FDG PET in solitary metastastic/secondary tumor of the kidney: A report of three cases and a review of the relevant literature

FDG PET/CT in Solitary Isolated Renal Metastasis From Squamous Cell Lung Cancer

ABSTRACT

We describe FDG PET/CT findings in a patient with a solitary isolated renal metastasis from squamous cell lung cancer. The renal metastasis appeared as a small focus of activity at the renal cortex on FDG PET/CT at initial staging of the lung tumor, misinterpreted as cortical tracer retention, and was significantly enlarged on the second FDG PET/CT performed 4 months after the first PET/CT. This case demonstrates the usefulness of FDG PET/CT in identifying unexpected extrathoracic metastasis from lung cancer. Focal FDG uptake in the renal cortical region in a cancer patient should be evaluated carefully to avoid misdiagnosis.

FDG PET/CT in Unilateral Renal Metastasis From Colon Cancer

ABSTRACT

Renal metastasis from colon cancer is rare. We describe FDG PET/CT findings in a case with a right renal and a postcaval lymph node metastasis from colon cancer. Both the renal tumor and postcaval lymph node showed increased FDG uptake with SUVmax of 6.1 for the renal tumor and 5.5 for the postcaval lymph node. The imaging findings mimicked a primary renal cancer with postcaval lymph node metastasis.

Increased FDG Uptake on Juxtaglomerular Cell Tumor in the Left Kidney Mimicking Malignancy

Juxtaglomerular cell tumor is a rare and benign tumor arising from the juxtaglomerular apparatus that overproduces renin, resulting in secondary hypertension. A 29-year-old woman was incidentally found to have a left renal mass by ultrasonography in a routine health examination. Contrast-enhanced CT results suggested renal cell carcinoma. FDG PET/CT performed for metastatic workup showed increased FDG uptake to the left renal mass and did not reveal any other abnormal FDG-avid lesions. The renal mass was surgically resected and pathological examination confirmed the juxtaglomerular cell tumor of the left kidney.

FDG PET/CT in 2 Cases of Renal Metastasis From Esophageal Squamous Cell Carcinoma

Clinically, renal metastasis from esophageal squamous cell carcinoma is uncommon. We present 2 cases of renal metastasis from esophageal squamous cell carcinoma with enhanced CT and FDG PET/CT findings. In the first case, right kidney and right renal hilum were the only known metastatic sites. In the second case, bilateral kidneys were the only known metastatic sites. All the renal metastatic tumors appeared as hypovascular and hypoattenuating masses involving both the renal cortex and medulla on enhanced CT and intense FDG uptake on FDG PET/CT.

Renal Masses Detected on FDG PET/CT in Patients With Lymphoma: Imaging Features Differentiating Primary Renal Cell Carcinomas From Renal Lymphomatous Involvement

OBJECTIVE

The purpose of this study is to analyze the ¹⁸F-FDG PET/CT features of solid renal masses detected in patients with lymphoma and to evaluate the ability of PET/CT to differentiate renal cell carcinoma (RCC) from renal lymphomatous involvement.

MATERIALS AND METHODS

Thirty-six patients with solid renal masses on PET/CT performed for staging or follow-up of lymphoma were evaluated retrospectively. The features recorded for each renal mass included the following standardized uptake values (SUVs) on PET/CT: the maximum SUV (SUV_max), the mean SUV (SUV_mean), the ratio of the SUV_max of the tumor to that of the normal kidney cortex, the ratio of the SUV_mean of the tumor to that of the normal kidney cortex, the ratio of the SUV_max of the tumor to that of the normal liver, and the ratio of the SUVmean of the tumor to that of the normal liver. Renal mass size and margins (well defined vs infiltrative) and the presence of calcifications were evaluated on CT. Renal biopsy results were used as the reference standard. Relationships between imaging parameters and histopathologic findings were assessed.

