A 51-year-old female is currently being evaluated for an incidentally detected right kidney mass. Patient underwent ¹⁸F-FDG PET/CT imaging before undergoing an operation.

Low level of FDG uptake at the lesion was suggestive of a benign lesion.

Histopathological evaluation after operation revealed renal cell carcinoma (RCC).

PET should have limited role in the characterization of primary renal tumors with its low sensitivity found as 62 % in a metaanalysis.

A 59-year-old female is currently being evaluated for a mass lesion at left kidney detected on USG. The patient was scheduled for operation and meanwhile she underwent ¹⁸F-FDG PET/CT imaging.

The lesion was suspicious for malignancy with its moderate FDG uptake.

After operation the lesion turned out to be an oncocytoma.

The pooled specificity of ¹⁸F-FDG PET/CT is found to be 88 % in the determination of malignant nature of kidney masses in a metaanalysis. Besides oncocytoma, there are several other benign lesions causing false positive FDG uptake like renal angiomyolipoma, renal pericytoma, nephroblastoma, renal tuberculosis, and xanthogranulomatous nephritis.

A 52-year-old female with a mass lesion originating from left kidney underwent ¹⁸ F-FDG PET/CT imaging.

Malignant lesion originating from left kidney and showing invasion to left renal vein.

The patient underwent operation and histopathology revealed RCC invading left renal vein.

¹⁸F-FDG PET/CT localizes RCC more efficiently in larger masses. One study showed an increase in sensitivity of FDG PET/CT from 76 to 92.9 % when the lesion size increased from more than 1–2 cm. RCC has a propensity to invade the venous system, with extension into the renal vein.

A 52-year-old female suffering from weakness, weight loss, right-sided flank pain, and hematuria for 2 months. When she consulted with these symptoms, tenderness in the right flank region and hepatomegaly was detected on physical examination. The patient underwent CT scan with iv contrast, and besides the mass lesion at right kidney, a filling defect in IVC extending to the right atrium, which was strongly suggestive of tumor thrombus was detected. ¹⁸F-FDG-PET/CT scan was performed in order to make metabolic characterization of the right renal mass together with the thrombus in IVC.

FDG avid malignant lesion originating from right kidney and intensely hypermetabolic tumor thrombus in IVC extending into right atrium.

The patient underwent right nephrectomy and biopsy was obtained from tumor thrombus in the IVC. The histopathology of the mass from the right kidney and thrombus in the IVC revealed RCC.

RCC has a propensity to invade IVC occurring in 4–10 % of all patients with RCC. Among these patients, 2–16 % have tumors extending into the right atrium.

A 52-year-old male who has a history of renal cell carcinoma status post left nephrectomy and chemotherapy suffered from intermittent episodes of epistaxis and sinusitis. The patient underwent nasal endoscopy that diagnosed a tumor in the left maxillary sinus and biopsy was performed. Further evaluation with ¹⁸F-FDG PET/CT imaging was done to determine the extent of metastatic disease.

Metastatic lesion at left maxillary sinus and left nasal cavity.

The biopsy from left maxillary sinus showed clear cell carcinoma

Paranasal sinuses are rare metastatic sites for RCC, but the most frequent primary tumor that metastasizes to paranasal sinuses is the RCC. Approximately 50 cases of nasal recurrences of RCC have been reported in the literature. Tumor involvement of the paranasal sinuses and nasal cavity seems to occur via the hematogenous route through the Batson’s paravertebral venous plexus.

A 60-year-old male underwent ¹⁸F-FDG PET/CT imaging while he was being evaluated for the mass lesion at proximal diaphysis of left humerus.

Mass lesion at left kidney was suspicious for malignancy. The hypermetabolism at left proximal humerus, right femur, and right iliac bone was indicating likelihood for metastases.

Biopsy of left humerus lesion revealed giant cell tumor of bone. Patient underwent left nephrectomy and histopathology was RCC.

One study reported that among all metastatic sites, ¹⁸ F-FDG PET/CT is most sensitive for bone metastases of RCC. PET is superior to bone scan in detecting active osseous metastasis of RCC. Sensitivity and specificity ¹⁸ F-18 FDG PET/CT reaches up to 100 % for the detection of bone metastases of RCC but there may be false positive findings like benign tumors of bone as in this case.

A 62-year-old male underwent ¹⁸F-FDG PET/CT imaging upon detection of a mass lesion at left kidney with anatomical imaging methods.