Renal lymphoma: CT patterns with emphasis on helical CT

Renomegaly and acute kidney injury as primary manifestations of non-Hodgkin's lymphoma: a report of three cases

BACKGROUND

In adults with non-Hodgkin's lymphoma, renal enlargement and acute kidney injury occur infrequently at first presentation, especially in T lymphocytic lymphomas.

CASE PRESENTATION

We report three cases of non-Hodgkin's lymphoma with acute renal injury and bilateral renal enlargement. At diagnosis, one patient presented with an adrenal mass, one patient's lymph node biopsy was consistent with a renal biopsy, and one patient had primary renal lymphoma with no extrarenal disease. Assessment of renal pathology in Case 2 and Case 3 showed interstitial lymphocyte infiltration; the pathological types were non-Hodgkin's diffuse large B lymphoma originating from activated B cells outside germinal centers and non-Hodgkin's T-lymphoblastic lymphoma/leukemia, respectively. Case 1 did not receive anti-lymphoma therapy and died from infection and multiple organ failure within 1 month of hospitalization. Case 2 received eight courses of R-CHOP; her lymphoma recurred 2 years after diagnosis and she died from severe pulmonary infection 3 years after diagnosis. Case 3 received hyper-CVAD regularly and achieved stable renal function; this patient remains under follow-up.

CONCLUSIONS

Renal lymphoma may have diverse manifestations, especially primary renal lymphoma without extrarenal involvement. Nephrologists should pay careful attention to these manifestations to ensure accurate diagnosis.

Multimodality imaging of renal lymphoma and its mimics

Lymphomatous involvement of the genitourinary system, particularly the kidneys, is commonly detected on autopsies; yet on conventional diagnostic imaging renal lymphoma is significantly underestimated and underreported, in part due to its variable imaging appearance and overlapping features with other conditions. We present a spectrum of typical and atypical appearances of renal lymphoma using multimodality imaging, while reviewing the roles of imaging in the detection, diagnosis, staging, and surveillance of patients with lymphoma. We also illustrate a breadth of benign and malignant entities with similar imaging features confounding the diagnosis of renal lymphoma, emphasizing the role of percutaneous image-guided biopsy. Understanding the spectrum of appearances of renal lymphoma and recognizing the overlapping entities will help radiologists improve diagnostic confidence and accuracy.

Rosai-Dorfman disease: A case report of asymptomatic isolated renal involvement

A possible diagnosis of RDD should be kept in mind when encountering a patient with raised plasma creatinine levels and renal mass. Timely diagnosis and management of RDD will help prevent future kidney loss.

A rare case of bilateral primary renal Burkitt lymphoma presenting with acute renal failure

Acute renal failure due to primary renal Burkitt lymphoma in children is extremely rare. We report a case with acute secondary renal failure in a 4-year-old boy who presented with abdominal pain, anorexia, and vomiting. Abdominal computed tomography scans showed bilateral nephromegaly with multiple hypoenhancing regions. Renal biopsy confirmed Burkitt lymphoma. There was no lymphadenopathy or evidence of other solid organ involvement. The patient was responsive to treatment using the EPOCH-R protocol (etoposide, prednisone, vincristine, cyclophosphamide , doxorubicin, and rituximab). Here, we describe the clinical and imaging features associated with this rare entity.

Granulomatosis with polyangiitis presenting as a solitary renal mass: A case report with imaging and literature review

Granulomatosis with polyangiitis (GPA) manifests as necrotizing granulomatous inflammatory masses in the nasal cavity, paranasal sinuses, and lungs. However, a mass in the kidney is extremely rare. We herein report a case of GPA that presented as a solitary mass in the left kidney. The patient was a man in his 60s. A 2.5-cm solitary mass was incidentally discovered in the left kidney at another hospital and was followed-up. Eight months later, the mass had enlarged, and the patient visited our hospital for further examination and treatment. The mass was hypovascular, with unclear margins on contrast-enhanced computed tomography (CT). The signal of the mass was nonuniform and iso- to slightly hypo-intense on T2-weighted and diffusion-weighted magnetic resonance imaging (MRI). Enlarged para-aortic lymph nodes were also detected on the CT and MRI. Based on imaging, malignant tumors were suspected, and nephrectomy was performed. The pathological diagnosis was GPA. We performed a literature review of this rare renal manifestation and present a summary of reported imaging findings. If a hypovascular renal mass with an unclear margin can be found in those with GPA, unnecessary operations may be avoided by actively promoting renal biopsy.