RESULTS

Of the 36 renal masses evaluated, 22 (61.1%) were RCCs and 14 (38.9%) were renal lymphomas. All SUV metrics were higher for renal lymphomas than for RCCs (p < 0.0001, for all). All renal lymphomas had an SUV_max higher than 5.98 g/mL (median, 10.99 g/mL), whereas all RCCs had an SUV_max lower than 5.26 g/mL (median, 2.91 g/mL). No statistically significant differences in mass size or margins were found between RCCs and renal lymphoma.

CONCLUSION

PET/CT features may be useful for differentiating RCCs from renal involvement in patients with lymphoma with solid renal masses.

Diagnostic Challenges of Kidney Cancer: A Systematic Review of the Role of Positron Emission Tomography-Computerized Tomography

PURPOSE

Positron emission tomography-computerized tomography is a leading imaging modality for many types of solid tumors. The ability to characterize molecular processes noninvasively during a relatively fast whole-body scan is the major advantage of this technology. We reviewed the literature in an attempt to clarify the usefulness of positron emission tomography-computerized tomography in patients with a renal mass.

MATERIALS AND METHODS

We searched PubMed® for articles published from 2004 through September 2015 using the keywords "renal," "kidney," "mass," "tumor," "cancer," and "PET/CT."

RESULTS

A total of 158 relevant articles were included in the review. Most diagnostic studies used (18)F-fluorodeoxyglucose, a marker of glucose metabolism, as the radiotracer. The results were substandard, with sensitivity rates in the range of 31.5% to 77% for diagnosis of renal cell carcinomas. There were higher success rates for diagnosis of clear cell carcinomas. Carbonic anhydrase IX is an enzyme expressed in 95% of clear cell carcinomas but not in normal renal tissue or in benign or nonclear cell malignancies. A chimeric mouse-human antibody to carbonic anhydrase IX labeled with (124)I-girentuximab was demonstrated to diagnose clear cell tumors with sensitivity of 86.2% and specificity of 85.9%. For diagnosis of metastases positron emission tomography-computerized tomography with (18)F-fluorodeoxyglucose was observed to be more accurate than computerized tomography alone (94% vs 89%). Studies with other tracers also reveal encouraging results. Positron emission tomography-computerized tomography holds great promise in predicting prognosis and response to tyrosine kinase inhibitors. Current tyrosine kinase inhibitor treatments usually induce only mild lesion shrinkage. Thus, assessment of response based on changes in size of metastases is insufficient. Low (18)F-fluorodeoxyglucose uptake before treatment and decreased uptake after 2 cycles of treatment are associated with better survival. Using labeled medications as radiotracers before actual treatment may assist in selection of the most effective medication for a specific patient.

CONCLUSIONS

Positron emission tomography-computerized tomography with (18)F-fluorodeoxyglucose currently has lower sensitivity compared to enhanced computerized tomography for diagnosis of primary renal masses but better sensitivity for diagnosis of metastases. Predicting and monitoring response to targeted therapy could direct the clinician toward drug selection or modification during therapy. The possibility of treating patients with advanced renal cell carcinoma with (124)I-girentuximab attached to (177)Lu, a strong β-emitter, is investigated.

Secondary malignancies diagnosed using kidney needle core biopsies: a clinical and pathological study of 75 cases

Involvement of the kidney by secondary malignancies is uncommon. Differentiating secondary malignancies from primary kidney/urothelial tumors can be challenging, especially on limited biopsy material. A retrospective search of our institutional archive from January 2002 to May 2015 identified 1572 cases of imaging-guided needle core biopsies of the kidney. Of these, 75 (5%) cases revealed a secondary malignancy; 48 (64%) patients had undergone the biopsy with a primary kidney tumor favored clinically. There were 39 male and 36 female patients with a mean age of 59.4 years (range, 21-83 years). The majority of the cases (n = 55, 73%) were metastases from solid tumors, with lung being the most common primary site (n = 22, 29%). Diffuse large B-cell lymphoma was the most common hematological malignancy (n = 6) secondarily involving the kidney. Radiographically, 58 (77%) cases presented as a solitary kidney mass. The primary malignancy was known prior to the kidney biopsy in 66 (88%) cases. The mean interval between diagnoses of the primary tumor and secondary involvement of the kidney was 4.5 years. Immunohistochemical stains were performed in 65 (87%) cases. Follow-up information was available for 73 patients; mean survival was 19.4 months, with 43 patients dead of their disease (mean, 12 months) and 30 patients alive at last follow-up (21 with and 9 without disease; mean, 30 months). Secondary malignancy in the kidney may clinically and pathologically mimic primary kidney tumors. Accurate diagnosis can be rendered by correlating pathological features with clinical and radiographic findings and judicious use of ancillary studies.

