1. Case Report Submitted by: Chad Lonsford, senior medical student
Radiological Category:
Genitourinary
Principal Modality (1):
Principal Modality (2): CT
none
Case Report
Submitted by:
Chad Lonsford, senior medical student
Faculty reviewer: Sandra A. A. Oldham, MD
Date accepted:
29 August 2007

2. Case History
55 year-old Caucasian female s/p D&C incidentally found to have elevated liver function enzymes. An abnormality was identified on ultrasound examination performed to evaluate her liver. Subsequently, a CT scan was ordered for further evaluation.

3. Early Phase Intravenous and Rectal Contrast CT
Radiological Presentations
Early Phase Intravenous and Rectal Contrast CT

4. Radiological Presentations

5. Radiological Presentations

6. Radiological Presentations

7. Radiological Presentations

8. Radiological Presentations

9. Late Phase Intravenous and Rectal Contrast CT
Radiological Presentations
Late Phase Intravenous and Rectal Contrast CT

10. Reformatted Coronal CT
Radiological Presentations
Reformatted Coronal CT

11. Radiological Presentations

12. Reformatted Sagittal CT
Radiological Presentations
Reformatted Sagittal CT

13. Test Your Diagnosis
Which one of the following is your choice for the appropriate diagnosis? After your selection, go to next page.
Simple Renal Cysts / Polycystic Kidney Disease (PCKD)
Renal Abscess
Angiomyolipoma
Renal Cell Carcinoma
Transitional Cell Carcinoma of the Renal Pelvis
Renal Lymphoma

14. Findings and Differentials
There is a 5.7 x 3.9 x 7.2 cm mass arising from the anterior mid to lower pole of the right kidney. The mass is predominantly cystic with punctuate calcifications and areas of enhancement in the lower portions. Gerota’s fascia is intact and there is no evidence of invasion of the IVC or adrenal glands. Additionally, there is a 2.2 x 1.4 x 3.1 cm parapelvic cyst within the left kidney in the lower pole.
Differentials:
Simple Renal Cysts / Polycystic Kidney Disease (PCKD)
Renal Abscess
Angiomyolipoma
Renal Cell Carcinoma
Transitional Cell Carcinoma of the Renal Pelvis
Renal Lymphoma

15. Discussion
A large irregularly marginated, heterogenous lesion with evidence of thick septation, hemorrhage, necrosis, or calcification is most likely renal cell carcinoma until proven otherwise. Further evidence for renal cell carcinoma is mild post-IV contrast enhancement of the lesion.
Simple renal cysts are very common and have precise borders without a perceptible wall. They are homogenously fluid-filled with attenuation near water density. Additionally, there is no evidence of enhancement after IV contrast administration. A complicated cyst can demonstrate hemorrhage, infection, or septation, however the septae are thin-walled, smooth, and regular.
Polycystic kidney disease consists of a positive family history, multiple bilateral renal cysts, and enlargement of the kidneys often with additional cysts in the liver or pancreas.

16. Discussion
A renal abscess will frequently appear as thick-walled, low-density fluid collections with gas sometimes seen within the pus. It is associated with signs of inflammation in adjacent tissue such as fat stranding and thickening of the renal fascia. The wall may enhance after IV contrast administration.
Angiomyolipomas are benign tumors consisting of blood vessels, smooth muscle, and fat. They are usually found as a solitary lesion in middle-aged women and is an important consideration in this case given the history. Whorls of soft-tissue are mixed with fat density and the demonstration of these fatty areas of tumor with attenuation values of -30 to -120 is diagnostic.

17. Discussion
Transitional cell carcinoma is characteristically identified as a soft tissue filling defect in the renal pelvis. Enhancement is poor and calcifications are rare. It is often seen compressing the adjacent collecting structures and tends to infiltrate the kidney rather than form a focal renal mass that is so typical with renal cell carcinoma.
Renal lymphoma may present as multiple parenchymal nodules, a solitary solid mass, or diffuse infiltration enlarging the kidney. Lymphoma typically is homogenous and enhances minimally. Other signs suggesting lymphoma include bilaterality, extensive adenopathy, and splenomegaly.

