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Abdomen » Kidneys/Ureters
Papillary renal carcinoma
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Presentation A 62 year old male was examined for right flank pain lasting for two weeks. Clinical and laboratory findings were normal. Chest radiography revealed a left pleural effusion and old tuberculous apical lesions bilaterally.
 
 
 
Caption: Transverse image of the lower third of the right kidney
Description: Right renal mass, with solid -looking, echogenic content (arrow: right kidney, T: tumor).
 
 
 
Caption: Transverse image of the lower third of the right kidney
Description: Nodular hypoechoic structure on the posterior wall of the right renal mass (RD: right kidney, T tumor, N: nodular structure)
 
 
 
Caption: Transverse image of the lower third of the right kidney
Description: Magnified image, same plane as image 2 (T: tumour, N: hypoechoic nodular structure).
 
 
 
Caption: Non-enchanced abdominal CT
Description: Fluid density mass of the right kidney. Intracystic papillary projections.
 
 
 
Caption: Postcontrast abdominal CT
Description: There is a slight increase of the density of the nodular structure on the wall of the right renal mass.
 
Differential Diagnosis
  • Papillary renal carcinoma

  • Hemorrhagic renal cyst

  • Renal abscess

  • Angiomyolipoma - Usually readily distinguishable from renal cell carcinoma by the finding on CT scan of a distinctive fat density that is less than that of water (-10 to -100 Hounsfield units).

  • Oncocytoma

  • Renal sarcoma

 
Final Diagnosis Papillary renal cell carcinoma
 
Discussion

Papillary renal cell carcinoma (PRCC) is a distinct subtype of renal cell carcinoma (RCC). It represents approximately 8-15% of all RCC. This tumor is often associated with chromosomal abnormalities. There are at least two types of PRCC. Type 1 is found in hereditary PRCC and is associated with a good long-term prognosis. Type 2 is found in hereditary leiomyoma RCC syndrome and is a more aggressive form of cancer than type 1 [1, 2,3,4,5,6].  PRCC are villous tumors, with vascularized stalks. Despite this, the tumors are hypovascular in appearance [5]. There is an increased risk of bladder and prostate cancer in this disease. Multifocality is also more often encountered in these patients [6].  There are no specific clinical signs in PRCC. Flank pain, hematuria and flank mass are encountered in advanced disease [1,2]. Our patient presented only right flank pain. 

Imaging is crucial in the detection, characterization and staging of PRCC. Ultrasonography provides accurate anatomic information on extrarenal extension of the tumor, adrenal or lymph node involvement, and invasion of neighboring viscera. US can be useful in evaluating questionable cystic renal lesions if CT imaging is inconclusive [1,2,7]. PRCC is characterised by its cystic appearance with thickened, irregular walls, "impure" fluid content and moderate acoustic enhancement [8].

The peculiarity of this case consists in the fact that the solid component of the cyst (the tumor itself) was less echogenic than the fluid surrounding it. This was due to recent intracystic hemorrhage.

On contrast-enhanced CT, PRCC appears generally hypovascular and enhances only 10-30 HU after intravenous administration of contrast material. Similarly, changes in signal intensity on MR images can be subtle (as low as 15% increase in signal intensity after contrast enhancement), reflecting the hypovascular nature of these tumors [1,2,7].

Herts et al suggested that a tumor characterized by a post contrast parenchyma-tumor density ratio over 25%, is unlikely to be a PRCC, and that a tumor with a low normal parenchyma-tumor or tumor-aorta ratio usually suggest a PRCC [9].

Surgical resection remains the only known effective treatment for localized PRCC, and it also is used for palliation in metastatic disease [10].
 
Case References
  1. Kush Sachdeva, Mansoor Javeed, Brendan Curti, Renal cell carcinoma; http://www.emedicine.com/med/topic2002.htm

  2. Hilton S. Imaging of renal cell carcinoma, Semin Oncol 2000; 27(2):150-9.

  3. Bastian PJ, Vogel J, Feldmann M, Bastian HP. Papillary renal cell carcinoma within the wall of a solitary renal cyst; Annales d'urologie 2003; 37:221-222.

  4. Lindor NM et all. Papillary Renal Cell Carcinoma: Analysis of Germline Mutations in the MET Proto-Oncogene in a Clinic-Based Population; Genetic Testing 2001; 5(2):101-106.

  5. Choyke PL, Glenn GM, McClellan MW, Zbar B, Linehan WM. Hereditary Renal Cancers; Radiology 2003; 226:33-46.

  6. Yorukoglu K, Aktas SM, Mungan U, Kirkali Z. Tubular dysplasia and carcinoma in situ: Precursors of renal cell carcinoma; Adult Urology 1999; 53(4):684-689.

  7. Israel GM, Bosniak MA. Calcification in Cystic Renal Masses: Is It Important in Diagnosis?; Radiology 2003; 226:47-52.

  8. Dudea SM, Rinichiul. In: Badea RI, Dudea SM, Mircea PA, Stamatian F. Tratat de Ultrasonografie Clinica, Editura Medicala, Bucuresti, 2000, 472-479.

  9. Herts BR et al. Enhancement Characteristics of Papillary Renal Neoplasms Revealed on Triphasic Helical CT of the Kidneys; AJR 2002; 178:367-372.

 
Technical Details The ultrasound examination was performed using a Medison SonoAce 6000 Color scanner with 3.5-5 MHz curved transducer.
 
Follow Up

CT examination revealed a 9 x 7 cm fluid-filled lesion, in the lower third of the right kidney. The lesion had a well-defined outline, thickened walls (0.8 cm) with papillary protrusions, and indented the liver without invading it (image 4). After contrast injection, a slight increase of density was seen in the nodular structure localized within the tumor (image 5). No abnormal lymph nodes or venous thrombi were seen.

Radical retroperitoneal nephrectomy was performed. The pathological diagnosis was renal cell carcinoma, papillary type with low-grade malignancy. The postsurgical evolution was unremarkable.

 

 
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