2. UroToday Home
  3. Recent Abstracts
  4. Urologic Oncology
  5. Renal Cancer

Common and less-common renal masses and masslike conditions, "Beyond the Abstract," by Marinos Kontzialis, MD, et al

BERKELEY, CA (UroToday.com) - Incidental renal lesions are found in up to approximately 50% of middle-aged adults. The most common renal lesion is a cyst, while the lesion that needs to be excluded is renal cell carcinoma (RCC). Renal lesions can be divided into non-neoplastic and neoplastic. We briefly review these lesions in this commentary.[1]

Non-neoplastic lesions include parapelvic cysts. Parapelvic cysts demonstrate imaging characteristics identical to simple cysts, and can be mistaken for hydronephrosis due to their vicinity to the collecting system.[2] Lack of communication with the renal pelvis establishes the diagnosis.

"...familiarity with other common and less common renal lesions is essential for improved diagnostic accuracy."

In acute pyelonephritis, imaging is usually reserved for complications, and CT is excellent for gas, calculi, hemorrhage, obstruction, and abscess formation. Striated nephrogram on contrast-enhanced CT is typical. Focal pyelonephritis can mimic a mass lesion, and clinical presentation is very helpful in excluding a neoplasm.[3]

Xanthogranulomatous pyelonephritis is an uncommon inflammatory condition in the setting of chronic obstruction and infection. It is associated with staghorn calculi and renal enlargement. XGP can be focal or diffuse; the focal form usually presents as focal low attenuation, and it can be difficult to differentiate from a renal mass. Accompanying findings such as renal calculi and abscesses are helpful hints.[3]

Lymphoplasmacytic renal focal lesions can be encountered in the setting of autoimmune pancreatitis. Renal findings are nonspecific and include bilateral, hypovascular wedge shaped masses.[4] Characteristic findings in the pancreas (enlargement with hypodense halo) strongly suggest this diagnosis. Confirmatory studies include serum IgG4 and biopsy. The lesions usually respond to steroids.

Renal scars after infection or infarction can mimic a mass, and contrast enhanced CT or MR with renal protocol is used for diagnosis. Renal infarcts usually present as wedge-shaped enhancement defect. Clinical context (e.g., pain in the absence of infection) and cortical rim enhancement through capsular collaterals are helpful.

Accessory spleen or splenosis (acquired usually after trauma or splenectomy) may simulate a renal mass.[5] Diagnostic clues include history of trauma and spleenectomy, multiplicity of lesions, and enhancement similar to spleen. Definite diagnosis is usually made with nuclear medicine scan, reticuloendothelial system-specific contrast agents, and/or biopsy.

RCC is the primary diagnostic consideration among primary renal neoplasms. A renal mass with enhancing soft tissue component is presumed to represent a RCC and is usually referred for surgical resection.[1]

Transitional cell carcinoma (TCC) is the second most common renal malignancy after RCC. Typically, it arises from the renal pelvis and spreads outwards in an infiltrating fashion without distorting the renal contour. On precontast CT, TCC is hyper dense to urine, and on postcontrast images it enhances less than adjacent renal parenchyma and RCC. It is visualized best on the nephrographic phase and it can be missed on the corticomedullary phase of enhancement.[1]

Oncocytoma is a benign asymptomatic lesion usually encountered in elderly men.6 It demonstrates a characteristic stellate scar in approximately one-third of the patients. Oncocytomas enhance after contrast administration and cannot be reliably distinguished from RCC on imaging; partial nephrectomy is usually required.

Angiomyolipomas (AML) are well known fat-containing lesions, and are usually sporadic or associated with tuberous sclerosis. In a small percentage of patients, AMLs lack macroscopic fat, which clinches the diagnosis and can be difficult to distinguish from RCC. Chemical shift MRI is used for identifying small amounts of fat within these lesions.[7]

Medullary carcinoma is an uncommon aggressive malignancy, almost exclusively encountered in young males with sickle trait. It arises from calyceal epithelium and infiltrates the kidney without distorting its contour. It enhances heterogeneously and typically less than normal renal tissue.[8]

Solitary fibrous tumors are fibrous neoplasms arising from serosal surfaces of organs, usually the pleura.[9] Malignant potential in the form of metastases or local recurrence has been described in 10-15% of cases. They present as lobulated exophytic masses arising from the region of the renal sinus or the capsule, and are indistinguishable from RCC. Surgical resection is the preferred treatment.

Renal metastases are seen in approximately 10% of patients with known primary tumor. The primary lesion is usually in the lung, colon, or breast.[10] Synchronous RCC is always a diagnostic consideration, necessitating tissue diagnosis.

