Renal masses - the role of diagnostic imaging

Transcription

1 Renal masses - the role of diagnostic imaging Poster No.: C-2471 Congress: ECR 2015 Type: Educational Exhibit Authors: V. Rai#; Bjelovar/HR Keywords: Cysts, Cancer, Structured reporting, Ultrasound, MR, CT, Kidney DOI: /ecr2015/C-2471 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 24

2 Learning objectives To provide comprehensive and pictorial review of most common cystic and solid renal masses To differentiate cleary benign lesion from those that need surgical intervention or followup examinations Background The detection of renal masses has increased due to the increased use of imaging methods such as ultrasound ( US ), computed tomography ( CT ) and magnetic resonance imaging ( MRI ) performed for unrelated indications so the majority of renal masses are found incidentally. The most common type of renal mass are benign simple cysts which require no further work-up. However, completely solid or mixed solid and cystic renal lesions that enhace with contrast are likely to be malignant and need further evaluation and management. Renal masses Pathological renal massses: Renal Cyst serous renal cyst complicated renal cyst parapelvic and peripelvic renal cyst Inflammatory masses renal absces acute focal pyelonephritis Vascular masses haematoma Page 2 of 24

3 Neoplastic renal masses: Benign adenoma, oncocytoma angiomyolipoma Malignant renal cell carcinoma lympoma and leukemia metastases Findings and procedure details Imaging methods used in characterization of renal masses: US usually the first method safe, noninvasive, no ionizing radiation able to differentiate renal cysts from renal tumors ColorDoppler US is valuable in the assessment of venous involvement by renal tumors with IV contrast administration is modality of choice to evaluate renal masses usually performed as multistage study using thin slices CT - precontrast scans - important in identifying calcifications - arterial phase scans/corticomedullary phase - show early enhancement of renal tumors - nephrogram phase scan ( approximately 120 seconds following the onset of contrast injection ) - renal parenchyma is normally uniformally enhaced - pyelogram phase scan ( 3 to 5 minutes after contrast injection ) - shows contrast filling of the collecting systems and ureters Page 3 of 24

4 MRI helpful in staging renal cancers and in the evaluation of the indeterminate cystic renal mass superior to CT in differentiating benign thrombus from tumor thrombus and in identifying its extent useful in patients in whom CT is contraindicated ( children, pregnant woman, patients with an allergy to iodinated contrast media ) and for monitoring patients who have genetically increased risk of renal malignancy Renal masses: RENAL CYST SIMPLE/SEROUS most common type renal mass #found in half the population older than 55 commonly multiple and bilateral small are asymptomatic; large (> 4 cm) ocasionally cause obstruction, pain, hematuria or hypertension # US criteria: round or oval anechoic mass increased through transmission sharply defined thin or imperceptible cyst wall # CT signs: sharp margination with the renal parenchyma no perceptible wall homogeneous attenuation near water density (-10 to +10 HU) absence of contrast enhancement Page 4 of 24

5 MR criteria: homogeneous, sharply defined, round or oval mass homogeneous low signal intensity on T1WIs homogeneous high signal intensity similar to that of urine on T2WIs no enhancement after gadolinium administration # COMPLICATED CYST - simple renal cyst complicated by hemorrhage or infection # change in imaging characteristics makes differentiation from cystic renal tumors difficult BOSNIAK CLASSIFICATION SYSTEM I : simple cyst II : 1) cyst with delicate thin septations no more than 1-2 mm thick 2) cyst with delicate thin calcification in the wall or septum 3) cyst that is hyperdense (60-100HU) on CT because of high concentration of protein or blood breakdown products and smaller than 3 cm Category IIF: cyst with less characteristic findings and larger than 3 cm I and II # benign, no further imaging or follow-up needed IIF # imaging follow-up at 3, 6 and 12 months III : indeterminate lesions that may be malignant # thick irregular calcification, irregular margins, thick or enhancing septa, areas of nodularity, thick walls, multilocular appearance, solid nonenhancing areas hemorrhagic or infected simple cysts, multilocular cystic nephroma, multiloculated cysts, cystic forms of RCC considered suggestive of malignancy and should be biopsied or surgically explored Page 5 of 24

