NDT Plus Advance Access originally published online on September 27, 2008
NDT Plus 2008 1(6):469-470; doi:10.1093/ndtplus/sfn153
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Contrast-enhanced ultrasonography with microbubbles for successful screening of kidney tumours
1 Renal Unit, Ghent University Hospital
2 Goormaghtigh Institute of Pathology, Ghent University Hospital
3 Department Sonography, Ghent University Hospital, Ghent Belgium
Correspondence: E-mail: katrien_de_wilde{at}hotmail.com
Sir,
A 70-year-old female had developed chronic kidney disease (CKD) stage 5 due to autosomal dominant polycystic kidney disease (ADPKD), for which she performed peritoneal dialysis for 1 year until her kidney transplantation.
On clinical evaluation, the patient mentioned a weight loss of 2 kg in the last 6 months but with normal appetite and without asthenia. Medical examination revealed the absence of fever and no lymphadenopathies. The polycystic liver and both native polycystic kidneys were enlarged on abdominal palpation, but with no obvious change in volume versus previous check-ups. The chest X-ray, cardiac echography and dermatological and gynaecological examinations were normal.
The abdominal ultrasonography revealed nodular lesions in both native polycystic kidneys, which had not been visualized before, of 1.4 cm diameter in the right and 2 cm diameter in the left kidney. Colour Doppler and power Doppler could not demonstrate arterial flow in these nodules. However, a contrast-enhanced ultrasonography (CEUS) with the use of Sono-Vue® (BR1, Bracco, Milan, Italy), a contrast agent generating microbubbles by mixing with saline solution, showed vascularization in both lesions, suggesting solid vascularized tumours (Figure 1). Ultrasound-guided fine needle punctures of both lesions were performed. The cytology of the suspected mass in the right kidney was considered normal. The puncture of the left nodular lesion revealed papillary cells with nuclear atypia, suggesting a neoplasm.
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Shortly thereafter, a surgical resection of the left kidney was performed. Histopathology confirmed the diagnosis of polycystic kidney disease with the presence of a subcapsular nodule, revealing a renal cell carcinoma (RCC), Fuhrman grade 3. Further staging with head and chest CT scan, bone scintigraphy and contrast-enhanced abdominal CT scan did not demonstrate metastases. The RCC was staged as a pT1a/N0/M0, compatible with stage 1 disease. The post-operative follow-up was uneventful, and a 36-month post-operative check-up excluded tumour relapse.
RCC is an infrequent complication of ADPKD. An increased incidence as compared to the general population has not clearly been demonstrated, but the disease seems to have different and more aggressive characteristics in ADPKD [1].
In general, diagnosing RCC in ADPKD is difficult and often delayed, partially because of the cystic nature of ADPKD itself. Moreover, typical symptoms for RCC such as fever, flank pain and haematuria are frequently observed in ADPKD due to other complications, like lithiasis, mass effect, cyst bleeding or cyst infection [1]. The patient in the presented case did not have any complaints or clinical aberrations, except for a moderate weight loss. The diagnosis was suspected on an ultrasound examination, confirmed by CEUS and histologically proven after an ultrasound-guided puncture.
In complicated cystic renal lesions, the most important clue in differentiation between benignant and malignant cysts is the presence or absence of contrast enhancement with CT or MR imaging. Although ultrasonography can easily demonstrate fine septation, irregular wall thickening or the presence of a small mural nodule, its role has been limited owing to the inability to provide contrast enhancement. This major drawback is being overcome by recent advances in Doppler technology and the introduction of sonographic contrast agents [2].
CEUS can easily differentiate cystic lesions from solid lesions and suggests a solid tumour when showing hypervascularization [2]. It was demonstrated that CEUS allowed the most optimal visualization of tumour vascularization and a high diagnostic accuracy in differentiating between benign and malignant cystic lesions, compared with contrast-enhanced CT scan and MRI. CEUS showed 100% positive predictive value for benign cysts. Also a higher negative predictive value was demonstrated for CEUS, pointing out that patients could be spared additional CT-scanning or MRI [2].
CEUS is a valuable and safe alternative in the case of contra-indication for contrast-enhanced CT scan or MRI with gadolinium. Ultrasonographic contrast agents exhibit an excellent safety profile with no specific hepatic, renal or cerebral toxicity. No allergic reactions have been reported [3]. The iodium-containing contrast used for CT scan is deleterious in the case of contrast allergy, hyperthyroidism or risk of contrast nephropathy [4]. Because of the use of ionizing radiation, CT scan increases the risk for developing cancer. MRI is contra-indicated in patients having a pacemaker or internal defibrillator. In patients with renal failure, the contrast agent used during MR imaging, gadolinium, was recently associated with nephrogenic systemic fibrosis (NSF), a serious and irreversible disease characterized by a painful thickened skin [5]. The United States Food and Drug Administration (FDA) advises avoidance of gadolinium in patients with advanced renal failure (GFR <15 mL/min) and prudence in the case of moderate renal failure (GFR <30 mL/min). All these drawbacks can be obviated by the performance of CEUS, an interesting option especially in patients with CKD.
In conclusion, CEUS is a valuable, safe and easy tool in the diagnosis of vascularized lesions, such as kidney tumours in ADPKD patients.
Conflict of interest statement. None declared.
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[Free Full Text] - Grobner T. Gadolinium-a specific trigger for the development of nephrogenic fibrosing dermopathy and nephrogenic systemic fibrosis? Nephrol Dial Transplant (2006) 21:1104–1108.
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