Lymphomatous renal involvement occurs usually in the setting of widespread non-Hodgkins lymphoma; primary lymphoma is rare. The most common pattern of involvement is multiple bilateral renal masses followed by contiguous spread, diffuse infiltration, and solitary mass. Lymphoma is typically homogeneous and hypoechoic on ultrasound, and enhances less than the adjacent normal tissue on CT and MRI.[11]

Renal involvement in leukemia is common and usually infiltrative. Focal abnormalities can also occur, and the most common type is acute lymphoblastic leukemia.[12]

Renal plasmacytoma is rare. Typically renal involvement occurs in an infiltrating fashion in the setting of known of multiple myeloma or plasmacytoma involving other organs.[13]

Primary neuroectodermal tumors are rare highly aggressive neoplasms that carry a grave prognosis. Outside the CNS, PNETs can involve the chest wall, the paraspinal areas, and rarely organs, including the kidneys. Imaging characteristics in the kidneys include a heterogeneous large mass with minimal enhancement, hemorrhage, and metastases at presentation.[14] Tissue diagnosis is required.

Renal masses are common incidental findings on imaging. RCC is usually the main diagnostic consideration. However, familiarity with other common and less common renal lesions[15] is essential for improved diagnostic accuracy, and optimal management.[1]

References:

  1. Taneja R, Bhargava P, Cuevas C, et al. Common and less-common renal masses and masslike conditions. Radiol Clin North Am. 2012 Mar;50(2):245-57
  2. Hidalgo H, Dunnick NR, Rosenberg ER, et al. Parapelvic cysts: appearance on CT and sonography. AJR Am J Roentgenol 1982;138:667–71.
  3. Bhatt S, MacLennan G, Dogra V. Renal pseudotumors. AJR Am J Roentgenol 2007;188: 1380–7. Takahashi N, Kawashima A, Fletcher JG, et al.
  4. Takahashi N, Kawashima A, Fletcher JG, et al. Renal involvement in patients with autoimmune pancreatitis: CT and MR imaging findings. Radiology 2007; 242:791–801.
  5. Rahbar H, Bhargava P, Vaidya S, et al. Intrapancreatic accessory spleen. Radiology Case Reports. [Online] 2010;5:386.
  6. Quinn MJ, Hartman DS, Friedman AC, et al. Renal oncocytoma: new observations. Radiology 1984; 153:49–53.
  7. Kim JK, Kim SH, Jang YJ, et al. Renal angiomyolipoma with minimal fat: differentiation from other neoplasms at double-echo chemical shift FLASH MR imaging. Radiology 2006;239:174–80.
  8. Blitman NM, Berkenblit RG, Rozenblit AM, et al. Renal medullary carcinoma: CT and MRI features. AJR Am J Roentgenol 2005;185:268–72.
  9. Bhargava P, Lee JH, Gupta S, et al. Radiologic-pathologic findings of solitary fibrous tumor of the prostate presenting as a large mass with delayed filling-in on MRI. Radiology Case Reports. (Online) 2012;7:634.
  10. Choyke PL, White EM, Zeman RK, et al. Renal metastases: clinicopathologic and radiologic correlation. Radiology 1987;162:359–63.
  11. Sheth S, Ali S, Fishman E. Imaging of renal lymphoma: patterns of disease with pathologic correlation. Radiographics 2006;26:1151–68.
  12. Hilmes MA, Dillman JR, Mody RJ, et al. Pediatric renal leukemia: spectrum of CT imaging findings. Pediatr Radiol 2008;38:424–30.
  13. Dimopoulos MA, Kiamouris C, Moulopoulos LA. Solitary plasmacytoma of bone and extramedullary plasmacytoma. Hematol Oncol Clin North Am 1999;13:1249–57.
  14. Lee H, Cho JY, Kim SH, et al. Imaging findings of primitive neuroectodermal tumors of the kidney. J Comput Assist Tomogr 2009;33:882–6.
  15. Ghonge NP, Mittal D, Jain S, et al. Urologic manifestations of inflammatory pseudotumor: Report of 2 cases and review of the literature. Radiology Case Reports. (Online) 2012;7:742.

Written by:
Marinos Kontzialis, MD,[a] Manjiri Dighe, MD,[b] Chandana Lall, MD,[c] and Puneet Bhargava, MD[d]* as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.

  1. PGY-5 Resident in Diagnostic Radiology, The Ohio State University Wexner Medical Center
  2. Associate Professor, University of Washington Medical Center, Seattle WA
  3. Professor of Clinical Radiology, University of California, Irvine, Radiological Sciences
  4. *Corresponding Author
    Assistant Professor, University of Washington & VA Puget Sound Health Care System Mail Box 358280, S-114/Radiology, 1660 S Columbian Way, Seattle WA 98108-1597
    Email:

 

Common and less-common renal masses and masslike conditions - Abstract

More Information about Beyond the Abstract