Hematologic malignancies of the pancreas

Hematologic malignancies are relatively uncommon neoplasms of abdominal soft tissue. This article discusses the clinical and imaging features of pancreatic lymphoma, pancreatic extraosseous multiple myeloma, granulocytic sarcoma (chloroma), posttransplant lymphoproliferative disorder, and Castleman disease. The combination of imaging findings and the appropriate clinical presentation should allow the radiologist to raise a provisional diagnosis of hematologic malignancy.

Synchronous malignant renal mass in patient with a Lung cancer: case report and literature review

The finding on imaging (computed tomography scan or magnetic resonance imaging) of synchronous malignant renal mass in patient with an active nonrenal malignancy without renal specific symptoms is not frequent and diagnostic evaluation can be challenging. We describe a 54-year-old Moroccan male former chronic smoker who presented to our hospital with dry cough and impairment of the performance status. The imaging found a tumor mass in the left upper lobe of the lung associated to mediastinal lymph node and a scanno-guided biopsy of this tumor showed a non small cell lung cancer. The radiological staging revealed a solitary renal mass in the right kidney. The patient received firstly two cycles of a lung cancer chemotherapy with a partial response in the lung and a stability of the renal mass. Consequently, he underwent a scanno-guided biopsy of this mass which confirmed a synchronous clear cell renal carcinoma. The patient got chemo radiotherapy for the lung cancer and then after that he got a partial nephrectomy. He is still under a good control with more than 2 years after the initial diagnosis.

Benefit of a second opinion for lung cancer: no metastasis to the kidney but a synchronous primary renal neoplasm

Background

The finding of a renal mass on imaging is suggestive of metastatic non-small cell lung cancer in the presence of a lung tumor but can also have another origin.

Case Report

We describe the case of a patient diagnosed with stage IV lung cancer based on a renal metastasis. A second opinion including review of histopathological data and additional imaging followed by lung surgery and cryoablation of the kidney lesion revealed two tumors of different origins, non-small cell lung cancer and a renal cell carcinoma.

Discussion

The presence of a renal mass diagnosed on a CT scan in a patient with lung cancer is not always synonymous with metastatic disease. Confirmation of diagnosis by tissue sampling is mandatory, especially if a synchronous primary tumor is possible.

Can Initial (18)F-FDG PET-CT Imaging Give Information on Metastasis in Patients with Primary Renal Cell Carcinoma?

Purpose

The aim of this study was to investigate the relationship between the maximum standardized uptake values (SUVmax) of primary renal cancers with and without metastatic lesions, if any. We also studied the relationship between the size of primary renal cancers and their SUVmax, and tried to find a clinical value of ¹⁸F-FDG PET-CT for the initial evaluation of renal cell carcinoma (RCC).

Methods

The cases of 23 patients, 16 men and 7 women, who underwent PET-CT examination before operation were retrospectively reviewed. We measured the SUVmax of the primary renal cancers and those of any existing metastatic lesions, and the size of the primary renal cancers. We compared the SUVmax of primary RCCs with metastases and those without metastases, SUVmax of primary RCC and those of metastases, and studied the correlation between the size and SUVmax of primary RCCs.