The Differential Diagnosis of Medullary-Based Renal Masses

CONTEXT.—

Renal malignancies can be divided into cortical- and medullary-based tumors, the latter of which classically infiltrate the renal parenchyma by extending between nonneoplastic structures. Although high-grade cortical tumors can rarely exhibit the same growth pattern, the infiltrative morphology should elicit a differential diagnosis to be considered in each case. However, these diagnoses can be challenging to distinguish, especially on small renal biopsy samples.

OBJECTIVE.—

To provide an overview of the clinical, gross, and microscopic findings; genetic and molecular alterations; and immunohistochemical evaluation of medullary-based renal tumors and other tumor types with overlapping morphologies and growth patterns.

DATA SOURCES.—

Literature review and personal observations were used to compile the information in this review.

CONCLUSIONS.—

Collecting duct carcinoma is a prototypical medullary-based tumor, and although diagnostic criteria exist, it remains a diagnosis of exclusion, especially with ancillary techniques aiding the recognition of established as well as more recently described neoplasms. Other medullary-based malignancies included in the differential diagnosis include renal medullary carcinoma/renal cell carcinoma unclassified with medullary phenotype, fumarate hydratase-deficient renal cell carcinoma, and upper tract urothelial carcinoma. Moreover, other rare entities should be excluded, including metastatic carcinoma, lymphoma, and melanoma. In addition to potential prognostic differences, accurate diagnoses can have important surgical and clinical management implications.

Primary renal lymphoma: a comprehensive review of the pathophysiology, clinical presentation, imaging features, management and prognosis

Primary renal lymphoma (PRL) is defined as a non-Hodgkin's lymphoma restricted to kidneys with the absence of extensive nodal disease. It is an exceedingly rare clinicopathological entity, accounting for 0.7% of extranodal lymphomas. Published medical literature regarding the natural history and clinical outcomes of PRL remains limited. We describe a case of a young patient who presented with left shoulder pain, continuous fever, and unexplained weight loss as atypical initial manifestations of bilateral PRL, confirmed with the standard set of investigations. Furthermore, this article reviews the literature and discusses various aspects of PRL, including pathophysiology, presentation patterns, imaging and pathological characteristics, management, and prognosis. This paper serves to provide an update and aims to enhance the understanding of PRL. Timely diagnosis and treatment are imperative to achieve improved outcomes. Clinicians should maintain a high index of suspicion in order to prevent morbidity and mortality associated with this serious disease.

An Unusual Presentation of T-Cell Lymphoblastic Lymphoma with Isolated Renal Involvement

The clinical presentation of Non-Hodgkin lymphoma (NHL) is frequently associated with the involvement of the abdomen and mediastinal lymphadenopathies, but rarely the kidney, ovaries, and testicles. Here, we report a rare case of T-cell lymphoblastic lymphoma (T-LBL) presenting with bilateral nephromegaly without acute renal failure (ARF) as the first manifestation. A 30-month-old boy was admitted to the department of pediatric nephrology exhibiting abdominal distension. Physical examination revealed bilateral renal palpation up to the inguinal region. Elevated lactate dehydrogenase (LDH) levels were detected in his blood. Bilateral diffuse enlarged kidneys with increased hypoechogenicity were found on abdominal ultrasonography. In the next step, contrast-enhanced computed tomography showed diffusely enlarged kidneys, which were compressing the intestinal bowels and midline structures. Renal biopsy demonstrated precursor T-LBL. We wish to report our patient with renal T-LBL presenting with diffuse renal enlargement, which has rarely been reported in the literature.

Contrast-enhanced computed tomography findings of canine primary renal tumors including renal cell carcinoma, lymphoma, and hemangiosarcoma

In veterinary medicine, abdominal ultrasonography is used to rank the differential diagnosis of renal lesions. However, a conventional sonographic examination may show nonspecific findings. The purpose of this study was to assess the computed tomography (CT) findings of canine renal tumors, including renal cell carcinoma (RCC), lymphoma, and hemangiosarcoma (HSA). In this retrospective study, the following CT parameters were recorded for each dog: 1) extent of renal involvement of tumors, 2) enhancement pattern, 3) number of renal tumors, 4) renal tumor vessel enhancement in the corticomedullary phase, 5) presence of lymphadenopathy and lung metastasis, and 6) attenuation values of the renal tumors on the pre- and post-contrast corticomedullary, nephrographic, and excretory phase images. Fifteen dogs met the inclusion criteria, of which nine had RCCs, four had lymphomas, and two had HSAs. RCCs tended to show heterogeneous enhancement and unilateral renal involvement, and vessel enhancement was detected in the corticomedullary phase in dogs with RCC. Conversely, renal lymphomas showed homogeneous enhancement, bilateral renal involvement, and multiple masses; in these dogs, no vessel enhancement was detected in the corticomedullary phase, and the incidence of lymphadenopathy was low. However, in dogs with lymphadenopathy, the renal lymphoma was associated with regionally severe lymphadenopathy. Finally, renal HSAs tended to show heterogeneous enhancement with a non-enhanced area and unilateral renal involvement; in these dogs, vessel enhancement was detected in the nephrographic phase, with the enhancement expanding around the vessel. These findings had no significant differences. Further studies with a larger sample size are required to examine the association between CT and histopathological findings.

