OBJECTIVE: The purpose of our study was to report the diagnostic yield of 58 consecutive imaging-guided biopsies of solid renal masses.
MATERIALS AND METHODS: We retrospectively reviewed all percutaneous renal biopsies of solid masses performed at our institution over 83 consecutive months from May 1998 to March 2005 through a query of our radiology department procedure database. Fifty-five CT and three sonographic biopsies were performed at our institution during this time. A solid renal mass was documented prior to biopsy by contrast-enhanced CT (n = 48), gadolinium-enhanced MRI (n = 6), or sonography (solid noncystic masses, n = 4). The average maximal mass diameter was 3.1 cm (range, 1.0-11.0 cm). Forty-seven (81 %) of the 58 biopsies were performed immediately before percutaneous ablation. Forty-four (76%) of the biopsies were performed using a coaxial technique with side-cutting automated biopsy needles (16-20 gauge), and 14 (24%) were fine-needle aspirations with a Franseen needle (20 gauge) using a tandem technique. In 19 cases, im-munohistochemistry or histochemistry (Hale colloidal iron stain) was used to establish or confirm the diagnosis. Medical records and radiology and pathology reports were reviewed for all patients.
RESULTS: An adequate sample size was obtained in 55 (95%) of 58 renal masses and led to a definitive diagnosis in 52 (90%) of the 58. Renal cell carcinoma accounted for 36 (69%) of 52 diagnostic biopsies. The diagnosis of a benign lesion was made in 14 (27%) of 52 biopsies. Lymphoma (1/58) and metastatic disease (1/58) accounted for the remaining two diagnostic biopsies. Three biopsy samples obtained inadequate sample volumes, and an additional three samples were thought to have adequate sample volume but were not diagnostic. A single false-negative biopsy result was identified after growth was seen on follow-up imaging and subsequent nephrectomy revealed renal cell carcinoma.
CONCLUSION: Imaging-guided biopsy of a solid enhancing renal mass was diagnostic in 52 (90%) of 58 consecutive biopsies. The diagnosis of a benign lesion was made in 27% of diagnostic biopsies. Because of the advances in biopsy and histology techniques, the role of imaging-guided biopsy should be reconsidered.