Developmental Renal Pseudotumours
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1) A 30-year old woman presented with menorrhagia and anemia. Imaging revealed a mass in her kidney concerning for renal cell carcinoma. 2) Further workup including ultrasound, CT scan and lab tests showed the mass enhanced similarly to normal renal parenchyma. 3) Upon review of literature, these findings were consistent with a "renal pseudotumor" - a mass that mimics a tumor radiologically but is actually normal or benign renal tissue. Pseudotumors can represent developmental variants, infections, or other benign etiologies.
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Developmental Renal Pseudotumours
- 1. RENAL PSEUDOTUMOURS Presenter: DR. MUHIBULLAH BANGASH Supervisor: Dr. SYED MUHAMMAD NAZIM
- 2. Case scenario • 30 years old nulliparous lady married for 8 years • No known comorbid • Presented with menorrhagia for last 10 days. • No prior history of any bleeding disorders.
- 3. Examination • Abdomen: • Soft, non tender abdomen • No visceromegaly • P/V examination: • moderate p/v bleeding • normal cervix and anteverted uterus • Vitals: • Pulse = 110/min • BP = 130/70 mmHg • Temp: 36 °C • RR = 16/min
- 4. Work-up • Labs: • Hb of 5.5 gm/dl • HCT: 17.4 • Serum Creatinine was 1.1 mg/dl • β-HCG < 2.0 mIU/ml • Normal coagulation profile
- 5. Work-up • Labs: • Hb of 5.5 gm/dl • HCT: 17.4 • Serum Creatinine was 1.1 mg/dl • β-HCG < 2.0 mIU/ml • Normal coagulation profile
- 6. Ultrasound
- 8. Contrast enhanced CT with RCC protocol
- 9. • Approximately 50% of middle-aged adults have an incidental renal lesion. • The most common incidental renal lesion is a cyst, and the prototypical solid lesion seen is the renal cell carcinoma (RCC). • However these lesions have occasionally turned out to be benign lesions on histopathology when patients underwent unnecessary biopsies and even nephrectomies based on radiological appearance of malignancy. Silverman SG, Israel GM, Herts BR, et al. Management of the incidental renal mass. Radiology 2008; 249:16–31.
- 10. LITERATURE
- 11. ‘’We have encountered regrettable situations in 6 patients with renal pseudotumours, defined as a real or simulated mass in the kidney radiologically resembling neoplasm but histologically consisting of normal renal parenchyma.’’ Dr Benjamin Felson FELSON B, MOSKOWITZ M. Renal pseudotumors: the regenerated nodule and other lumps, bumps, and dromedary humps. American Journal of Roentgenology. 1969 Dec;107(4):720-9.
- 12. • 6 cases were operated • 3 underwent nephrectomies • 3 nephrectomies averted as absence of neoplasm was recognized intraoperatively
- 13. Definition: Renal lesions that mimics neoplasm on imaging but are actually comprising of benign or normal tissue are known as “Renal Pseudotumors.” Bhatt S, MacLennan G, Dogra V: Renal pseudotumors. Am J Roentgenol 188(5):1380-1387, 2007 Silverman SG, Israel GM, Herts BR, et al. Management of the incidental renal mass. Radiology 2008; 249:16–31.
- 14. TYPES •Developmental •Infectious •Granulomatous •Vascular •Miscellaneous Bhatt S, MacLennan G, Dogra V: Renal pseudotumors. Am J Roentgenol 188(5):1380-1387, 2007 Silverman SG, Israel GM, Herts BR, et al. Management of the incidental renal mass. Radiology 2008; 249:16–31.
- 15. DEVELOPMENTAL PSEUDOTUMOURS • Persistent fetal lobulation • Prominent column of bertin • Dromedary hump • Cross-fused renal ectopia • Renal hilar lip Bhatt S, MacLennan G, Dogra V: Renal pseudotumors. Am J Roentgenol 188(5):1380-1387, 2007 Silverman SG, Israel GM, Herts BR, et al. Management of the incidental renal mass. Radiology 2008; 249:16–31.
- 16. Embryology • Pronephros: Do not function at all– degenerate ultimately • Mesonephros: Function only during early fetal period for a very short duration. • Ureteric bud grows from distal end of mesonephros and stimulate the formation of Metanephros (permanent kidneys)
- 18. Diagnostic challenge for both Radiologists and Surgeons!!