Differential diagnostic ability of 18F-FDG PET/CT radiomics features between renal cell carcinoma and renal lymphoma

BACKGROUND

The aim of this study is to determine the differential diagnostic value of texture parameters of PET/CT on renal cell carcinoma and renal lymphoma.

METHODS

Twenty renal lymphoma and 18 renal cell carcinoma (RCC) patients were analyzed in this study. The pathological information and basic characteristics were extracted from the electronic medical record system of our hospital. We used LIFEx package to extract data from the radiomics images. Receiver operating characteristic analysis and binary logistic regression analysis was applied in determining the diagnostic accuracy of texture parameters as well as the synthetic parameter, of which the sensitivity and specificity was improved.

RESULTS

There were 14 (two in Histogram, two in Grey Level Co-occurrence Matrix, five in Grey-Level Run Length Matrix, five in Grey-Level Zone Length Matrix) out of the texture parameters showing an area under the curve (AUC) >0.7 and P<0.05. Synthesized parameters of each section showed even higher differentiation ability, with AUC varying from 0.725 to 1.000.

CONCLUSIONS

Texture analysis of ¹⁸F-FDG PET/CT could effectively differentiate between RCCs and renal lymphomas.

Renal Dysfunction in Patients With Direct Infiltration by B-Cell Lymphoma

Background

B-cell lymphoproliferative disorders with renal involvement are relatively frequent, but remain poorly described. A kidney biopsy is usually required to detect the renal lesions that are often missed using other diagnostic tools.

Methods

We retrospectively identified 34 patients with renal lymphoma diagnosed by percutaneous kidney biopsy (PKB) at Rennes University Hospital and its affiliated hospital centers between January 1, 2004, and May 1, 2016. Clinical, biological, radiological, and histological characteristics were collected at biopsy time.

Results

The included patients had Waldenström macroglobulinemia (n = 12; 35.3%), chronic lymphocytic leukemia/lymphocytic lymphoma (n = 10; 29.5%), high-grade B-cell lymphoma (n = 6; 17.6%), and low-grade B-cell lymphoma (n = 6; 17.6%). The median follow-up was 29 months. Renal involvement led to renal function impairment in 29 patients (85.3%), among whom 20 had acute kidney injury (70%), and to nephrotic syndrome in 4 patients (11.8%). Only 13 patients (38.2%) presented morphological kidney anomalies among whom 5 showed bilateral infiltration. Histologically, interstitial infiltrate (97.1%) was the most common kidney lesion, and 9 patients (26.5%) had specific lymphomatous intraglomerular lesions. After hematological treatment (n = 29), a renal response was observed only in 8 patients (27.6%).

Conclusion

Renal involvement in the context of B-cell lymphoproliferative disorders is not uncommon. PKB is the best method to confirm this diagnosis. It should be performed early to rapidly initiate the hematological treatment to preserve kidney function.

Imaging of Unusual Renal Tumors

PURPOSE OF REVIEW

Renal masses are a wide entity and a common finding in clinical practice. Detection of these masses has increased in the last years, yet mortality rates have slightly decreased.

RECENT FINDINGS

According to the World Health Organization classification, there are 8 types, 51 subtypes, and a lot more subsequent subclassifications of renal tumors. Histopathological analysis should always be assessed for final diagnosis of theses tumors. However, imaging can be an important diagnostic guidance. The most common diagnoses of renal tumor are clear cell carcinoma, papillary renal cell carcinoma, angiomyolipoma, and transitional cell carcinoma. Nonetheless, a considerable variety of particular tumors can arise from the kidney, challenging the expertise of radiologists and urologists on this subject. The awareness of these unusual entities is vital for professionals working at a complex medical facility with greater volume of patients. We hereby present uncommon renal tumors and its pathological and radiological features.

