MRI findings of sarcomatoid renal cell carcinoma in nine cases

PurposeTo assess the magnetic resonance imaging (MRI) features of a series of 9 cases of pathologically proven sarcomatoid renal cell carcinoma (SRCC).MethodsTwo radiologists in consensus retrospectively reviewed a spectrum of MRI features of nine cases of SRCC imaged at our institution between 2003 and 2009.ResultsSRCC had a mean diameter of 9.9 cm. All cases had an irregular or infiltrative morphology and demonstrated heterogeneous T2 signal intensity and enhancement. Internal necrosis was present in all cases, with four cases demonstrating >50% necrosis. Evidence of aggressive local behavior and/or distant spread was frequently observed.ConclusionsWe have presented the largest case series to our knowledge of the MRI appearance of SRCC, with the lesions tending to appear as large heterogeneous masses with internal necrosis and evidence of aggressive local or distant behavior. However, these imaging features are non-specific, and histology remains necessary to establish the diagnosis.