- 19. Workup INITIAL LAB • Urinalysis • CBC • Electrolytes • Renal profile • LFTs • Serum calcium IMAGING • Ultrasound • Contrast enhanced CT scan • IVU • MRI • Contrast enhanced US
- 20. Conventional Ultrasound with Doppler • Ultrasonography is often the initial modality for imaging of the kidneys. • Renal pseudotumours appear as ischoechoic or hyperechoic solid well- circumscribed lesions on conventional greyscale US with normal or increased vascularity on colour doppler. Paspulati RM, Bhatt S. Sonography in benign and malignant renal masses. Ultrasound Clinics. 2006 Jan 31;1(1):25-41.
- 21. Intravenous Urography • Pseudotumors appear as an intrarenal mass that displaces and stretches the collecting system and may cause filling defects. • A small- to medium-sized tumor may be missed by excretory urography. • Low sensitivity and specificity. FELSON B, MOSKOWITZ M. Renal pseudotumors: the regenerated nodule and other lumps, bumps, and dromedary humps. American Journal of Roentgenology. 1969 Dec;107(4):720-9.
- 23. Contrast enhanced CT-scan • It has become the imaging of choice for diagnosis and staging of suspected renal cell cancer. • Renal pseudotumours appear as solid enhancing masses similar to the surrounding renal parenchyma. Bhatt S, MacLennan G, Dogra V. Renal pseudotumors. American Journal of Roentgenology. 2007 May;188(5):1380-7.
- 24. MRI • Renal pseudotumours appears as a solid enhancing mass arising from the kidney on Gadolinium- enhanced MRI scan. • Similar signal intensity and identical homogeneous enhancement as that of normal renal cortex. Bhatt S, MacLennan G, Dogra V. Renal pseudotumors. American Journal of Roentgenology. 2007 May;188(5):1380-7.
- 27. Contrast Enhanced Ultrasound • A contrast agent consisting of a stabilized aqueous suspension of Sulfur hexafluoride microbubbles with a phospholipidic shell. • A dose of 2.4 mL of contrast medium is rapidly administered through an antecubital vein, immediately followed by a 10-mL flush of saline solution (0.9% NaCl) and examination of suspected renal pseudotumor perfusion is evaluated in real time. • Microbubble rupture with high-acoustic pressure pulse was used to evaluate their refilling in order to evaluate reperfusion of suspected pseudotumor in comparison with corticomedullary tissue.
- 28. Contrast-enhanced Doppler ultrasonography • cost-effective • noninvasive imaging • Can be used for follow up • no risk of nephrotoxicity • minimally invasive • lacks radiation burden Paspulati RM, Bhatt S. Sonography in benign and malignant renal masses. Ultrasound Clinics. 2006 Jan 31;1(1):25-41.
- 30. Persistent fetal lobulation • Kidney during embryonic life shows lobar development comprising of multiple individual lobes that fuse together.a • These areas of fusion are marked by indentation on the cortex of kidney that usually disappear by the age of 5 years resulting in an adult kidney with smooth appearing surface. b • Each fetal lobe is made up of a medullary pyramid surrounded by cortex on all sides and drained by a single calyx. a. Hodson J: The lobar structure of the kidney. Br J Urol 44:246-261, 1972 b. Friedland GW, Devries PA, Nino-Murcia M, et al: Congenital anomalies of the urinary tract. Anomolies in structure, in Pollack HM (ed): Clinical Urography. Philadelphia, Saunders, 1990, pp 638-64.9
- 31. Persistent fetal lobulation • It is a normal variant seen occasionally in adult kidneys. • It occurs when there is incomplete fusion of the developing renal lobules. • It is often seen on ultrasound, CT or MRI as smooth indentations of the renal outline in between the renal pyramids. Patriquin H, Lefaivre JF, Lafortune M, Russo P, Boisvert J. Fetal lobation. An anatomo- ultrasonographic correlation. Journal of ultrasound in medicine. 1990 Apr 1;9(4):191-7.
- 32. Completion of the smoothing follows during childhood by the increase in volume of the connective tissue and the increase in size of the nephrons without any change in their number 1.Renal medulla 2.Calix minor 3.Renal cortex Patriquin H, Lefaivre JF, Lafortune M, Russo P, Boisvert J. Fetal lobation. An anatomo- ultrasonographic correlation. Journal of ultrasound in medicine. 1990 Apr 1;9(4):191-7.