Imaging of Solid Renal Masses

The increase in serendipitous detection of solid renal masses on imaging has not resulted in a reduction in mortality from renal cell carcinoma. Consequently, efforts for improved lesion characterization have been pursued and incorporated into management algorithms for distinguishing clinically significant tumors from those with favorable histology or benign conditions. Although diagnostic imaging strategies have evolved for optimized lesion detection, distinction between benign tumors and both indolent and aggressive malignant neoplasms remain an important diagnostic challenge. Recent advances in cross-sectional imaging have expanded the role of these tests in the noninvasive characterization of solid renal tumors.

Renal Mucinous Tubular and Spindle Cell Carcinoma Shows a High Uptake on 18F-FDG PET/CT

We herein report a rare case of mucinous tubular and spindle cell carcinoma (MTSCC) in an 80-year-old woman. A well circumscribed tumor located on the right kidney was discovered incidentally as a result of screening non-contrast CT. Fluorodeoxyglucose positron emission tomography (FDG PET)/CT showed the increased tracer accumulation in the tumor. The histological diagnosis was MTSCC, which is a rare and only recently established subtype of the malignant renal cell carcinoma (RCC). The present case suggests the clinical benefit of a high uptake of FDG combined with enhanced contrast CT in the differentiation of MTSCCs and other RCCs.

CT imaging spectrum of infiltrative renal diseases

Most renal lesions replace the renal parenchyma as a focal space-occupying mass with borders distinguishing the mass from normal parenchyma. However, some renal lesions exhibit interstitial infiltration-a process that permeates the renal parenchyma by using the normal renal architecture for growth. These infiltrative lesions frequently show nonspecific patterns that lead to little or no contour deformity and have ill-defined borders on CT, making detection and diagnosis challenging. The purpose of this pictorial essay is to describe the CT imaging findings of various conditions that may manifest as infiltrative renal lesions.

Imaging of Extranodal Genitourinary Lymphoma

The genitourinary (GU) system is commonly affected by disseminated lymphoma. Rarely, lymphoma can originate from and remain localized to one of the GU organs and thus presents as primary extranodal disease. Up to 40% of lymphomas present as extranodal disease, with only 3% having the GU system as the primary site of involvement. This article describes and correlates the radiologic and pathologic features of extranodal lymphomatous disease affecting the GU system with specific focus on the kidneys, adrenal glands, testicles, and ovaries. Lymphoma of the uterine body and cervix, external female genitalia, urinary bladder, and prostate gland is briefly discussed.

Primary cardiac lymphoma with unusual presentation: A report of two cases

Primary cardiac tumors are rare, with an incidence of 0.056% according to autopsy reports. The most common type is myxoma, while other types, including sarcoma, lipoma, papillary fibroelastoma, rhabdomyoma, fibroma, hemangioma, teratoma, lymphoma and mesothelioma also occur. Primary cardiac tumors usually cause embolization, pericardial effusion and arrhythmia, leading to heart failure. Only 10% of primary cardiac tumors are malignant, approximately 95% of which are sarcomas, while the remaining 5% are cardiac lymphomas and mesotheliomas. The present study reported a case of primary cardiac lymphoma (PCL) with bilateral renal involvement and a case of PCL with bilateral adrenal gland involvement. The prognosis of PCL is poor due to the low rate of early detection and treatment. The definitive diagnosis is dependent on pathology, and timely treatment with chemotherapy can be effective. The two cases developed life-threatening arrhythmia and responded to the initial chemotherapy. In the first case, complete remission was achieved after finalization of therapy. However, the second case refused further chemotherapy and succumbed to his condition after two months.

Radiological diagnosis of perinephric pathology: pictorial essay 2015

The perinephric space, shaped as an inverted cone, sits between the anterior and posterior renal fasciae. It can play host to a variety of clinical conditions encountered daily in the reporting schedule for a radiologist. Lesions may be classified and diagnosed based on their imaging characteristics, location and distribution. A broad range of differential diagnoses can be attributed to pathology sitting within this space, often without clinical signs or symptoms. An understanding of commonly encountered conditions affecting the perinephric space, along with characteristic imaging findings, can illustrate and often narrow the likely diagnosis. The aim of this essay is to describe commonly encountered neoplastic and non-neoplastic entities involving the perinephric space and to describe their key imaging characteristics.

TEACHING POINT

• Despite often a bulky disease, perinephric lymphoma does not produce obstruction or stenosis. • In primarily fatty masses, defects within the renal capsule likely represent angiomyolipoma. • Consider paraganglioma if biopsy is planned; biopsy may lead to catecholamine crisis.

