[Value of percutaneous biopsy for solid renal tumours less than 4 cm in diameter based on a series of 53 cases]

To evaluate the reliability and clinical value of percutaneous biopsy in the diagnosis of small solid renal tumours (less or equal to 4 cm).

Fifty-three patients underwent biopsy for solid renal tumour less than 4 cm in diameter (mean age: 61 years). The mean diameter was 2.57 cm. The mean number of biopsy cores was 1.93. A histological correlation between biopsy and resection specimen was performed on the 32 operated patients.

Biopsy allowed a precise histological diagnosis in 77% of cases: 9/53 benign tumours (17%), 32/53 cancers (60%); 12 biopsies were uninterpretable (normal renal tissue in six cases; necrotic or disrupted tissue in six cases). Management was modified in 13/53 cases (25%): eight benign tumours, three cases of normal renal tissue and two inconclusive cases were followed with no radiological signs of progression. Surgical resection was performed in 32 patients: two tumours were benign; 27 tumours were malignant; three specimens comprised normal renal tissue. For all positive biopsies with a diagnosis of malignant tumour, the Fuhrman grade was correctly evaluated by biopsy in 60% of cases. One false-negative biopsy was observed. For the 41 evaluable biopsies, the sensitivity and specificity were 96 and 100%, respectively.

In this series, biopsy was a reliable examination in this indication with good sensitivity. The absence of cancer on biopsy did not formally exclude neoplasm. If no tumour (benign or malignant) is observed on the examination, a repeat biopsy or surgical resection should be considered.