6 IV : necrotic cystic neoplasms or tumors that arise in the wall of a cyst#irregular solid nodules, irregular thick shaggy walls, septa with contrast enhancement of solid areas clearly malignant, require surgical treatment RENAL ABSCESS generally associated with symptomatic urinary tract infection, but it can also present with vague symptoms such as flank pain and weight loss immunocompromised and diabetic patients, patients with infected renal stones # higher risk of developing renal infection rupture of the renal abscess # infection of the perinephric space CT - modality of choice - the central portion of an abscess is of near fluid density with no contrast enhancement - often a thick irregular wall, which enhances together with inflammatory changes in the perinephric space - the presence of gas within a lesion is diagnostic of an abscess but very rarely seen # ANGIOMYOLIPOMA benign lesion composed of variable amounts of fat, smooth muscle and abnormal blood vessels spontaneously in the general population or associated with tuberous sclerosis the risk of hemorrhage is related to the size of the tumor # significantly higher in lesions greater than 4 cm in diameter US: circumscribed, highly reflective mass, more echogenic than the central sinus fat; - because of this high reflectivity, very tiny lesions can be detected with US - tumors with greater proportion of muscle and those with hemorrhage or necrosis may not be echogenic CT: fatty mass intermixed with areas of increased tissue density - the amount of fat present is variable and it can even be absent Page 6 of 24

7 - detection by CT of even a small amount of fat within a renal mass establishes the diagnosis of angiomyolipoma (15HU) - if there is coexistent hemorrhage, CT and other techniques may not provide an accurate preoperative diagnosis - important to assess the relationship of the fat to the remainder of the tumor to be certain that the fat is intratumoral, and not perirenal fat that has been engulfed by an expanding renal cell carcinoma # ONCOCYTOMA previously have been considered benign, now recognized that they can metastasize often asymptomatic at presentation tend to be large # 1 to 20 cm in diameter usually solitary and unilateral US: solid mass with internal echoes, occasionally a stellate hypoechoic centre; the echogenicity of the mass can be variable CT: well-defined solid mass; when large, can contain a low attenuation central scar; large lesions can extend into and engulf the perinephric fat and can be mistaken for angiomyolipomas RENAL CELL CARCINOMA 85% of all malignant renal tumours bilaterally in 3-5% of cases any solid renal mass should be considered suspect for RCC! US:heterogeneous, hypoechoic or mildly hyperechoic mass areas of hemorrhage and necrosis appear cystic Doppler # echogenic material in the vein associated with partial or complete absence of blood flow # tumor thrombus CT:heterogeneously enhancing mass less dense than enhanced renal parenchyma - low density areas - hemorrhage and necrosis Page 7 of 24

8 - discrete soft tissue nodules in the perirenal fat-highly predictive of tumor spread into the fat - venous tumor thrombus - low-density filling defect within a contrast enhanced vein that is usually enlarged MRI: isointense or hyperintense (hemorrhage) compared with renal parenchyma on T1WIs - distinct enhancement with gadolinium administration - #most are heterogeneous on T2WIs - staging accuracy of MR and CT is about equal treatment: radical nephrectomy with removal of the renal fascia and its contents (kidney, adrenal gland, perinephric fat, hilar lymph nodes) small tumors (< 3 cm) - partial nephrectomy hemorrhage, necrosis - common; calcifications - 10%; growth into the renal vein - 30%; extension into the IVC % detection of venous invasion is critical to surgical planning metastases - in 40% at diagnosis (lung, local lymph nodes, liver, bone, adrenal glands, opposite kidney) # LYMPHOMA primary renal lymphoma is rare kidney is commonly involved by metastatic lymphoma or by direct invasion (non-hodgkin) CT: homogenous, round, poorly enhancing mass diffuse disease enlarging the kidney, multiple bilateral solid renal masses, perirenal tumor surrounding the kidneys, solitary bulky tumor, tumor invasion into the renal sinus # METASTASES most appear as multiple, bilateral, small, irregular renal masses Page 8 of 24