Results

The SUVmax of primary RCC of the 16 patients without metastasis ranged from 1.1 to 5.6 with a median value of 2.6. Those of the patients with metastasis ranged from 2.9 to 7.6 with a median of 5.0. The size of the all 23 primary renal cancers ranged from 1.7 cm to 13.5 cm, with a median of 4.5 cm, and their SUVmax ranged from 1.1 to 7.6, with a median of 2.9. There was a statistically significant difference between the SUVmax of the primary RCC with metastasis (5.3 ± 1.7) and those without metastasis (2.9 ± 1.0). There was a moderate positive correlation between the sizes and SUVmax of all 23 primary RCCs. However, there was no statistically significant correlation between the sizes and SUVmax of primary RCCs with metastatic lesions and the same for RCCs without metastasis. The cutoff value of SUVmax for predicting extra-renal lesion was 4.4 and that for size was 5.8 cm according to the receiver operating characteristic curves.

Conclusions

Those who have primary RCC with high SUVmax are suggested to have a likelihood of metastasis. Also, there was a moderate trend of increasing value of SUVmax of primary RCC as their size increases. Physicians should beware of missing extra-renal lesions elsewhere.

Spectrum of malignant renal and urinary bladder tumors on 18F-FDG PET/CT: a pictorial essay

A wide variety of malignant renal and urinary bladder diseases can be detected on (18)F-FDG PET/CT. Although the PET/CT findings are often nonspecific, the aim of this atlas was to demonstrate that the spectrum of renal and urinary bladder malignancy that can be evaluated with PET/CT is much broader than current medical literature would suggest. PET/CT readers and oncologists should be aware of the variety of urological tumor types that can be detected on PET/CT and some of the patterns of (18)F-FDG uptake that can be observed in these cases.

Incidental Bilateral Renal Oncocytoma in a Patient with Metastatic Carcinoma of Unknown Primary: a Pitfall on (18)F-FDG PET/CT

Bilateral renal masses are uncommon but can raise a strong suspicion of primary or secondary malignancy, especially during the initial work-up of an oncology patient. Renal oncocytomas are benign renal tumors that are commonly discovered incidentally on diagnostic imaging with a small percentage occurring bilaterally. Although (18)F-FDG uptake in renal oncocytomas has been described, a case of a bilateral (18)F-FDG-avid renal oncocytoma has not been previously reported in the literature. A variety of malignant causes of bilateral (18)F-FDG positive renal masses are known, however it is important to include this benign etiology in the differential diagnosis. We report an unusual case of an incidental bilateral renal oncocytoma evaluated with contrast enhanced CT and (18)F-FDG PET/CT.

Role of FDG PET/CT in imaging of renal lesions

Focal incidental renal lesions are commonly encountered on positron emission tomography (PET)/computed tomography (CT) imaging. The vast majority of these lesions are benign. However, the interpretation of renal lesions can be problematic if the imaging criteria of simple cysts are not met. Limited literature exists on the characterisation of renal masses with metabolic imaging. The purpose of this article is to focus on the imaging features of benign and malignant renal masses with PET/CT. The lesions discussed include renal cyst, angiomyolipoma, oncocytoma, renal cell carcinoma, renal metastases and other infiltrating neoplastic processes affecting the kidney. Both the anatomical and metabolic features which characterise these benign and malignant entities are described. We emphasise the importance of viewing the CT component to identify the typical morphological features and discuss how to best use hybrid imaging for management of renal lesions. Metabolic imaging has a promising role in the imaging of renal lesions and can help prevent unnecessary biopsies and ensure optimal management of suspicious lesions.