Bilateral perirenal space fibromatosis with renal infiltration: case report and review of literature

Fibromatosis and/or desmoid tumors which constitute less than 1% of all neoplasms and 3.0% of all soft-tissue tumors are pathologically benign proliferations of the fibroblasts but are locally aggressive with infiltrative type of growth and tendency toward recurrence. Bilateral symmetrical perirenal involvement has been described in many conditions which can be renal, subcapsular, or perirenal in origin. However, bilateral perirenal fibromatosis as an isolated presentation was very uncommon. We report an exceptionally rare case of bilateral perirenal fibromatosis with renal infiltration.

Diffuse Large B-Cell Lymphoma Presenting with Bilateral Renal Masses and Hematuria: A Case Report

Renal involvement is most often seen in conjunction with multisystemic, disseminated lymphoma either by direct extension from a retroperitoneal mass or via hematogenous spread. Primary lymphoma of the kidney is not a common entity and it is a controversial issue on account of the absence of lymphatic tissues in the normal kidney. In this case report, we describe a 19-year-old male with hematuria, acute kidney injury, and bilateral renal masses due to massive lymphomatous infiltration of the kidneys, which was diagnosed as diffuse large B-cell non-Hodgkin lymphoma by Tru-Cut biopsy.

Imaging features of haematological malignancies of kidneys

Haematological malignancies are relatively uncommon neoplasms of kidneys. Nevertheless, the incidence of these neoplasms is increasing, partly due to more widespread use of computed tomography and magnetic resonance imaging. This article discusses the clinical and imaging features of renal lymphoma, leukaemia, extra-osseous multiple myeloma, and post-transplant lymphoproliferative disorder. Although there is overlap of imaging features with other more common malignancies, such as transitional and renal cell cancers, the combination of imaging findings and the appropriate clinical picture should allow the radiologist to raise a provisional diagnosis of a haematological neoplasm. This has management implications including the preference for image-guided core biopsies and a shift towards medical rather than surgical therapy.

Primary renal lymphoma-a case report

Primary renal lymphoma is a rare entity representing less than 1% of lesions in the kidney. We present the case of a 42-year-old male who was evaluated for pain and a mass in the abdomen. The computed tomogram of the abdomen showed a large lobulated homogeneously enhancing mass lesion of about 14×12×18 cm, involving the whole of the left kidney and encasing the left renal vessels and ureter. The patient underwent a biopsy, and the histopathology was diffuse large B cell lymphoma, positive for LCA, CD20, PAX 5, Bcl 2 and negative for SIgM, CD33, CD34, CD5, Tdt, with MIB 1 labelling index of 40%. He received chemotherapy with rituximab, cyclophosphamide, doxorubicin, vincristine and prednisolone (R CHOP) for eight cycles followed by radiation to the residual mass and achieved complete remission. Currently, he is alive and in remission at 28 months.

Ultrasonographic characteristics of canine renal lymphoma

There is little published information on the ultrasonographic appearance of canine renal lymphoma. The purpose of this retrospective study was to provide additional information regarding the ultrasonographic characteristics of canine renal lymphoma, suggest ultrasonographic description criteria, and evaluate the role of fine-needle aspirate cytology in the diagnosis of this disease. The ultrasonographic features of confirmed renal lymphoma were reviewed in ten dogs. Pyelectasia was found in all dogs. Other ultrasonographic findings were loss of corticomedullary distinction (9/10 dogs), renomegaly (8/10 dogs), renal deformity (6/10 dogs), hypoechoic lesion(s) (6/10 dogs), and hyperechoic lesion(s) (2/10 dogs). Hypoechoic lesions were described as masses, nodules, and indistinct areas. In 30% of the cases (3/10 dogs) ultrasound revealed only minor abnormalities, including grade 1 pyelectasia, mild renomegaly, and focal loss of corticomedullary definition. Bilateral lesions were seen in nine dogs (90%). Renal fine-needle aspirates were performed in 9/10 dogs, yielding a diagnosis in seven on first attempt (78%). Two dogs had been given a provisional cytological diagnosis of round cell neoplasia; in one dog lymphoma was confirmed by second aspirate and by tissue core biopsy in the other. In 1/10 dogs, lymphoma was found at necropsy. Findings indicated that ultrasonographic signs of canine renal lymphoma may be subtle, canine renal lymphoma should be included in the differential diagnosis when the above ultrasonographic features are observed, and fine-needle aspirate cytology is a useful method for diagnosing this disease.

