How To Approach Renal Masses? - Differential Diagnosis On Image

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1 How To Approach Renal Masses? - Differential Diagnosis On Image Poster No.: C-1646 Congress: ECR 2015 Type: Educational Exhibit Authors: A. E. A. G. Costa, A. Gomes, A. Duarte, I. Távora; Lisbon/PT Keywords: Neoplasia, Diagnostic procedure, Ultrasound, MR, CT, Kidney DOI: /ecr2015/C-1646 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 18

2 Learning objectives Enumerate and systematically categorize the different renal masses and their etiology. To discriminate between benign and malignant renal mass. Describe their radiological features. Background Detection of renal lesions has increased with the utilization of different imaging techniques. There s a broad spectrum of renal mass lesions that can be divided in: 1. Cystic, the most common renal lesion (the use of the Bosniak classification allows their stratification); 2. Solid masses that can be of malignant or benign etiology; 3. Pseudotumors may mimic renal solid lesion and include inflammatory masses, trauma or hemorrhage, congenital anomalies or vascular disease. Findings and procedure details Accurate characterization of renal masses is essential in the management of these lesions, determining if the treatment should be surgical or more conservative. The different imaging modalities, including computed tomography, magnetic resonance and ultrasound play a crucial role in the evaluation and classification of renal lesions. In this exhibit the authors present a systematic pictorial review based on a retrospective review of cases in our Department, to illustrate the broad spectrum of renal masses. BENIGN LESION 1. Renal cysts Though the majority of cysts noted on imaging are simple renal cysts, there is a variety of complex cystic masses, which are to a degree indeterminate in nature. The Bosniak classification system has been widely used by both urologists and radiologists due to its clinical practicality. Using the lesion's morphology and Page 2 of 18

3 enhancement characteristics, each cystic renal lesion can be categorized into one of five groups (categories I, II, IIF, III, and IV) each with associated recommendations for patient treatment. Fig. 1 Page 3 of 18

4 Category I - Benign simple cyst - Simple fluid attenuation( 0-20 HU), Hairline-thin smooth wall, - No septa, calcification, or soft tissue component Category II - Benign, minimally complicated cyst - A few (1-2) thin (<1mm) septa, small or thin calcifications - Hyperdense cyst - Homogenous, exophytic - Hyperdense lesion (>20HU, typically 40-90HU ) - Size <3 cm - Sharp smooth margin without enhancement Fig. 5: Hyperdense cyst in the left kidney (arrow). On the right the unenhanced TC demonstrate the hyperattenuating nature of the lesion, and on the left in the nephrographic phase there's no enhancement of the cyst. Category IIF - Minimally complicated cysts that need follow-up - Well marginated cyst Page 4 of 18

5 - A number of thin or thick septa, with or without mild enhancement - Thick and nodular calcification - No enhancing soft tissue component - Size > 3cm - Completely intrarenal - Homogenous - High-attenuation lesion (>20HU, typically 40-90HU) - Recommended interval for follow-up - 6 and 12 months, then yearly for a minimum of 5 years Fig. 7: In the right kidney there's a small cyst (blue arrow) with two irregular and mildly ennhancing septa (Bosniak IIF). Also present a simples cyst (green arrow). Category III - Indeterminate cystic mass - Thickened irregular wall or septa with enhancement - Thick or irregular peripheral calcification - Multilocular nature Page 5 of 18

6 Fig. 6: Two indeterminate cystic lesion in the left kidney (arrows). The smaller one has several irregular, tick and enhancing septa. The larger lesion has a tick, irregular and enhancing wall. Category IV - Malignant cystic mass - Enhancing soft tissue component adjacent to but independent of the wall or septa 2. Renal angiomyolipoma - Varying amounts of mature adipose tissue, smooth muscle, and blood vessels. - 20% to 30% of AMLs are found in patients with tuberous sclerosis syndrome. - Associated with serious or fatal hemorrhage. - The diagnosis is made by detecting fat within a solid renal mass. - A small number of angiomyolipomas do not contain macroscopic fat (angiomyomas), and the imaging differentiation from a renal neoplasm is impossible. Page 6 of 18

7 - Angiomyolipomas rarely contain calcification, and, therefore, a diagnosis of angiomyolipoma should not be made if a lesion contains fat and calcium. Fig. 2: Large angiomyolipoma (arrow) in the left kidney complicated of hemorrhage (*) Fig. 3: Angiomyolipoma in the sinus of the right kidney invading the renal vein and the inferior vena cava 3. Oncocytoma The oncocytoma is the most common, benign, solid, non-fat-containing renal mass. - Imaging features such as a central stellate scar or "spoked-wheel" pattern of vascular supply to the tumor do not allow a specific imaging diagnosis. - RCC and oncocytoma can be indistinguishable. Page 7 of 18

8 - Oncocytomas enhance uniformly at CT, except for the central scar, if presente. - Calcification in an oncocytoma is rare. MALIGNANT LESIONS 1. Renal Cell Carcinoma (RCC) - Renal cell carcinoma is the most lethal of all urologic cancers. - Typically round to ovoid and circumscribed by a pseudocapsule of compressed parenchyma and fibrous tissue. - Cystic degeneration in 10% to 25% of RCCs. - Calcification can be stippled or in plaque form, and is found in 10% to 20% of RCCs. - Aggressive local behavior is not uncommon with RCC: - Invasion of the collecting system or renal capsule in 20% of cases. - The Gerota's fascia prevents local spread to adjacent organs or the abdominal wall, although some high-grade RCCs may penetrate this barrier. - Involvement of the venous system, is found in 10% of RCCs. - The vascular nature of RCC plays a special role in imaging of this tumor. - Clear cell renal cancers have higher early enhancement and a strong association with necrosis and retroperitoneal collateral circulation. - Papillary RCCs show homogeneous low-level enhancement on both CT and MRI. Page 8 of 18