Unusual involvement of scalp and bilateral kidneys in an aggressive mediastinal diffuse large B cell lymphoma: documentation by FDG-PET imaging

In the present communication, an unusual combination of scalp soft tissue and underlying brain involvement with intact skull bone coupled with bilateral renal involvement from a mediastinal diffuse large B cell lymphoma (DLBL) is presented. A 45-year-old man, a diagnosed case of mediastinal DLBL with bilateral lung involvement, was treated with conventional 6 cycles of chemotherapy and local external radiotherapy with initial good treatment response evidenced by considerable regression in mass size and regression in pulmonary lesions. Three months later, he returned with complaints of soft tissue swelling over the scalp; one of them in the high parietal bone and the other over the occipital region. A whole body FDG-PET at this time showed 2 moderate-sized foci in the scalp (with preservation of both tables of skull bone) and corresponding large foci in the brain parenchyma beneath, a superior mediastinal focus, a few foci in the apical and lower zone of left lung, extensive irregular uptake in the right pleura and the right lung parenchyma coupled with a loculated effusion in its lower zone and studded foci of hypermetabolism throughout the bilaterally enlarged kidneys. CT of the head confirmed the FDG-PET findings and histopathology of the biopsy from the scalp swelling was suggestive of DLBL. Ultrasound imaging of the abdomen showed lobulated bilaterally enlarged kidneys with multiple hypoechoic areas within them. The patient underwent palliative local external radiotherapy to the brain and systemic chemotherapy with poor clinical results with raised serum beta-2 microglobulin and serum LDH levels and deranged renal function. The patient died within a month after the FDG-PET study. The event of scalp and bilateral renal involvement from DLBL is rare in lymphoma literature and this report highlights that such unusual events can occur as part of widespread dissemination and underscores the importance of whole-body imaging with FDG-PET.

[PET-FDG in metastases from urological malignancies]

FDG-PET is useful for both topographic and metabolic analysis of metastatic cells. It uses a radioactive metabolite integrated into a molecule which penetrates into the tumoral cells. At present, concerning urologic carcinoma, there is no indication for its use in routine to diagnose primary tumors or to explore their development. However it can be useful for minor recurrences for which CT scan and MRI cannot be conclusive. In particular for kidney and urothelial carcinoma it may represent a diagnostic benefit. Nevertheless, interpretation is often made difficult by tracer urinary excretion. New radio tracers are being tested and will probably lead to new indications. Research on androgen receptors and molecular imaging is ongoing.

Recent advances in pediatric uroradiology

Pediatric Urology is a surgical subspecialty that is very dependent upon radiographic imaging as the majority of the genitourinary (GU) tract is internally located. Technological advances in various imaging modalities (e.g. ultrasonography, nuclear medicine, CT and MRI) have aided in our ability to visualize and evaluate the functionality of the GU tract, enabling the diagnosis of various disease processes that affect the genitourinary system. Collectively the advances in uro-radiology have improved our understanding of the natural history of many conditions that involve the GU tract. As a result of these newer imaging modalities, some of the more traditional techniques have assumed a limited role in the diagnostic evaluation of the pediatric GU patient (e.g. intravenous urography).The purpose of this article is to review the advances in radiographic imaging, in particular the cross-sectional imaging modalities and discuss their utility (appropriate indications and application) in Pediatric Urology, so that the reader can maximize the diagnostic yield of these studies. For a thorough review of any of the imaging modalities discussed in this article and their utility in the practice of pediatric urology, I would direct the readers to articles in the radiological literature that are specific to that technology. Besides the obvious technological advances in imaging modalities, this review also discusses the attention to radiation safety for the pediatric patient that every physician who orders a diagnostic imaging study in a child should be aware of.

[Lymphoma with initial renal involvement: four cases]

PURPOSE

To present a comprehensive description of the clinical features of patients with renal manifestations during lymphoma.

METHODS

Retrospective review of medical records from all patients diagnosed with lymphoma associated with kidney involvement in our hospital between 1996 to 2004. Four cases were identified and analysed.

RESULTS

Four patients presented a non-Hodgkin's lymphoma. One patient showed intravascular large B-cell lymphoma, revealed by proteinuria. Another patient had a nephrotic syndrome, and two had a renal mass. Renal histology allowed diagnosis of lymphoma in 3 cases.

CONCLUSION

The diagnosis of lymphoma associated with renal involvement is rather difficult, and more specifically in case of intravascular large B-cell lymphoma, or even primary renal lymphoma. We present here a comprehensive review of the literature and we discuss pathogenesis of these conditions.