Multiple hypovascular tumors in kidney: a rare case report and differential diagnosis

The most common malignant renal tumor is renal cell carcinoma and surgery is the standard treatment. The proportion of lymphoma with renal involvement is 2~15% and lymphoma could be cured by chemotherapy without nephrectomy. Sonography, computed tomography (CT), and magnetic resonance imaging (MRI) can detect and characterize a renal mass. We present a case of right renal hypovascular tumors and differential diagnosis of hypovascular tumors by image study. CT scan showed hypovascular tumors and MRI image revealed multifocal hypovascular solid tumors with significantly increased apparent diffusion coefficient (ADC) of diffusion weighted imaging (DWI). Based on image finding, renal lymphoma was highly suspected. Renal lymphoma was confirmed by renal biopsy and this patient received chemotherapy without surgery. The noninvasive CT scan and MRI image can help clinicians to diagnose the characteristics of renal mass and to avoid unnecessary nephrectomy.

Contrast-enhanced ultrasound findings in a case of renal extramedullary hematopoiesis

We present the case of an 80-year-old man with two renal solid masses found at sonography, which were imaged by contrast-enhanced ultrasound, CT, and MRI and confirmed histologically. Contrast-enhanced ultrasound findings suggested a benign mass and a CT-guided biopsy yielded a diagnosis of extramedullary hematopoiesis.

Acute complicated pyelonephritis: contrast-enhanced ultrasound

Imaging is required if complication is suspected in acute pyelonephritis to assess the nature and extent of the lesions, and to detect underlying causes. The current imaging modality of choice in clinical practice is computed tomography. Because of associated radiation and potential nephrotoxicity, CEUS is an alternative that has been proven to be equally accurate in the detection of acute pyelonephritis renal lesions. The aims of this study of 48 patients are to describe in detail the CEUS findings in acute pyelonephritis, and to determine if abscess and focal pyelonephritis may be distinguished. Very characteristic morphologic and temporal patterns of enhancement are described. These allow differentiation of focal pyelonephritis from renal abscess, and detection of tiny suppurative foci within focal pyelonephritis. The detection of abscesses is important because follow-up in 25 patients revealed a longer clinical course. Typical pyelonephritis CEUS features permit distinction from other renal lesions. As a whole, CEUS is an excellent tool in the work-up of complicated acute pyelonephritis, so it may be considered as the imaging technique of choice in the evaluation and follow-up of these patients who frequently are very young, so as to minimise radiation exposure.

Acute kidney injury and bilateral symmetrical enlargement of the kidneys as first presentation of B-cell lymphoblastic lymphoma

Lymphoblastic lymphoma is an uncommon subtype of lymphoid neoplasm in adults. Acute kidney injury at initial presentation due to lymphoblastic lymphoma infiltration of the kidneys has rarely been described. We report a 19-year-old woman who presented with acute kidney injury due to massive lymphomatous infiltration of the kidneys. The diagnosis of B-cell lymphoblastic lymphoma was established by immunohistochemical study of the biopsied kidney. The patient had an excellent response to the VDCLP protocol (vincristine, daunomycin, cyclophosphamide, asparaginase, and dexamethasone) with sustained remission. We recommend that lymphomatous infiltration be considered in patients presenting with unexplained acute kidney injury and enlarged kidneys.

Common and less-common renal masses and masslike conditions

As an increasing number of imaging examinations are performed, a greater number of incidental renal lesions are detected. Apart from the usual cysts and solid renal cell carcinomas, a variety of unusual benign and malignant renal lesions exist. Imaging is invaluable in characterizing these lesions and is confirmatory in some benign lesions. Renal cell carcinoma remains the diagnosis of exclusion; however, assessment of the imaging pattern in the appropriate clinical context can improve diagnostic accuracy. The objective of this article is to familiarize the radiologist with the imaging appearance of unusual non-neoplastic and neoplastic lesions and correlate with histopathologic studies when available.

Prevalence and patterns of renal involvement in imaging of malignant lymphoproliferative diseases

BACKGROUND

Renal involvement in patients with lymphoproliferative disease is an uncommon radiological finding.

PURPOSE

To determine its prevalence and radiological appearances in a patient population.

MATERIAL AND METHODS

All forms of lymphoproliferative disease (ICD: C81-C96) were considered. From January 2005 to January 2010, 668 consecutive patients with lymphoproliferative disease were identified with the help of the radiological database and patient records. Inclusion criteria were complete staging including appropriate CT scan and/or MRI. All stored images (initial staging and follow-up examinations) were reviewed.

