Imaging of angiomyolipomas

Sirolimus can promote the disappearance of renal angiomyolipoma associated with tuberous sclerosis complex: a prospective cohort study

BACKGROUND

Renal angiomyolipoma (RAML) is the most common kidney lesion in patients with tuberous sclerosis complex (TSC), affecting about 80% of patients. It is a benign tumor that grows over time, usually bilaterally, and can easily lead to kidney complications such as acute hemorrhage. Herein, we investigated the efficacy and safety of sirolimus in children with TSC-associated RAML and explored the factors affecting tumor disappearance under sirolimus treatment through subgroup analysis.

METHODS

A prospective cohort study was conducted. Sirolimus was initiated at 1 mg/(m2 × day), and dose adjustments were made by a 2-week titration period to attain a trough blood concentration of 5-10 ng/mL. The disappearance of RAML in children after sirolimus treatment was observed, and Cox regression was used to screen the factors affecting tumor disappearance.

RESULTS

One hundred and twenty-six patients who met the criteria were analyzed. After 3 months, 6 months, 12 months, and 24 months of follow-up, tumors disappeared in 18 (14.3%), 30 (23.8%), 39 (31.0%), and 42 (33.3%) children, respectively. Tumors disappeared in 50 (39.7%) children by the last visit of each individual, and 30 (60%) of them occurred within 6 months. The multivariate Cox regression analysis showed that patients with a smaller maximum tumor diameter at baseline had a higher tumor disappearance rate. Thirty-six (29%) patients had stomatitis during the entire treatment period, and no serious adverse reactions were observed.

CONCLUSIONS

Sirolimus could promote the disappearance of TSC-related RAML. The disappearance rate was correlated with the maximum diameter at baseline, and the smaller the tumor was, the higher the disappearance rate. It is well tolerated in the treatment of RAML associated with TSC.

Autopsy findings of fatal retroperitoneal hemorrhage after traumatic rupture of bilateral renal angiomyolipoma

The present work reports the autopsy findings of a unique case characterized by fatal retroperitoneal hemorrhage following the traumatic rupture of bilateral renal angiomyolipomas. Renal angiomyolipomas are generally benign tumors with an unpredictable clinical course, ranging from asymptomatic to sudden rupture and hemorrhagic shock. They may be associated with genetic disorders such as tuberous sclerosis complex. The case under investigation is unprecedented in the medical literature due to its bilateral nature and fatal outcome. Autopsy analysis revealed an extensive retroperitoneal hemorrhage originating from bilateral ruptured tumors. Microscopic examination found features consistent with bilateral renal angiomyolipoma. Circumstantial information identified a traffic accident before the death, considering it as the cause of the tumors' traumatic rupture. In this case, due to the severity of the situation, immediate medical measures-such as fluid resuscitation, coagulopathy correction, and surgical treatment, which are usually lifesaving-could not be performed. This led to the patient being declared dead at the scene of the crash.

Factors predicting the active treatment of renal angiomyolipoma: 30 years of experience in two tertiary referral centers

Introduction and objective

This study aimed to identify clinical features representing predictive factors of active treatment (AT) compared to active surveillance (AS) for renal angiomyolipoma (AML).

Patients and methods

From 1990 to 2020, patients referred to two institutions for a renal mass and diagnosed with an AML based on typical features on CT were included in the analysis. The study population was divided into two groups based on the treatment received: active surveillance (AS) or active treatment (AT). Age, gender, tuberous sclerosis syndrome, tumor size, contralateral kidney disease, renal function, year of diagnosis, and symptoms at presentation were assessed as potential predictive factors of active treatment using a logistic regression model in univariate and multivariate analyses.

