BackgroundIn this study, we prospectively evaluate the diagnostic potential of a gallium-68 (68Ga) prostate-specific membrane antigen (PSMA)-binding ligand and positron emission tomography (PET) in detecting metastatic lesions in patients with renal tumour. The secondary aim was to determine whether the findings would result in the alteration of patient management.ResultsTen patients with renal lesion and potential metastatic disease on conventional imaging were recruited. Patients underwent PSMA PET in addition to standard imaging. Nine patients underwent nephrectomy and 4 patients underwent additional targeted biopsy to provide specimens for histopathological validation. There were 89 pathological lesions on CT, of which 32 were removed or biopsied for histopathological correlation. With PSMA PET, 86 PET avid lesions were identified with 36 samples being available for analysis. Thirty-five of 36 samples were positive for renal cell carcinoma deposits, whilst 1 sample was inconclusive for diagnosis on biopsy. For the histologically confirmed lesions, there were no false-negative PSMA PET lesions; however, CT was false negative in 11. In two patients, surgical strategies were changed based on PSMA PET findings.ConclusionsPSMA PET may potentially have a role in the preoperative staging of advanced renal cell carcinoma as PET detected multiple histologically proven metastatic lesions which were false negative on CT scanning, resulting in change in surgical strategies in some patients. We cautiously support a larger study to confirm these results and to assess the longitudinal impact on patient outcomes.Trial registrationAustralia and New Zealand Clinical Trial Registry (ANZCTR), ACTRN12615000854538.Electronic supplementary materialThe online version of this article (doi:10.1186/s13550-016-0231-6) contains supplementary material, which is available to authorized users.

Standard treatment of renal neoplasms remains surgical resection, and nephrectomy for localised renal cell carcinoma (RCC) still has the best chance of cure with excellent long-term results. For smaller renal masses, especially stage T1a tumours less than 4 cm, nephron-sparing surgery is often employed. However, small incidentally detected renal masses pose an important diagnostic dilemma as a proportion of them may be benign and could be managed conservatively. Renal oncocytoma is one such lesion that may pose little risk to a patient if managed with routine surveillance rather than surgery. Additionally, lower-risk RCC, such as small chromophobe RCC, may be managed in a similar way, although with more caution than the renal oncocytomas (RO). The ability to differentiate ROs from chromophobe RCCs, and from other RCCs with a greater chance of metastasis, would guide the physician and patient towards the most appropriate management, whether nephron-sparing surgical resection or conservative surveillance. Consistent accurate diagnosis of ROs is likely to remain elusive until modern molecular biomarkers are identified and applied routinely. This review focuses on the differentiation of renal oncocytomas and chromophobe RCCs. It summarises the history, epidemiology and clinical presentation of the renal neoplasms, explains the diagnostic dilemma, and describes the value, or not, of current molecular markers that are in development to assist in diagnosis of the renal neoplasms.