RESULTS

Review of all stored images revealed renal infiltration in patients with non-Hodgkin lymphoma (11 of 364 = 3.0%; median age = 65 years, m:f = 6:5) but also multiple myeloma (2 of 162 = 1.2%; median age = 72 years; m:f = 1:1) and leukemia (5 of 101 = 4.9%; median age = 12 years; m:f = 2:3). There were no cases of renal infiltration in 41 patients with Hodgkin's disease. In total there were six patients with solitary lesions, five patients with diffuse renal enlargement, four patients with perirenal lesions, and two patients with direct invasion of the kidney.

CONCLUSION

In leukemia the most common imaging pattern is diffuse enlargement. In the other subtypes of lymphoproliferative disease no specific correlation between typical CT patterns and subtype of lymphoproliferative disease can be found. The prevalence of renal involvement is in line with earlier studies. Contrary to earlier reports, multiple lesions were not found to be a common pattern.

Renal MALT lymphoma associated with Waldenström macroglobulinemia

Mucosa associated lymphoid tissue lymphoma (MALT lymphoma) is mostly seen in the gastrointestinal tract; origin from the kidney is extremely rare. Waldenström macroglobulinemia (WM) is a clinicopathologic syndrome denoted by the presence of monoclonal gammopathy in the serum, typically caused by lymphoproliferative disorder. Literature review did not find any report of renal MALT lymphoma accompanied by WM. Herein, for the first time, we report a 72 year-old female patient with a history of chronic kidney disease, presenting with solitary renal mass; MALT lymphoma was confirmed by pathological examination. A serology study identified the presence of WM. No manifestation of hyperviscosity syndrome was noted. Bone marrow biopsy disclosed the concurrent systemic involvement. Her treatment response was uneventful and the renal mass responded with regressive change in size after chemotherapy. The renal function remained stable during follow-up. MALT lymphoma should be considered as an underlying pathology of isolated renal mass. Furthermore, patients with MALT lymphoma should be screened for Waldenström macroglobulinemia and hyperviscosity syndrome.

Papillary renal cell carcinoma with extensive paraaortic nodal metastasis mimicking malignant lymphoma

A 52-year-old woman with abdominal distension underwent computed tomography (CT) that demonstrated extensive paraaortic lymphadenopathy and a right renal mass. Compared to the renal cortex, the lesions exhibited low signal intensity on T(1)- and T(2)-weighted images and high intensity on diffusion-weighted magnetic resonance (MR) images. We suspected malignant lymphoma and performed excisional biopsy, which revealed metastatic papillary renal cell carcinoma. Retrospectively, significantly reduced signal on in-phase chemical shift MR images compared to out-of-phase images suggested the presence of intratumoral hemosiderin, a characteristic finding of this entity.

Precursor T-lymphoblastic lymphoma presenting as primary renal lymphoma with acute renal failure

We report a case of acute renal failure (ARF) and bilateral nephromegaly in a patient with a history of Crohn’s disease and treatment with azathioprine. Kidney biopsy revealed diffuse renal infiltration by precursor T-cell lymphoblastic lymphoma (T-LBL). At the time of diagnosis, no extrarenal manifestations of the lymphoma were detectable and therefore the lymphoma was categorized as primary renal lymphoma (PRL). Thus far, precursor T-LBL presenting as PRL has not been described before. We emphasize that in patients with ARF and bilateral renal enlargement, renal lymphoma is an important differential diagnostic consideration.

Assessment and characterisation of common renal masses with CT and MRI

Objective

Owing to the widespread use of abdominal imaging studies the detection rate of solid renal masses has increased, and an accurate characterisation of imaging features of renal masses has become more essential for case management.

Method and results

MR imaging (MRI) and computed tomography (CT) are frequently used modalities for detection and differentiation of renal masses. This article gives a review of imaging characteristics of benign and malignant renal masses, discussing their appearance in CT and MR imaging. Advanced MR techniques like diffusion-weighted imaging and apparent diffusion coefficient (ADC) mapping, which have shown promising results in the differentiation between benign and malignant renal lesions, will be introduced.

Conclusion

MRI and CT are useful in the characterisation and estimation of the prognosis for renal masses.

Diffuse FDG renal uptake in lymphoma

In patients presenting with acute renal failure and known/suspected lymphoma, the diagnosis of diffuse renal involvement is important, as there is potential for rapid resolution with chemotherapy. Although FDG is excreted through the kidneys and focal renal disease may be difficult to identify, diffuse renal FDG is more easily recognized and is always abnormal. We report a patient presenting with acute renal failure and suspected lymphoma. F-18 FDG PET/CT study demonstrated diffuse increased FDG uptake in bilaterally enlarged kidneys. Following 1 cycle of chemotherapy, the renal function normalized. An interim F-18 FDG PET/CT demonstrated normal size and FDG uptake within both kidneys.

