were then performed with 20‐ to 18‐gauge core biopsy guns. Dictated sonographic reports of the biopsies were reviewed to determine the following: indication for biopsy, location and size of the renal mass, needle gauge and type, number of needle passes, and complications. Final cytologic and surgical pathologic records were reviewed. Thirty‐six (82%) of the 44 biopsy specimens were diagnostic. Aspirated smears were diagnostic in 24 (67%) of these cases, with the diagnosis made on the basis of cell block alone in an additional 2 (6%). A definitive diagnosis came from core biopsy alone in 10 cases (28%). The 18‐gauge core needle yielded diagnostic results more reliably than the 20‐gauge core needle, and a significant correlation was seen between core biopsy needle size and the rate of diagnostic core samples (P = .017). Pathologic diagnoses included renal cell carcinoma (n = 18), lymphoma (n = 4), oncocytic neoplasm (n = 4), transitional cell carcinoma (n = 2), angiomyolipoma (n = 1), papillary cortical neoplasm (n = 1), and metastatic carcinoma (n = 6). Complications were seen in 4 (9%) of 44 cases; all were treated conservatively. For specific clinical indications, sonographically guided fine‐needle aspiration and core biopsy of a solid renal mass can be performed safely. In many cases, a definitive diagnosis can be made on the basis of fine‐needle aspiration alone. However, diagnosis may ultimately require core biopsy, for which 18‐gauge core needles would be more reliably diagnostic than 20‐gauge needles.