1. Renal masses can be malignant tumors like renal cell carcinoma in adults or Wilms tumor in children, or benign cysts or lesions. 2. Multiple renal masses may indicate conditions like polycystic kidney disease or metastases. 3. Imaging techniques like ultrasound, CT, MRI, and angiography are used to characterize renal masses and cysts, determine if they are solid or cystic, diagnose conditions like angiomyolipomas, and stage renal carcinomas.

1. Renal parenchyma masses Almost all solitary masses arising within the renal parenchyma are either malignant tumours or simple cysts . In adults the malignant tumour is almost certain to be a renal cell carcinoma . Whereas in young children the commonest neoplasm is wilms tumour . Other causes of renal mass include renal abscess , benign tumour , angiomyolipoma , hydatid cyst & metastasis . Occasionally column of Breton ( psuedotomour ) invagination of the normal cortical tissue in to the central part of the kidney seen as amass by US & IVU ..

2. Renal parenchyma masses Multiple renal masses : A- multiple simple cysts . B- polycystic diseases . C- malignant lymphoma . D- metastases . E- inflammatory masses .

3. Renal parenchyma masses Imaging technique: Ultrasound ( US ). IVU , CT , MRI & Angiography. US Simple cysts are very common in middle aged & elderly they are filled with clear fluid so appear echo free with echogenic sharp out line mass , most cyst are spherical they may be solitary or multple unilocular or have septation , some time haemorrhagic cyst show low level echoes in he dependant part , when the sonographer is sure that the cyst is simple cyst so it needs no further investigation , while cystic & solid mass need CT scan. Angiomyolipomas are fairly frequent incidenal finding as a small echogenic masses , so CT or MRI may be used to confirm the diagnosis . Solid mass look to out line , echogenicity, extension of the tumor to renal vein, IVC, liver, retroperitoneal, & to the opposite kidney .

4. Sign of renal mass in IVU 1- a rounded lucency in nephrogram . 2- bulging of renal out line . 3- displacement and / or distortion of major & minor calices . 4- calcification in a small proportion of renal carcinoma. Calcification in the wall of benign cyst is uncommon . Once a mass is seen or suspected at IVU the next step is using US or CT for the nature . It should be noted that any solitary mass in young child, or any mass that contain calcification, particularly if the calcification is more than just a thin line at the periphery is likely to be malignant tumour .

5. CT & MRI CT has proved very useful for : Differentiating cysts from tumors . Diagnosis of angiomyolipomas . Staging of the known renal carcinoma . Renal mass may be characteriyed on MRI but MRI is used for resolving special problem . At CT atypical simple cyst is spherical mass with imperceptable wall with homogenous interior of the cyst with attenuation value similler to waterwith sharp margin al these criteria are diagnostic value of simple cyst ,so need no farther investigation .. On MRI the a simple cyst appears as a well defined rounded mass with homogenous high signal seen on T2 – weighted & low signal on T1 – weighted with no enhancement . ..

6. CT & MRI Angiomyolopoma is accidental finding it is benign which rarely cause problem , on occasion it cause intra-peritoneal hemorrhage diagnosed by CT & MRI there fat content give confident diagnosis . Rena cell ca are approximately spherical & often lobulated the attenuation value of the tumour on scan with out contrast enhancement is often close to that of normal renal paranchyma , but necrosis may seen in low dencity mass with stippled calcification in & near the perifary . The CT diagnosis of renal cacinoma is usually sufficiently accurate that pre operative biopcy is rarely performed . The degree & appearance of any solid component within the cyst influences the risk of lesion being malignant, follow up the patient & in some center biopsy under CT guideness but this is not so practices Staging of renal Ca is usually by CT . MRI used for detection of the tumour cell in the renal vein & IVC & for solving problems but nowadays multidetector CT with sagital & coronal plane is used to see the relation of the mass to renal hilar vesseles help in partial resection of the kidney. .

7. Wilms tumour Most commonly presented with flank mass or local pain . It is bilateral in 10% of cases . It not regress spontaneously . Artrerigraphic pattern is non specific .

8. Urothelial tumors almost all tumors that arise within the collecting systems of the kidney are TCC ( transitional cell carcinomas ) & the tumors some times occur in multiple sides . Bladder tumors may be demonstrated,but is better evaluated at cystoscopy . IVU play an important roles in demonstrating upper tracts ( PCS & UR) & often poorly demonstrated in other imag.ing modalities . In IVU TCC can be seen as lobulated or very occasionally as fronded filling defects either project in to the lumen or surrounding by contrast ,it is easy to confuse with overlying gas shadow so tomography is required during IVU . DD of filling defects in the collecting system: 1- Gas bowel ( IVU ) . 2- Radiolucent stone . ( US , CT ) . 3- Tumour . ( IVU , CT ) . 4- Blood clot .( history , IVU ) .

9. Urothelial tumours US it is difficult to be seen because it is blend with renal sinuous fat , if it is large appear as a mass in the renal pelvis & can be DD it from renal stone . The tumour can be diagnosed by CT in some hospital CT urography is performed with three dimensional reformatting of the collecting system to demonstrate the location & extension of the tumour Urothelial tumour may obstruct the ureter if it is large & can be demonstrated on IVU or CT , if the tumour is not recognized retrograde or antegrade pyelography may demonstrate the tumour .