Results

In total, 253 patients (mean age 52.3 ± 15.7 years; 70% women; 70.9% incidentally diagnosed) were included in the analysis. One hundred and nine (43%) received AS, whereas 144 (57%) were actively treated. For univariate analysis, age, tuberous sclerosis complex syndrome, tumor size, symptoms at presentation, and contralateral kidney disease were found to be predictors of AT. Only tumor size (p < 0.001) and the year of diagnosis (p < 0.001) remained significant for multivariable analyses. The likelihood of being managed with AS evolved over the study period and was 50% and 75% when diagnosed before and after 2010, respectively. With respect to size, 4-cm and 6-cm tumors had a probability of 50% and 75% of being treated with AS, respectively.

Conclusion

The present analysis from a high-volume institution provides evidence that the management of renal masses with typical radiological features of AML has markedly changed over the last three decades with a trend toward AS over AT. Tumor size and the year of diagnosis were significant factors for the treatment strategies.

Spontaneous rupture of renal angiomyolipoma and its management: A case report

a) Introduction and Importance

Angiomyolipomas of kidney are benign lesions that are generally an incidental finding on imaging. Rupture of angiomyolipoma is rare and fatal complication that requires early intervention.

b) Case Presentation

A 38 year old male patient presented with symptoms of right flank pain for 2 days. On clinical examination patient looked anxious, pale with right flank tenderness, guarding and signs of shock.

c) Clinical findings and investigations

CT scan showed renal angiomyolipoma with aneurysm formation and bleed from the lesion. Blood profile revealed low hemoglobin.

d) Interventions and Outcome

Right nephrectomy performed along 6 cycles of cardiopulmonary reususcitaion done with stable post operatively vitals.

e) Conclusion

Early diagnosis of complication of angiomyolipoma requires thorough clinical examination and judicious use of imaging. Immediate embolization or surgery must be performed for better outcome and survival rate.

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Angiomyolipoma is composed of fat, smooth muscle and blood vessels and presents among 0.3% of the population.

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Renal angiomyolipoma are prone to aneurysm formation and bleed, however a nontraumatic spontaneous renal hemorrhage from a sporadic renal angiomyolipoma is a rare condition.

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Mostly angiomyolipoma are asymptomatic and are diagnosed incidentally. CT scan is the diagnostic modality of choice.

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Patients with life-threatening hemorrhage require immediate intervention that includes embolization or surgery for better outcome and survival rate.

Renal hematuric angiomyolipomas embolization: three cases and literature review

We report three cases of hemorrhagic renal angiomyolipoma successfully treated using embolization. Endovascular management of this complication is highlighted.

Different Treatments of Symptomatic Angiomyolipomas of the Kidney: Two Case Reports

Development of more sensitive imaging techniques has caused an increase in the number of diagnosed small renal tumors. Approximately 2-3% of these lesions are proved to be angiomyolipomas (AML), a rare benign tumor of the kidney sometimes causing pain and hematuria. The most required approach is observation, but in the case of recurrent symptoms or larger tumors, which may cause bleeding, a more active treatment is required. We present two cases of symptomatic AML tumors of different sizes in the kidney: one treated with transarterial embolization (TAE), and the other with percutaneous cryoablation (CRA). The lesions were diagnosed on the basis of contrast-enhanced computed tomography (CT) scan and magnetic resonance imaging (MRI). Both treatments proved to be effective and safe for treating renal AMLs. A follow-up carried out, based on contrast-enhanced CT scan, confirmed complete treatment of AML and decreased lesion size. There are myriad minimally invasive approaches for the treatment of renal AMLs, and the preservation of renal function remains a priority. The most popular treatment option is the selective renal artery embolization. Owing to its limited invasiveness, CRA could be an attractive option for the preventive treatment of AML.

Updated International Tuberous Sclerosis Complex Diagnostic Criteria and Surveillance and Management Recommendations

BACKGROUND

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disease affecting multiple body systems with wide variability in presentation. In 2013, Pediatric Neurology published articles outlining updated diagnostic criteria and recommendations for surveillance and management of disease manifestations. Advances in knowledge and approvals of new therapies necessitated a revision of those criteria and recommendations.

METHODS

Chairs and working group cochairs from the 2012 International TSC Consensus Group were invited to meet face-to-face over two days at the 2018 World TSC Conference on July 25 and 26 in Dallas, TX, USA. Before the meeting, working group cochairs worked with group members via e-mail and telephone to (1) review TSC literature since the 2013 publication, (2) confirm or amend prior recommendations, and (3) provide new recommendations as required.

RESULTS

Only two changes were made to clinical diagnostic criteria reported in 2013: "multiple cortical tubers and/or radial migration lines" replaced the more general term "cortical dysplasias," and sclerotic bone lesions were reinstated as a minor criterion. Genetic diagnostic criteria were reaffirmed, including highlighting recent findings that some individuals with TSC are genetically mosaic for variants in TSC1 or TSC2. Changes to surveillance and management criteria largely reflected increased emphasis on early screening for electroencephalographic abnormalities, enhanced surveillance and management of TSC-associated neuropsychiatric disorders, and new medication approvals.

CONCLUSIONS

Updated TSC diagnostic criteria and surveillance and management recommendations presented here should provide an improved framework for optimal care of those living with TSC and their families.

Giant bilateral angiomyolipoma of the kidney

Angiomyolipoma is a benign solid renal neoplasm. A giant angiomyolipoma is more than 10cm by size, but it can grow to huge proportions. Our case appears to be the third largest angiomyolipoma and the largest among bilateral giant renal angiomyolipoma in the indexed literature. A 26-year-old man presented with large right abdominal swelling for the past three years, which was occupying his right flank and iliac region, extending beyond the midline. Computed tomography of the abdomen revealed a large well-defined mass in the right side of the abdomen, crossing the midline and measuring 35 × 20 × 12cm. The left kidney showed a similar fatty lesion of 14 × 6cm. The findings were consistent with angiomyolipoma. Further evaluation for tuberous sclerosis by magnetic resonance imaging the brain demonstrated multiple subependymal nodules. Giant renal angiomyolipoma is an uncommon tumour with bilateral giant angiomyolipoma being a rare entity. Preoperative embolisation helps in reducing size of the tumour. In case of giant and bilateral angiomyolipoma, evaluation for tuberous sclerosis should always be done.

Renal angiomyolipoma with tuberous sclerosis complex: How it differs from sporadic angiomyolipoma in both management and care

Renal angiomyolipoma (AML) is the most common benign tumor of the kidney. It consists of blood vessels, smooth muscle and fat components in varying proportions. AML is divided into the sporadic type and tuberous sclerosis complex (TSC)-associated type. TSC-associated AML develops at a younger age and tends to exhibit a much faster growth rate over time than sporadic AML. AMLs are classified as classic AML, fat-poor AML and epithelioid AML. Epithelioid AML, though rare, shows aggressive behavior leading to distant metastasis and mortality. TSC-associated AML is more likely to have an epithelioid component than sporadic AML. Active surveillance is the suggested management for small AML. Clinical intervention is mainly indicated when there is a substantial risk of rupture. Minimally invasive therapies, including partial nephrectomy, transcatheter arterial embolization, and mammalian target of rapamycin (mTOR) inhibitor treatment are employed for patients who require treatment. An updated algorithm for the management of AML is herein described. According to this algorithm, treatment intervention is recommended for TSC-associated AML >3 cm, even in asymptomatic cases. In cases with asymptomatic sporadic AML >4 cm in size or with an intra-tumoral aneurysm of >5 mm, treatment, including transcatheter arterial embolization or partial nephrectomy, is advised. The major complication of AML is intra-tumoral or retroperitoneal hemorrhage due to rupture that may be serious and life threatening. Thus, correct diagnosis, proper observation, and appropriate treatment are very important in the management of renal AML.