9 usually hypovascular on CT and do not tend to demonstrate calcification or renal vein invasion some are large, solitary and hard to differentiate from RCC lung, breast, colon carcinoma; melanoma - late in the course of the disease # # Images for this section: Page 9 of 24

10 Fig. 1: US demonstrates a well-defined lesion with enhanced through transmission and thin septa - Bosniak class II Page 10 of 24

11 Fig. 2: CT shows complicated cyst in left kidney, 3.2 cm, with hyper- and hypodense areas, following contrast medium there is no significant change in the appearance or density of the mass # cyst with septa and hemorrhagic zones; no change during a 2-year period - Bosniak IIF simple cyst, 1.9 cm, hypodense, no contrast enhancement, sharply marginated - Bosniak I Page 11 of 24

12 Fig. 3: MRI shows complicated cyst in right kidney, 2.4 cm, irregular shape, with septa; high intensity signal on T2, areas of high intensity signal on T1, no contrast enhancement - Bosniak IIF Page 12 of 24

13 Fig. 4: CT shows cyst in left kidney, 12 cm, with solid nodular areas in the wall which show contrast enhancement - Bosniak IV Page 13 of 24

14 Fig. 5: CT shows multiple bilateral hypodense cystic masses, some containing thin septa and partially calcified walls; no contrast enhancement; Bosniak II Page 14 of 24

15 Fig. 6: CT demonstrates poorly enhancing masses in left kidney; the central portion is of near fluid density; thick wall - renal abscess Page 15 of 24

16 Fig. 7: detection by CT of even a small amount of fat within a renal mass establishes the diagnosis of angiomyolipoma ; it is important to be certain that the fat is intratumoral Page 16 of 24

17 Fig. 8: CT - well-defined solid enhancing mass lesion - oncocytoma Page 17 of 24

18 Fig. 9: US shows hypoechoic solid renal mass - RCC Page 18 of 24

19 Fig. 10: CT demonstrates tumorous mass in right kidney with thrombotic filling defect of renal veins - RCC Page 19 of 24

20 Fig. 11: tumorous mass in right kidney spreading in right renal vein and IVC; tumor thrombus in IVC Page 20 of 24

21 Fig. 12: MRI shows solid tumorous mass in right kidney with central necrosis and spread into perinephric space Page 21 of 24

22 Fig. 13: CT shows nodular poorly enhancig masses of left kidney - lymphoma Page 22 of 24

23 Fig. 14: heterogeneous irregular masses on CT in both kidneys and liver - metastases Page 23 of 24

24 Conclusion US is the first imaging method CT is modality of choice to evaluate renal masses Bosniak classification system is used for characterization of cystic renal masses MRI is useful in staging renal cancers and in the evaluation of the indeterminate cystic renal mass; superior to CT in differentiating benign thrombus from tumor thrombus and in identifying its extent any solid renal mass should be considered suspect for RCC! # The idea of this educational exhibit is to help young radiologists with characterization of simple and complex cystic lesions as well as solid renal masses. The major question to be answered is whether the mass represents a surgical or nonsurgical lesion or if follow-up studies are necessary. Careful evaluation of imaging finding combined with the patient's history should assist the radiologist in making the proper diagnosis. Personal information Valentina Rai#, MD, radiology resident, "General Hospital Bjelovar", Bjelovar, Croatia References Brant W.E., Helms C.A.: Fundamentals of Diagnostic Radiology, Lippincott Williams & Wilkins 2007 Silverman SG, Cohan RH, et al. In: CT Urography: An Atlas. 1st ed. Philadelphia, Pa: Lippincott Williams and Wilkins; Page 24 of 24