18. Discussion
Eighty percent of solid renal masses in adults are due to renal cell carcinoma. Males are affected more than females 2:1 and the average age of occurrence is between the fifth and sixth decade.
Characteristics of renal cell carcinoma include a hypodense or isodense lesion on precontrast CT while post-IV contrast CT demonstrates enhancement. It is typically heterogenous with thick walls and irregular margins. Ten to twenty percent of patients will have calcifications. Evaluation for renal vein or IVC invasion is mandatory for staging.
Renal cell carcinoma can be cystic as well. However in contrast to simple cysts, it often has multiple septations that are thick and enhancing and frequently contains enhancing soft-tissue elements.

19. Discussion
The Bosniak classification system is useful for categorizing renal masses.
Bosniak I – simple cysts with no enhancement, no visible wall, no internal
architecture, and clear fluid densities; no follow up needed
Bosniak II – no enhancement, a few fine septa, thin rim calcification, and fluid
densities; <5% malignant, no follow up needed
Bosniak IIF – <1.5 cm high-density lesions, wall cannot be identified; usually in the
cortex in young patients and are very difficult to diagnose; follow up
needed every 6 months x 2 yrs to assess for growth
Bosniak III – thick septations, visible enhancing wall, coarse calcifications, and
areas of enhancement >15 HU; 40-60% malignant
Bosniak IV – cystic masses with a solid wall nodule and enhancement >15 HU;
85-100% malignant; almost always renal cell carcinoma

20. Discussion 5 yr Survival
Surgery is the only effective therapy for renal cell carcinoma, therefore pre-operative CT staging is extremely important.
If distant metastases are not present, a nephrectomy is indicated, even if there is invasion of the renal vein or IVC (Stage III). Radiation and chemotherapy have a limited role in the treatment of renal cell carcinoma.
Robson Staging System for Renal Cell Carcinoma
Stage I Confined to the renal capsule
Stage II Extends through renal capsule but contained by Gerota’s fascia
Stage III Invades renal vein/IVC or has metastasized to local lymph nodes
Stage IV Invades adjacent organs or has distant metastases
5 yr Survival
Stage I %
Stage II %
Stage II %
Stage IV %

21. Discussion The patient underwent a laparoscopic right nephrectomy.
The specimen was sent to pathology and confirmed renal cell carcinoma, clear cell type without lymphovascular or ureteral invasion.
The patient in this case could be a manifestation of an uncommon condition known as Stauffer syndrome. Stauffer syndrome describes the renal cell carcinoma patient with no detectable metastatic disease who has hepatic dysfunction and elevated liver function tests. This disorder is considered a paraneoplastic syndrome and is related to cholestasis. Hepatic symptoms frequently resolve with removal of the primary renal cell carcinoma.

22. Stage II Renal Cell Carcinoma, clear cell type.
Diagnosis
Stage II Renal Cell Carcinoma, clear cell type.

23. References
Bennet, WM et al. Simple and complex renal cysts in adults. Up-To-Date. April Fielding, JR. CTA of renal cystic masses. Applied Radiology 2005; Online Supplement; Grey ML, Ailinani, JM. CT & MRI Pathology: A Pocket Atlas. New York, NY: McGraw Hill, 2003: Hartman DS, Davis CJ, Sanders RC et al. The multiloculated renal mass: Considerations and differential features. RadioGraphics 1987; 7: Israel GM, Bosniak MA. How I do it: Evaluating Renal Masses. Radiology 2005; 236: Kasper DL, Braunwald E, Fauci AS, et al. Harrison’s Principles of Internal Medicine, 16th Ed. New York, NY: McGraw Hill, 2005: Novelline RA. Squire’s Fundamentals of Radiology, 6th Ed. Cambridge, MA: Harvard University Press, 2004: Webb WR, Brant WE, and Helms CA. Fundamental of Body CT, 2nd Ed. Philadelphia, PA: W.B. Saunders Company, 1998: