Application of contrast-enhanced ultrasonography in the diagnosis of post-kidney transplant lymphoproliferative disorder in native kidney- a case report
Post-transplant lymphoproliferative disorders (PTLDs) represent a spectrum of heterogenetic lymphoid proliferations. PTLD is a serious complication that affects the long-term survival of kidney transplant patients. Imaging examination is an important method for detecting and diagnosing PTLD. Contrast-enhanced ultrasonography (CEUS) and CEUS-guided biopsy are important modalities for tumor detection and diagnosis. In this case, we describe a 69 years old man in whom a native kidney PTLD was confirmed by CEUS.
A 69-year-old male patient who had a kidney transplant 1 year earlier presented with 3 months of progressive myasthenia of both lower limbs associated with amyotrophy and weight loss. Although positron emission tomography/computed tomography (PET-CT) showed a high metabolic lesion in the untransplanted kidney, abdominal contrast enhanced computed tomography cannot detect the lesion in the atrophic left kidney. The above examinations showed that the transplanted kidney was normal. CEUS can detect a homogeneously enhanced lesion in the same location as PET-CT. Subsequently, a biopsy was performed under CEUS guidance, and the final pathological diagnosis was diffuse large B-cell lymphoma. The patient then received the R-CHOP treatment. Unfortunately, pulmonary thromboembolism occurred 2 weeks later, and the patient’s condition was not alleviated through active treatment. Finally, the patient’s family gave up treatment, and the patient was discharged.
The case suggested that CEUS was a valuable imaging method for patient with renal transplantation to detect and diagnose of PTLD.
KeywordsContrast-enhanced ultrasonography Biopsy Post transplantation lymphoproliferative Kidney transplantation
Contrast-enhanced computed tomography
Magnetic resonance imaging
Diffuse large B-cell lymphoma
Positron emission tomography/computed tomography
Post-transplant lymphoproliferative disorders
Post-transplant lymphoproliferative disorders (PTLDs) represent a group of heterogenetic lymphoid proliferations ranging from polyclonal lymphoid proliferation to lymphomas. PTLD occurs after solid organ transplantation and is associated with administration of immunosuppressive agents . Prompt diagnosis of PTLD is critical to prognosis, to prevent the further development of malignant lymphoma . Imaging examination is an important method to detect and diagnose PTLD, including conventional ultrasonography (US), Doppler ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI). Contrast-enhanced computed tomography (CE-CT) and contrast-enhanced magnetic resonance imaging (CE-MRI) are important image modalities for characterizing PTLD [3, 4]. However both the iodinated contrast agent for CE-CT and the gadolinium for MRI have potentially nephrotoxic, restricting their use in patients with impaired renal function . Compared with CE-MRI and CE-CT, the contrast agents used for contrast-enhanced ultrasonography (CEUS) are no nephrotoxic and can be safety applied to patients with renal dysfunction. CEUS can also provide real-time visualization of contrast-enhanced patterns, which can be used for differential diagnosis of renal lesions . In addition, the exact real-time aspect of CEUS makes it uniquely suited for interventions . CEUS therefore has gradually become the preferred method to detect and diagnose renal tumors in chronic kidney disease and post-transplant patients in recent years [8, 9]. We report a case of a 69 year old man with a native renal lymphoma associated with PTLD. We describe the contrast-enhanced features of the tumor and the application of a CEUS guided biopsy on the tumor, which is not well visualized using US. To the best of our knowledge this is the first report on CEUS manifestations of native renal lymphoma following renal transplantation.
Discussion and conclusions
The incidence of PTLD in kidney transplant patients is approximately 1–10%, and it occurs most frequently during the first year after transplantation. Immunosuppression and EBV infection, are two major factors associated with the progression of PTLD  .The Gastrointestinal tract, allograft kidney and abdominal cavity are common sites of PTLD, but it is rare in the native kidney, which has been described in only three studies [10, 11, 12]. In previous reports, both US and CE-CT can clearly show the tumor and be used to characterize the tumor. The tumors showed persistent hypo-enhancement throughout the examination with CE-CT. The enhancement pattern of the tumor is the main difference from clear cell renal cell carcinoma, which present avid early hyper-enhancement and early wash-out throughout the examination [13, 14].
In our case, the tumor showed avid early hyper enhancement on CEUS; however, this was not visible on US and CE-CT. There are three possible explanations for this difference in our case: First, since the microvasculature of the atrophic renal parenchyma was reduced compared to a normal kidney, less iodine contrast agent entered the renal parenchyma . In addition, the tumor was small in size, and there was much less iodine contrast agent entering the tumor. As a result, the tumor presented no enhancement on CE-CT, which caused a failure to distinguish tumors from surrounding cysts. Second, because CEUS contrast material is purely intravascular, it better correlates with the microvessel density of a tumor. Therefore, CEUS is even more sensitive for detection of hypovascular lesions than contrast-enhanced CT . Although the native kidney perfusion reduced in our case, the microvascular density of the tumor is relatively more abundant than the peripheral renal parenchyma. As a result, the tumor appeared hyper enhanced compare to the surrounding renal parenchyma on CEUS. Third, the CE-CT scan often started at 35 s after the beginning of the injection, but the lesion showed peak enhancement at 33 s during CEUS examination. This may result in missing the peak enhancement phase of the tumor on CE-CT. In contrast, real-time CEUS can continually provide information about blood perfusion for the renal lesion after injection, which can offer more diagnostic clues to differential the tumor from adjacent cysts.
US-guided biopsy is a common clinical method to obtain tissue specimens for histopathological analysis . However, this technique may be unsuccessful when the tumor is poorly differentiated from adjacent structures. CEUS is well placed to address this problem because of its capacity to differentiate between the altered vascularization of a tumor and surrounding structures. CEUS could help further confirm the tumor border and guide the needle to the target area. CEUS also can be used to differentiate enhanced active area from non-enhanced necrotic area. By directing the biopsy needle toward enhanced areas of the lesion, the sample from necrotic parts of the lesion can be reduced . In a previous report, using the contrast agent, the lesion detection rate was increased from 77.3% with US to 92.0% with CEUS during the biopsy, with a 95.2% success rate for CEUS-guided biopsies of these lesions [18, 19]. According to these finding, we performed the biopsy in our patient under the guidance of CEUS. Finally, the pathology of the biopsy specimen confirmed the diagnosis of diffuse large B cell lymphoma.
In summary, CEUS can provide more useful information than CE-CT to detect and diagnose PTLDs derived from atrophic native kidneys; CEUS-guided biopsy can improve the diagnostic accuracy and success rate of percutaneous biopsy. We believe that CEUS and CEUS-guided biopsy may be an effective method for early screening and diagnosis of native kidney PTLD in kidney transplant patients.
Our report described the imaging feature of native kidney lymphoma on contrast-enhanced ultrasonography (CEUS) in a post-kidney transplant patient. We found that the lymphoma showed different enhanced pattern in atrophic kidney from the normal kidney. Then, we performed the tumor biopsy under the guidance of CEUS
Publication of clinical datasets
JCZ design the study and drafting of the manuscript; HXL, HJZ, YYL acquisition the data and images; LM designed and generated all of the submitted Figs; XYX and MDL analysis the data and images; WW interacted with the patient; made substantial contributions to the content and design of the study; critical revision of the manuscript and take accountable for all aspects of the work to ensure the reliability and accuracy of the data. All authors and all authors have made significant contribution to the content of this paper. All authors read and approved the final manuscript.
Our work is supported by National Natural Science Foundation of China (No.81701701) (to W.W), Natural Science Foundation of Guangdong Province (No.2016A030310143) (to W.W) and Department of Finance of Guangdong Province (No.20160904) (to W.W). All of the above funding was used to conduct laboratory analyses and cover publication fees.
Ethics approval and consent to participate
Consent for publication
The patient provided written informed consent to publish this report and associated images. We have de-identified demographic information and other specific information of the patient.
Our manuscript has been read and approved by all authors and there are no any financial or other interests in the subject matter of the manuscript.
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