9 Fig. 12: Renal cell carcinoma: small solid enhancing lesion (arrow) depicted in enhanced TC (A), T2 weighted MRI (B), after gadolinium administration (C) and T1 weighted MRI (D). The lesion has high signal in the diffusion weighted imaging (F) and low ADC values(e). Page 9 of 18

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12 Fig. 13: Renal cell carcinoma: Solid lesion in the left kidney (arrow) with bright enhancement. 2. Transitional Cell Carcinoma (TCC) TCC is the most common urothelial neoplasm and the second most common primary renal malignancy. - On unenhanced studies, the intraluminal portion of a lesion often shows increased attenuation - After contrast administration, the mass typically enhances, although to a lesser degree than normal renal parenchyma (and characteristically less than conventional RCC). - The interface between a TCC and adjacent normal renal parenchyma during the nephrographic phase is typically ill defined. - The parenchymal infiltration may be sufficient to replace large volumes of normal tissue or even the entire kidney, causing pronounced alterations of renal enhancement or even nonfunction - Excretory-phase images improves visualization of collecting system abnormalities - localized hydrocalices - caliceal "amputation" due to encasement, - calices distended by tumor ("oncocalices") - unopacified calices due to larger areas of parenchymal infiltration and replacement. Page 12 of 18

13 Fig. 8: Hyperattenuating lesion (right image) in the right kidney pelvis and the inferior calyces that enhances after contraste administration (left image). This imaging features are typical of a transitional cell carcinoma Page 13 of 18

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15 Fig. 9: Transitional cell carcinoma infiltrating the right kidney. 3. Lymphoma - Lymphoma can have a variable appearance and may on occasion resemble renal cell carcinoma. - Most frequently, it manifests as bilateral solid renal masses. - Characteristically, lymphoma often infiltrates into the kidney via the renal sinus or surrounds the kidney. - In up to 25% of patients, renal lymphoma represents contiguous spread from adjacent adenopathy into the kidney, - Hematogenous dissemination also occurs. Diffuse lymphomatous infiltration producing smooth generalized renal enlargement occurs in approximately 20% of patients, - On rare occasion, lymphoma may manifest as a solitary renal mass or a homogeneous infiltrating renal mass. - Lymphoma is a soft tissue attenuation mass that enhances homogeneously but less intensely than normal renal parenchyma Fig. 4: Lymphoma infiltrating the left kidney (arrow). Also evident are the large conglomerates of para-aortic adenopathies Page 15 of 18

16 4. Metastases - Metastatic disease to the kidney is the most common renal malignancy with lung, breast, and gastrointestinal tumors and melanoma representing the most common. - At CT, metastatic lesions are typically small, multifocal, and bilateral, exhibiting an infiltrative growth pattern. - The contrast enhancement of renal metastases is much less than that of normal renal parenchyma PSEUDOTUMORS - This group includes congenital anomalies and inflammatory masses, as well as vascular structures. - A renal pseudotumor represents normal renal tissue that may mimic a renal neoplasm. - Congenital pseudotumors are normal variants which include prominent renal columns of Bertin, renal dysmorphism, and dromedary humps. - Acquired pseudotumors represent hypertrophied normal renal parenchyma assuming a tumorlike appearance adjacente to parenchymal scarring. - Inflammatory masses, including focal pyelonephritis and renal abscess, may also mimic the appearance of a renal neoplasm. - Vascular anomalies, including renal artery aneurysm or arteriovenous fistula. Fig. 10: Renal abcess in the right kidney: there's a well defined mass of low attenuation with a thick, irregular and enhancing wall. Renal parenchyma around the abscess cavity is hypoenhancing. Associated fascial thickening is also seen. Page 16 of 18

17 Fig. 11: Arteriovenous malformation in the right kidney: On the bottom images is depicted a well defined lesion that has the same enhancement of the aorta in the arterial and venous phases. Also seen the clear enhancement of the inferior vena cava in the arterial phase. On the top images the sonographic evaluation shows a anecogenic lesion that on the colour Doppler has a mixing of lighter colors and the presence of coarse, mosaic like vibrational artifacts suggestive of an arteriovenous malformation Conclusion The radiologic evaluation is important in the diagnosis and management of renal masses, allowing to choose the best therapeutic approach. Personal information References Page 17 of 18

18 Vincent G. Bird and Victoria Y. Bird (2011). Radiologic Imaging of Renal Masses, Renal Cell Carcinoma, Dr. Hendrik Van Poppel (Ed.), ISBN: Dyer R, DiSantis D, McClennan B, Simplified Imaging Approach for Evaluation of the Solid Renal Mass in Adults. Radiology: Volume 247: Number 2-May 2008 Israel G, Bosniak M. How I Do It: Evaluating Renal Masses; Radiology 2005; 236: Page 18 of 18