Renal biopsies in the adult

Renal biopsies have always been a bit controversial and in the adult patient, have rarely been required in the presence of an enhancing renal mass, which is always assumed to be a renal cell carcinoma, unless proved otherwise. The only time we have gone ahead with biopsies, has been when there is a high possibility of infection, especially in younger individuals.

A new article by Silverman SG et al in the July issue of Radiology talks about this issue in detail. It divides the indications for renal biopsy into established and emerging.

Established

1. When there is an extra-renal primary and a renal mass
2. When the mass seems non-operable
3. When there are significant co-morbid conditions preventing surgery (Fig. 3)
4. When there is a high risk of infection

Emerging

1. Small lesions less than or equal to 3cms, homogeneous and hyperattenuating. The chance that such lesions may be benign increases with reducing size, being almost 44% in those less than 1cm.
2. Before RF ablation
3. In Bosniak type III indeterminate cystic renal masses (Figs. 1, 2)