Ultrasound-guided aspiration cytology of renal expansions.

Ultrasound-guided fine needle aspirates from 52 malignant renal tumours and 128 benign expansions taken in 1982-1988 were analyzed retrospectively. There were three suspicious aspirates (class III) suggesting a possibility of malignancy among the cases of benign renal expansions and seven false negative aspirates (C I-II) among the malignancies. The accuracy, sensitivity and specificity of the method for differentiating malignant cases from benign ones were 94.1%, 85.1% and 97.5% respectively. Cytology was correct in 86% of the radiologically equivocal cases and in 63.6% of the small renal neoplasms. Aspiration cytology identifies haemorrhagic cysts and infectious conditions, but is not reliable for the detection of malignancy in a multilocular cyst.