GENERAL OVERVIEW OF RENAL TUMORS. PowerPoint

This PowerPoint highlights the general overview of both benign and malignant tumors of the kidney

1. RENAL TUMORS Dr. Chipili B . Bsc.HB, MBChB, FZCMS (Urology)

2. Classification of Renal Tumors Pathological classification Malignant Benign Inflammatory Radiological classification Simple cystic Complex cystic Solid tumors

3. Malignant tumors Adult primary malignant tumors of the kidney are either of parenchymal origin or renal collecting system Renal cell carcinoma (RCC) arises from the parenchyma and is the most common adult malignancy of the kidney Transitional cell carcinoma (TCC) arises from the renal collecting system Other malignant tumors of the kidney are Sarcomas, Lymphomas, Pediatric tumors and Metastatic tumors to the kidney

4. Benign tumors Simple renal cyst Selected complex renal cyst Oncocytoma Angiomyolipoma Cortical and metanephric adenomas Mixed epithelial and stromal tumors Leiomyoma Rarer cystic nephromas

5. Inflammatory tumors Renal abscess Tuberculosis Infected renal cysts Focal pyelonephritis Xanthogranulomatous pyelonephritis Rheumatic granuloma

6. Pathological classification of renal masses

7. Risk of malignancy of renal masses Renal masses has a wide range of differential diagnosis Clinical evaluation is extremely important in assessing the risk of malignancy and metastatic potential This evaluation may include patient characteristics and mode of presentation, imaging characteristics, laboratory evaluation and renal mass biopsy The strongest predictors of malignancy are male sex and increasing tumor size Majority of renal masses are discovered incidentally on imaging

8. Radiographic evaluation of renal masses Radiographic evaluation of a renal mass is the strongest predictor of malignancy and metastatic potential CT scan with contrast provides the most accurate characterization of renal masses (gold standard) Contrast enhancement of 15 to 20 HU is indicative of renal cell carcinoma (RCC) Solid masses with substantial areas of negative CT attenuation (below – 20 HU) indicative of fat are diagnostic for angiomyolipoma (AML) An estimated GFR below 45 mL/min/1.75m² requires hydration before contrast administration

9. Radiographic evaluation of renal masses MRI is the alternative standard imaging modality for characterization of renal masses Enhancement of greater than 20% with IV gadolinium based contrast is suggestive of RCC Significant concern with MRI with gadolinium is uncommon but potentially serious complication of nephrogenic systemic fibrosis This is common in patients in CKD stages 4 and 5, significant kidney injury and multiple doses of gadolinium Gadolinium contrast is only used when estimated GFR is greater than 30 mL/min/1.73cm²

10. Radiographic evaluation of renal masses Ultrasonography is a non-invasive and inexpensive modality that can differentiate cystic and solid renal masses It remains an important modality in evaluation of renal masses Any renal mass that is clearly not a simple cyst on strict ultrasound criteria should be evaluated further by multiphasic CT scan Contrast enhanced U/S scan has shown promise in the evaluation of renal masses and may play an important role in CKD in the future

11. Strict ultrasonographic criteria for simple cyst The strict ultrasound criteria for simple renal cystic mass have been identified and include the following; Smooth cystic wall Round or oval shape without internal echoes Through transmission with strong posterior acoustic shadowing

12. General reporting on imagining Regardless of the modality used imaging should comment on the following Renal mass diameter in craniocaudal, transverse and anteroposterior Tumor morphology Enhancement of the mass Involvement or relation of the mass to the renal hilum, vein or collecting system Associated features such as retroperitoneal lymphadenopathy Presence or absence of abdominal metastases

13. Evaluation of cystic renal lesions Differentiation between benign renal cysts and cystic RCC is a common challenging problem in renal imaging Simple cysts are thin walled and fluid filled structures with nearly zero risk of malignancy Any renal cystic mass that is not a simple cyst on ultrasound should be further evaluated by CT scan without and with contrast Bosniak classification is a CT criteria that defines renal cystic lesions into distinct categories based on the likelihood of malignancy

14. Evaluation of cystic renal lesions The risk of malignancy increases with cyst complexity defined by the following; Wall thickness and contour of the lesion Number and thickness of any septa Amount and character of any calcification Density of fluid in the lesion Margination of the lesion Presence of solid components

15. Bosniak classification Bosniak classifies renal masses into 5 categories ranging from 1 to 4 Bosniak 1 lesions are uncomplicated simple benign cysts that are straightforward to diagnose on U/S, CT or MRI scans They are by far the most common renal cystic lesions In the absence of associated symptoms no treatment or surveillance is necessary Bosniak 2 lesions are minimally complex cysts with low risk of malignancy They include nonenhancing septate cysts, cysts with calcium in the wall or septum, infected cysts and hyperdense cysts

16. Bosniak classification Bosniak 2 is subdivided into category 2 that does not require surveillance and category 2F that mandates surveillance Bosniak 2F lesions have a 3% to 10% risk of malignancy Bosniak 3 lesions are more complex renal cysts that cannot be confidently distinguished from malignant neoplasm Bosniak 4 lesions have large cystic components, irregular, shaggy margins and solid enhancing components that provide definitive diagnosis of malignancy Surgical exploration is usually indicated in healthy Bosniak 3 or 4 lesions

17. Bosniak classification

18. Bosniak 2

19. Bosniak 3

20. Bosniak 4

21. Reference Lous R. Kavoussi , Andrew C. Novick, Alan W. Partin, Craig A. Peters, CAMPBELL-WALSH Urology , 12 th Edition, Chapter 97, Elsevier Saunders, USA.