- 33. BEEF KIDNEY
- 35. Prominent Column of Bertin • A column of Bertin is the extension of renal cortical tissue which separates the pyramids, and as such are normal structures. They become of radiographic importance when they are unusually enlarged and may be mistaken for a renal mass. • Ideally, the term hypertrophied column of Bertin or prominent column of Bertin should be used to avoid confusion. • Hypertrophied cortical tissue may appear as an isohyperechoic to mildly hyperechoic “mass” on US that is usually perpendicular to the renal capsule with a smooth margin mimicking a renal neoplasm.
- 37. Dromedary Hump • These are prominent focal bulges on the lateral border of the left kidney. • They are normal variants of the renal contour due to splenic impression onto the superolateral left kidney. • A dromedary hump must have the same radiological features as the adjacent cortex, whatever the modality. • Named after the dromedary camel which is a well known member of the camel family that has a single hump.
- 40. Cross-fused renal ectopia • Crossed fused renal ectopia essentially refers to an anomaly where the kidneys are fused and located on the same side of the midline.
- 41. Renal Hilar Lip • A rare developmental anomaly of the kidney caused by an infolding of the cortex at the level of the renal sinus and appears thicker resembling a mass.
- 42. Splenorenal fusion • Splenorenal fusion refers to the presence of heterotopic splenic tissue in the renal capsule. • It may arise as a developmental anomaly secondary to the fusion of nephrogenic mesoderm and splenic anlage in the second month of gestation. • It may also be secondarily acquired as a result of splenosis after trauma or splenectomy, and the presence of a renal mass in such patients should raise the suspicion of splenosis.
- 44. Learning Points • Renal Pseudotumors include some of uncommon anatomic variations that mimic focal renal lesion on ultrasonography. • Radiologist can make potential errors during image interpretation of renal pseudotumours especially on conventional and power Doppler ultrasound scan.
- 45. Learning Points • To reach a secure diagnosis, a cross sectional imaging such as CT or MRI should be done. • Contrast enhanced ultrasound (CEUS), where available can be a credible alternative to these imaging. • A high index of suspicion for renal Pseudotumors may help avoid unnecessary additional interventions.
- 46. Have a good day…….!
Editor's Notes
- 202-03-50
- 202-03-50
- US scan showing persistent fetal lobulation mimicking solid lesion in bilateral kidneys Report: Multiple enlarged well-circumscribed heterogenous solid appearing masses are identified in the kidneys. These are showing significantly increased vascularity on colour Doppler. The one at the interpolar region of right kidney measures 36 x 27 mm in size. The larger one at the interpolar region of left kidney measures 54 x 34 mm in size. The other at the lower pole of left kidney measures 29 x 23 mm.
- Persistent fetal lobulation shown on coronal and delayed axial sections Report: Both kidneys are malrotated with irregular contour and persistent fetal lobulations. The left kidney appears relatively small in size with multifocal cortical scarring. No suspicious mass lesion identified in either kidneys to suggest neoplastic lesion. Bilateral renal veins and arteries are intact. There is no adjacent or distant lymphadenopathy.
- Dr Benjamin Felson, one of the outstanding diagnostic radiologists of his time, died suddenly of a heart attack October 22, 1988, while working on a manuscript. At his death he was professor emeritus of radiology at the University of Cincinnati College of Medicine, where he had served as director of the department of radiology for 22 years. 6 cases were operated 3 underwent nephrectomies 3 nephrectmoies averted as absence of neoplasm was recognized intraoperatively
- Pronephros: (1 to 4 week) (7 to 10 solid cell groups),Degenerate ultimately Mesonephros: 4-8 week 40 in number, upper thoracic to L3, craniocaudal, (mesonephric duct, wolffian + M tubule + glomerulus) Mesonephros: ultimately form rete testis, appendix testis, epididymis, ductus deferens(epoophoron and paroophoron) Paramesonephric duct : fallopian tube, uterus, upper vagina Metanephros starts 5 week Urine production starts week 10
- Determining whether a space-occupying renal mass is benign or malignant can be difficult. Imaging studies should be tailored to enable further characterization of renal masses, so that nonmalignant tumors can be differentiated from malignant ones.
- Ultrasonographic examination can be useful in evaluating questionable cystic renal lesions if CT imaging is inconclusive. The most efficacious diagnostic study is scanning with radionuclide (2,3-dimercapto-succiriic acid [DMSA]). On imaging, these pseudotumors, which are made up of excess renal cortical tissue, appear as areas of normal or increased activity and should be distinguished readily from other space-occupying lesions that produce cold areas.
