Evaluation of fine-needle aspiration cytology for renal masses.

Objective: To evaluate the accuracy and use of fine-needle aspiration (FNA) cytology for the diagnosis of renal masses because with the improved quality and increasing use of ultrasonography and computed tomography (CT), asymptomatic renal masses, particularly small (< 5 cm) tumours, are being discovered more frequently.
Patients and Methods: Between 1995 and 1997, 49 patients (mean age 67.5 years, range 42-88, 34 men and 14 women) underwent FNA of a solid or complex cystic mass under radiological guidance. All masses were further evaluated and staged by CT. Solid masses were divided according to size (< 5 cm and >/= 5 cm). Patients were followed up to the determination of a final diagnosis on tissue histology, after nephrectomy where possible.
Results: Thirty-six patients had histologically confirmed carcinoma at nephrectomy, and nine had presumed carcinoma (four unfit for surgery, five with advanced malignancy). The remaining four patients had benign diagnoses. FNA produced insufficient sample in eight cases (16%). The sensitivity was 89% for large (>/= 5 cm) solid masses, 64% for small (< 5 cm) solid masses and 50% for complex cysts.
Conclusion: FNA does not contribute to the diagnosis of malignancy in large (> 5 cm) masses, as good radiological imaging is nearly always diagnostic. For smaller (< 5 cm) masses and complex cysts, FNA can occasionally confirm malignancy, but lack of diagnostic yield and low sensitivity means that FNA is unreliable as a diagnostic tool and will rarely help in the routine management of these patients.