Case Author(s): Stephen Schmitter, M.D. and Farrokh Dehdashti, M.D. , 4/4/01 . Rating: #D3, #Q3

Diagnosis: Renal Cell Carcinoma

Brief history:

74 year-old man with abdominal pain.

Images:

Coronal FDG-PET Images

View main image(pt) in a separate image viewer

View second image(pt). Coronal, Axial and Sagittal FDG-PET Images Through the Area of Interest

View third image(ct). Selected Axial Computed Tomographic Images of the Abdomen

View fourth image(us). Longitudinal and Transverse Ultrasound Images of the Right Kidney

Full history/Diagnosis is available below

Diagnosis: Renal Cell Carcinoma

Full history:

74 year-old man with history of renal cell and prostate carcinoma both diagnosed 12 years ago. He underwent left nephrectomy and lymph node dissection, which demonstrated lymph node metastases from both of his primary malignancies. He also underwent orchiectomy and hormonal therapy. He did well until 2 weeks ago when he developed abdominal pain. Computed tomography and ultrasound revealed a right renal mass suspicious for malignancy. FDG-PET is requested for staging evaluation.

Radiopharmaceutical:

15.0 mCi F-18 Fluorodeoxyglucose intravenously

Findings:

Coronal FDG-PET images (main and second images) demonstrate surgical absence of the left kidney. Intense hypermetabolism is noted extending exophytically from the lower pole of the right kidney. Areas of decreased metabolism are present in both hepatic lobes, consistent with cysts.

Selected axial CT images (third image) show low attenuation lesions in the liver corresponding to areas of decreased metabolism, consistent with cysts. An exophytic low attenuation lesion is noted at the lower pole of the right kidney.

Longitudinal and transverse ultrasound images (fourth image)confirm a hyperechoic solid mass in the lower pole of the right kidney.

Discussion:

There is currently limited experience with FDG-PET and renal cell carcinoma (Ho et al., 1998). One study (Bachor et al., 1996) evaluating 29 patients with solid renal masses demonstrated a sensitivity of 77% (20 of 26 patients with renal cancer)and 3 false positives (angiomyolipoma, pericytoma and pheochromocytoma). In another 3 patients, FDG-PET detected regional nodal metastases.

A second study (Miyauchi et al., 1996) evaluating factors in the degree of FDG uptake in renal cell carcinoma (n = 11) demonstrated that patients with higher grade tumors had positive FDG-PET studies. The fact that many renal cell carcinomas are lower in grade may explain the relatively low sensitivity.

Another limitation with FDG-PET evaluation of renal cell carcinoma is the fact that FDG is excreted by the kidneys. Thus, variable degrees of increased uptake are normally seen in the renal parenchyma and collecting system, making detection of focal increased uptake in a tumor difficult. In this particular case, evaluation was simplified by the exophytic nature of the mass.

Reference: 1. Hoh CK et al., Positron Emission Tomography in Urological Oncology. J Urol. 1998;159(2):347-356.

2. Bachor et al., Positron Emission Tomography Diagnosis of renal cell carcinoma. Urology 1996; 35:146.

3. Miyauchi et al., Correlation between visualization of primary renal cancer by FDG-PET and histopathological findings. J Nucl Med (Suppl) 1966; 37:64.

Followup:

The patient underwent partial right nephrectomy, which revealed renal cell carcinoma, papillary type, Fuhrmann grade II-III/IV. Lymph nodes were free of tumor.

Major teaching point(s):

Although a positive FDG-PET is useful in evaluating renal cell cancer, a negative scan does not exclude this type of cancer.

ACR Codes and Keywords:

References and General Discussion of PET Tumor Imaging Studies (Anatomic field:Genitourinary System, Category:Neoplasm, Neoplastic-like condition)

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Case number: pt056

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