Objective: To determine the value of percutaneous biopsy in a UK cohort of patients with renal mass lesions, with particular reference to its utility for the prediction of histological cell-type, Fuhrman nuclear grade and necrosis. Patients and methods: From May 1999 to September 2009, 71 patients underwent renal mass biopsy (RMB), most for indeterminate renal masses or in those with a mass lesion and extrarenal malignancy. Approximately one-third were for small renal masses (≤4cm). Biopsy results were correlated with final surgical specimen pathology or with the outcome of surveillance in those not receiving surgery. Results: Of 71 biopsies, there were 65 (91.5%) considered diagnostic biopsies, of which 59 (90.8%) were malignant and 6 (9.2%) were benign. 30 patients with biopsy-proven malignancy underwent extirpative surgery, with a diagnostic accuracy for biopsy of 100%. Accuracy of RMB for histological sub-type, Fuhrman nuclear grade and tumour necrosis was 80.0%, 52.3% and 80.0%, respectively. Bleeding complications were seen in 2 (2.8%) patients, and there were no cases of needle track seeding. Conclusion: RMB is a safe and accurate method for determining underlying malignancy, with an acceptable non-diagnostic rate. Although concordance for histological tumour sub-type and necrosis was reasonable, values for nuclear grade were less reliable.

Objectives A community of practice was described by Lave and Wenger as a mutual engagement using a shared repertoire of resources to attain a shared goal. This study explored the extent to which NHS workplaces function as communities of practice for core medical trainees. Methods All core medical trainees in one region were invited to a semi-structured interview. A framework was produced using communities of practice themes and a hybrid deductiveinductive method used for data analysis. Results NHS workplaces function as communities of practice by enabling engagement and by formation of mutual relationships. Joint enterprise was evidenced by multidisciplinary team working. Full participation was limited by service provision and short training rotations. Conclusions Trainee attendance in clinic and procedure lists should be facilitated. Trainees should be enabled to 'act up' as registrar. Flexibility is needed in jobs by allowing swaps between trainees and the facilitation of 'taster weeks'.