Class I cysts have a thin or imperceptible wall, no septations, and is of fluid density.
Class II cysts still demonstrate no enhancement, but may have thin septa and high density (60 to 90 HU). They may demonstrate calcification or minimal irregularity.
Class III cysts have increased irregularity, thick septa with or without enhancement, or manifest as a nonenhancing multilocular mass.
Class IV cysts are malignant lesions with irregularity and enhancement and necrotic/cystic components.
Various levels of further evaluation are required for Classes II-IV, but no followup for simple cysts is recommended, as their benignity is almost certain. Simple cysts are thought to arise from benign exuberant proliferation of tubular epithelium along with excessive fluid excretion. These lesions can grow to be quite large (several centimeters) causing mass effect, or become infected, but in the vast majority of cases will cause no physical symptoms.
Radiologic overview of the diagnosis:
Cysts can manifest on a variety of modalities, including nephrotomography, nuclear medicine renal scans, MR, CT, ultrasound and even occasionally by plain film. IVP findings can include the "beak" or "claw" sign of parenchymal deformity at the edges of the cyst. CT is the best imaging modality for diagnosis, with a sensitivity nearing 100%. Noncontrasted and 90 second delay post-contrast images are recommended for accurate CT characterization. Ultrasound sensitivity is likely as high as 98% and can often better define the internal characteristics of cysts, but this study is more limited by patient body size.
Key points:
- Simple cysts are very prevalent in older adults (up to 50% in those older than 50).
- Cysts can manifest on a variety of imaging modalities, including IVP.
- CT and ultrasound are best for diagnosis and accurate characterization.
- Bosniak classification of Classes I-IV are used to characterize the level of likelihood of cyst malignancy.
.jpg)
Posts
