Characterization and management of various renal cystic lesions by sonographic features

Abstract

Renal cysts are common incidental findings in clinical practice. Most renal cysts detected in medical imaging are benign simple cysts. However, some are complicated by hemorrhage or infection or are associated with calcification. In these instances, difficulties can be encountered distinguishing the complicated cysts from cystic renal tumors such as cystic renal cell carcinoma, multilocular cystic nephroma, and mixed epithelial and stromal tumors. The Bosniak classification is widely used to categorize cystic renal lesions but is used to classify those discovered via computed tomography. Ultrasonography (US) and color Doppler US are the most frequently used imaging techniques for abdominal surveys and long-term follow-up because of their noninvasiveness, relatively low cost, wide availability, and frequently, lack of contrast medium. Herein, we review the features of various cystic lesions of the kidney that can be found using US, discuss differential diagnoses using US, and propose a feature-oriented algorithmic approach to classifying renal cystic lesions using US.

EFSUMB 2020 Proposal for a Contrast-Enhanced Ultrasound-Adapted Bosniak Cyst Categorization – Position Statement

“…The renal cystic lesion may have been found on a routine US examination, or have been seen on CT without adequate characterization, for instance during a CT examination for possible renal colic. A curved array transducer, with a frequency between 1 and 9 MHz is deployed although linear transducers with a higher frequency can also be used in the detection of superficial renal cysts [51]. Following B-mode US to identify lesion location and color Doppler US to assess vascularity, the best approach to perform the CEUS examination is determined.…”

Hemorrhagic Renal Cyst, a Case Report

“…1 If all of these ultrasound features are met, additional imaging does not always have to be obtained. 1,2 Simple renal cysts are usually benign, asymptomatic, and often appear as incidental findings on imaging. 2,3 Generally, the number of renal cysts increase as a person ages.…”

“…1,2 Simple renal cysts are usually benign, asymptomatic, and often appear as incidental findings on imaging. 2,3 Generally, the number of renal cysts increase as a person ages. 3 A renal cyst may be classified as a complex cyst when it fails to be defined as a simple cyst.…”

“…1 Calcifications can also form within the cyst, which can make it challenging to discriminate a simple cyst from cystic renal tumors. 2 Both malignant and hemorrhagic cysts often have irregular boarders and echogenic material within their walls and within the cyst. 4 On ultrasound, infected renal cysts are characterized by thickened walls sometimes with debris or gas.…”

“…3 To further distinguish hemorrhagic cysts from malignant tumors, a CT or magnetic resistance imaging (MRI) should be performed. 2 Computed tomography is more sensitive than ultrasound for identifying a renal mass, but ultrasound is effective for further characterizing a simple cyst from a complex cyst. 3,6 One study reported that CT, MRI, and MRI with diffusion-weighted imaging (DWI) had 100% sensitivity at identifying the presence of possible malignant renal lesions, but CT and MRI had lower specificity (66.9% and 68.8%) than MRI with DWI (93.8%).…”