Is The Value of FDG PET/CT in Evaluating Renal Metastasis Underestimated? A Case Report and Review of The Literature

Abstract

Contrast-enhanced CT or MRI are used as a gold standard imaging modalities in the detection and characterization of renal masses. On the other hand, the role of FDG PET/CT in evaluating primary or metastatic cancers of the kidney is limited due to the excretion of FDG through urinary tract. We reported the FDG PET/CT of a lung cancer patient with multiple metastases in both kidneys which were missed in previous PET/CT, and underestimated on sequential diagnostic abdominal CT study.Conflict of interest:None declared.

The Renal Sinus—Transitional Cell Carcinoma and its Mimickers on Computed Tomography

“…10 The most common CT appearance of renal metastases is bilateral, multifocal, small (< 3 cm), hypodense masses.…”

“…A renal metastasis is the most common malignant neoplasm of the kidney found at autopsy. 10 The most common primary sites for renal metastases (except hematologic malignancies) are lung, colon and breast carcinoma, melanoma and reproductive system malignancies. 10,11 Spread of metastasis to the kidney is usually hematogenous or lymphatic.…”

Secondary Tumors of the Kidney: A Comprehensive Clinicopathologic Analysis

“…42 Fluorine-18 fluorodeoxyglucose ( 18 F-FDG) PET/CT is extensively used in oncology, but its utilization in evaluating primary or metastatic involvement of the kidney is limited because physiological excretion of 18 F-FDG through the urinary tract may interfere with tumor imaging. 37 The most common CT appearance of renal metastases are bilateral, multifocal, small (< 3 cm), hypodense masses that do not commonly demonstrate hyperenhancement after contrast injection. 37,152 However, a solitary lesion, necrosis, hyperenhancement after intravenous contrast injection, renal vein thrombosis, and well-defined tumor margins usually support the diagnosis of renal cell carcinoma.…”

“…37,154 18 F-FDG PET is specific in the diagnosis of renal masses, but its sensitivity depends on the size and location of the lesion. 37,155 Due to the excreted radiopharmaceutical in the pelvicalyceal system and the lesions that do not accumulate 18 F-FDG, the sensitivity and specificity of 18 F-FDG PET/CT in detecting renal tumors are 60% and 100%, respectively. 37,156 Both iodine-131 ( 131 I) scan and 18 F-FDG PET/CT scan can play an important role in the diagnosis of metastatic thyroid carcinoma.…”

PET/Computed Tomography in Renal, Bladder, and Testicular Cancer

“…Occasionally a FDG PET scan performed for another malignancy will reveal a lesion within the kidney. It is uncertain whether this lesion represents a metastasis or another primary tumor 5 . Unfortunately, uptake in the lesion is not specific in this regard, and a biopsy is usually performed to clarify this dilemma.…”