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.

MR imaging for acute lower abdominal and pelvic pain

Acute lower abdominal and pelvic pain is a frequent complaint of patients in the emergency room. Usually, the condition of these patients is assessed with computed tomography (CT) and ultrasonography (US). However, the need to reduce radiation doses of as much as 20 mSv at CT, especially in younger patients and possibly pregnant patients, and the operator dependence of US have led to an increased use of magnetic resonance (MR) imaging to assess those patients. MR imaging shows high accuracy in these patients and can be used to establish an accurate diagnosis quickly and reliably. A short imaging protocol of about 10 minutes, without the use of an intravenous contrast agent in most cases, allows investigation of these patients. The basic imaging protocol that localizes the diseased anatomic region needs to be complemented by focused anatomic imaging of the diseased area. Although MR imaging might not be the modality of choice for all patients, it may be beneficial for a subset of patients for whom CT is not warranted (pregnant patients or young patients) and US findings are inconclusive. In patients with acute abdominal and pelvic pain, the range of diseases and disorders that can be diagnosed with MR imaging is extremely broad. Therefore, MR imaging should be considered as an excellent imaging modality for the evaluation of these patients.

Magnetic resonance imaging of renal masses

The increasing frequency of incidentally detected renal masses supports the need for accurate imaging characterization to avoid unnecessary surgery/interventional procedures. Furthermore, the need for accurate presurgical diagnosis of specific histologic subtypes of renal malignancies is increasingly important as advances in understanding of tumor biology direct targeted courses of therapy. Magnetic resonance imaging is uniquely suited for the evaluation of renal masses because of its ability to provide excellent soft-tissue contrast and demonstration of enhancement, as well as its multiplanar capabilities. Although the spectrum of masses that may occur in the kidneys is broad, specific imaging features may assist in their accurate diagnosis. Examples of the imaging appearance of common and uncommon renal masses are provided along with a protocol for comprehensive magnetic resonance examination of the kidneys.

Biopsy of renal masses: when and why

Percutaneous image-guided biopsy of renal masses is a safe and accurate procedure. Although once reserved for the diagnosis of unresectable renal cell carcinoma, metastases, lymphoma, and infection, today percutaneous image-guided biopsy has an expanded role. There is increasing awareness that a substantial proportion of small, solid renal masses are benign neoplasms. Although imaging can be used to diagnose most of them, some are incorrectly believed to represent renal cell carcinoma and unnecessary surgery may be performed. Based largely on advances in cytological techniques, percutaneous biopsy can be now be used to diagnose benign neoplasms and thus prevent them from being treated unnecessarily. Concurrent advances in percutaneous ablation have also promoted its use. As a result, there are 8 established indications for percutaneous biopsy, and reason to believe that the number of indications will expand further in the future.

MR imaging of renal masses: correlation with findings at surgery and pathologic analysis

Magnetic resonance (MR) imaging is useful in the characterization of renal masses. The MR imaging manifestations and pathologic diagnoses of 82 renal masses were reviewed and correlated. The MR imaging appearance of clear cell type renal cell carcinoma varies depending on the presence of cystic components, hemorrhage, and necrosis. Papillary renal cell carcinomas appear as well-encapsulated masses with homogeneous low signal intensity on T2-weighted images and homogeneous low-level enhancement after the intravenous administration of contrast material, or as cystic hemorrhagic masses with peripheral enhancing papillary projections. Transitional cell carcinoma may be seen as an irregular, enhancing filling defect in the pelvicaliceal system or ureter. Lymphomatous masses are usually hypointense relative to the renal cortex on T2-weighted images and enhance minimally on delayed gadolinium-enhanced images. Bulk fat is a distinguishing feature of angiomyolipoma. Oncocytoma has a variable and nonspecific appearance at MR imaging. MR imaging findings may allow the characterization of various renal masses and can provide valuable information for their clinical management.

Imaging of abdominal lymphoma

This article discusses the radiologic appearances of solid organ involvement with Hodgkin and non-Hodgkin lymphoma in the abdominopelvic region. The most common radiologic patterns of involvement are illustrated. The imaging characteristics of lymphomatous involvement of abdominal organs overlap with several other disorders and the specific features pertaining to lymphoma are highlighted. In patients who have known lymphomas, other important management considerations, such as staging, response to therapy, malignant transformation, and identification of recurrent disease, are also discussed. The emerging role of fluorodeoxyglucose positron emission tomography is briefly outlined.