Active surveillance of small renal masses

Abstract

Most renal masses incidentally detected by cross-sectional images are benign, being mainly cysts, and if they are malignant, they are indolent in nature with limited metastatic potential. Enhanced renal masses less than 4 cm in size are known as small renal masses (SRMs), and their growth rate (GR) and the possibility of developing metastasis are extremely low. Delayed intervention of SRMs by closed and routine imaging follow-up known as active surveillance (AS) is now an option according to urological guidelines. Radiologists have a key position in AS management of SRMs even unifocal and multifocal (sporadic or associated with genetic syndromes) and also in the follow-up of complex renal cysts by Bosniak cyst classification system. Radiologists play a key role in the AS of both unifocal and multifocal (sporadic or associated with genetic syndromes) SRMs as well as in the follow-up of complex renal cysts using the Bosniak cyst classification system. Indeed, radiologists must determine which patients with SRMs or complex renal cysts can be included in AS, establish the follow-up radiological test algorithm to be used in different scenarios, perform measurements in follow-up tests, and decide when AS should be discontinued. The purpose of this article is to review the indications and management of AS in SRMs, especially focused on specific scenarios, such as complex renal cysts and multifocal renal tumors (sporadic or hereditary). In this work, the authors aimed to provide a thorough review of imaging in the context of active surveillance of renal masses.

Contrast‐enhanced ultrasound (CEUS) of benign and malignant renal tumors: Distinguishing CEUS features differ with tumor size

“… 2 Solid localized renal tumors larger than 4 cm were defined as a large renal mass (LRM). 3 According to the eighth edition (2017) of the TNM staging system, all histologic variants of RCC can be staged. In this system, tumors that are >4 cm but ≤7 cm along their longest axis and located to the kidney typically correspond to stage T1b RCC, while tumors >7 cm and limited to the kidney typically correspond to stage T2 RCC.…”

“…Renal cell carcinoma (RCC) is the most lethal malignancy of the genitourinary system which stems from the tubular epithelium of the renal parenchyma, 1 accounting for 80%–90% of renal malignancies 2 . Solid localized renal tumors larger than 4 cm were defined as a large renal mass (LRM) 3 . According to the eighth edition (2017) of the TNM staging system, all histologic variants of RCC can be staged.…”

Imaging Characterization of Renal Masses

“…In addition, there is an intense debate about the management of Bosniak III lesions as 50% of these patients undergo surgery for benign lesions. Moreover, active surveillance (AS) would be a good option for patients with Bosniak III and IV cysts [ 19 ], mainly in those <2 cm or in patients at high-risk for surgery, comorbidities, or limited life expectancy, as cystic RCCs are usually low-grade and low-stage tumors with better prognosis than solid RCCs [ 20 , 21 ].…”

Improving Renal Tumor Diagnosis with Computed Tomography and Artificial Neural Networks

“…Patients who underwent the surgery despite benign biopsies may have been chosen based on factors such as lesion growth and thus may not represent the entire population of patients with a benign diagnosis. For renal tumors with clinical stage T1a, according to TNM 8 th edition (equal to or less than 4 cm, small renal masses [SRMs]), active surveillance (AS) is emerging as a viable alternative to surgery [12]. SRMs have a very good prognosis, as it is documented that they grow at an average rate of 0.12-0.44 cm per year [13][14][15] and surgical results for small tumors are excellent [16].…”