Cystic renal neoplasms in adults: Current imaging update

Abstract

APPLIED RADIOLOGY © n 23 January 2015 Cystic neoplasms of the adult kidney are a diverse group of pathologically distinct tumors with variable clinico-biological profiles. Cystic tumors may be histo-biologically benign or malignant. Benign tumors include lymphangioma, cystic nephroma, and mixed epithelial and stromal tumor. Cystic renal cell carcinoma (RCC), multilocular cystic RCC, and primary renal synovial sarcoma constitute malignant cystic neoplasms. Recent advances in pathology have expanded the spectrum of cystic renal neoplasms. Indeed, new tumors such as tubulocystic RCC, acquired cystic disease-associated RCC, and angiomyolipoma with epithelial cysts have been identified as ‘distinct tumor entities’ as they show characteristic pathological and imaging findings (Table 1).1,2 Radiologists play an important role in the detection, characterization, treatment follow-up, and long-term surveillance of cystic masses. The major responsibility of radiologists is to segregate renal cystic masses into three different groups: lesions that can be safely ignored, lesions that need regular follow-up, and masses that require surgical resection. In this article, we will describe the imaging findings of various cystic renal neoplasms and how we can differentiate these from benign cysts; additionally, current imaging and pathological update regarding select tumors will also be presented.