- Unenhanced phase, the Corticomedullary phase of enhancement, 25-70 seconds after administration of contrast, renal cell carcinomas demonstrate variable enhancement, usually less than the normal cortex, The nephrogenic phase (80-180 seconds) is the most sensitive phase for detection of abnormal contrast enhancement. Excretory phase is of less worth, but important in assessing the collecting system anatomy especially if the candidate is a potential candidate for a partial nephrectomy. The 2009 American Urological Association (AUA) guideline for the management of the clinical T1 renal mass recommends a high-quality cross-sectional CT or MRI, first without and then with intravenous contrast if renal function is adequate. The objectives are as follows.[20] : Rule out angiomyolipoma Evaluate for locally invasive features Study the involved anatomy Determine the status of the uninvolved kidney and its vasculature
- The NCCN guideline recommends abdominal MRI as an alternative to CT for renal mass detection and staging in cases where the use of contrast is contraindicated because of allergy or renal insufficiency.
- T1 fat saturated gadolinium enhanced
- Contrast-enhanced Doppler ultrasonography appears promising as a cost-effective, noninvasive imaging technique in the characterization and follow-up of indeterminate renal mass lesions. CEUS exhibits no risk of nephrotoxicity or NSF, is minimally invasive, and lacks radiation burden CEUS measurements can be influenced by the location of the lesion (deep vs. superficial), bowel gas production or obesity of the patient (due to the significant loss of image quality). In addition, since there is no clear definition of image interpretation, qualified urologists or radiologists are required with sufficient experience to reduce the inter-observer reliability. Furthermore, CEUS is user dependent and, since it is not a cross-sectional imaging technique, there is a risk of overlooking some lesions. Finally, the FDA does not yet approve the use of microbubbles in renal masses for radiological indications
- an early corticomedullary phase is useful to show cortical enhancement similar to that of adjacent parenchyma in case of pseudotumor or to identify a brief arterial phase in hypervascular small RCC. On the other hand, late corticomedullary phase is also fundamental to show the normal enhancement of the medullary parenchyma and the hypovascular renal masses as metastases and infiltrative carcinomas usually are.
- In the fetus, renal lobes (consisting of a pyramid of collecting tubles and overlying cortex) are separate, eventually fusing to form the typical reniform shape with a smooth surface. These lobes can persist to produce a lobulated cortical surface, each representing a pyramid and overlying cortex with a valley in between as compared to renal scarring due to vesico-ureteric reflux, where there are cortical defects overlying the pyramids especailly at the upper and lower poles
- Renal medulla Calix minor Renal cortex
- Add more about fetal lobations
- DMSA (dimercaptosuccinic acid) isotopic examination can also be used to confirm the presence of a dromedary hump and exclude malignancy as the former shows normal uptake whereas the latter does not.
- It results as a consequence of abnormal renal ascent in embryogenesis with fusion of the kidneys within the pelvis. It is thought to occur in the first trimester, at around 4th-8th week of fetal life (In a normal situation the kidney reaches its appropriate position at L2 level at the end of the 2nd month). Some evidence supports that an abnormally situated umbilical artery prevents normal cephalic migration. Another theory is that the ureteric bud crosses to the opposite side and induces nephron formation in the contralateral metanephric blastema. The result is a single renal mass with two collecting systems being located on one side of the abdomen. Left-to-right ectopy is thought to be three times more common. Types: type a: inferior crossed fusion type b: sigmoid kidney type c: lump kidney type d: disc kidney type e: L-shaped kidney type f: superiorly crossed fused IVU, URETEROGRAM, US, CT, Angiography complications such as nephrolithiasis, infection, and hydronephrosis approaches ~50%.
- The tests with the greatest reported specificity for the diagnosis of both normal and ectopic splenic tissue are 99mTc-sulfur colloid liver-spleen scintigraphy, 99mTc-labeled heatdamaged erythrocytes spleen scintigraphy, and ferumoxide-enhanced MR imaging, which show uptake by the splenic tissue and help make a more-definitive diagnosis. With increased awareness of accessory splenic tissue in various locations, especially in the regions surrounding the spleen, and ever-improving imaging capability, radiologists should be aware of this entity to avoid unnecessary biopsy or surgery.