Wunderlich Syndrome: An Unusual Cause of Abdominal Pain with Hypovolaemia

Wunderlich syndrome, or spontaneous retroperitoneal haemorrhage, is a rare but potentially fatal condition. I report a case of a middle-aged lady who presented with this rare condition where a bedside point-of-care ultrasound scan expedited the management of the patient. (Hong Kong j.emerg.med. 2013;20:385-388)

Laparoscopic cryoablation of angiomyolipomas in adolescents and young adults: A report of four cases associated with tuberous sclerosis and 1 case of sporadic origin

INTRODUCTION

Renal angiomyolipomas (AMLs) can be of sporadic origin or associated with tuberous sclerosis (TS). TS-associated AMLs often present in childhood, tend to be bilateral and multiple, and often exhibit a faster growth rate with an increased risk of hemorrhage. Renal cryoablation is well described in adults, whereas experiences with adolescents and young adults are limited. We present here for the first time a series of renal AMLs within adolescents and young adults treated with laparoscopic assisted cryoablation (LCA).

OBJECTIVE

The aim was to evaluate whether LCA of AMLs in adolescents and young adults is a safe and feasible treatment modality.

STUDY DESIGN

From October 2009 to September 2013 a total of five patients at our institution were diagnosed with AMLs requiring treatment. Four patients had TS and one had AML of sporadic origin, all five patients underwent LCA. Data were retrospectively collected by a systematic review of patient material and reassessment of renal imaging.

RESULTS

The median age was 16 years (range 13-27 years). Eight AMLs with a median size of 3.9 cm (range 2.1-7.7 cm) were treated in five patients because of tumor size and rapid growth. Follow-up was a median 37 months (range 20-62 months), and all tumors showed a reduction in tumor size, and no regrowth was recognized (see summary table). The procedure was well tolerated, with only few perioperative complications and no postoperative complications.

DISCUSSION

When considering the indication for treating AMLs, the origin (sporadic or TS associated) and size of the tumor are the decisive factors. To preserve renal function and prevent spontaneous hemorrhage caution should be intensified when tumors reach 4 cm, particularly if TS is present. After the diagnosis is established, patients should be monitored with renal imaging at regular intervals to identify rapid-growing tumors. As an alternative to current treatment modalities such as partial nephrectomy and super selective angioembolization, cryoablation is an emerging approach, although experience with pediatric patients is limited. For patients not requiring immediate surgery, pharmacological treatment with mTOR inhibitors is now being evaluated as an alternative treatment option or as neo-adjuvant therapy to ablative techniques.

CONCLUSION

Prophylactic treatment of large or rapid growing AMLs with LCA appears to be a safe and feasible nephron-sparing approach in adolescents and young adults. The low perioperative complication rate and promising effect on outcome might allow treatment of subclinical AMLs in order to minimize the risk of potentially life-threatening complications and preserve renal function.

Diagnosis of Renal Angiomyolipomas: Classic, Fat-Poor, and Epithelioid Types

With the increasing discovery of small renal masses with cross-sectional imaging, there has been the concomitant rise in their treatment. With the intent of early curative surgery for a presumed renal cell carcinoma, many renal masses are being resected at surgery without a confirmed diagnosis. Many of them are benign, and some are angiomyolipomas. The diagnosis of renal angiomyolipoma using imaging is, therefore, is as important as ever. Although most, if not all angiomyolipomas with abundant fat are diagnosed readily, some have too little fat to be detected with imaging. This article reviews the current classification, imaging pitfalls, and diagnosis of angiomyolipoma with an emphasis on the fat-poor types. Proper imaging technique, a thorough search for fat, and the appropriate use of percutanoeus biopsy are all needed to eliminate the unnecessary treatment of these benign neoplasms.

Angiomyolipoma and Malignant PEComa: Discussion of Two Rare Adrenal Tumors

Angiomyolipoma and PEComa are rare tumors descending from perivascular epithelial cells (PECs), with distinctive IHC, morphological, and ultrastructural features. The kidney is the most frequent site of origin, but not the only one; however, adrenal gland angiomyolipomas are extremely rare. We describe two cases being found in the adrenal glands. Given the paucity of literature on the subject, more information on this disease is necessary for diagnosis and treatment. Here, we describe two complete case reports, from presentation to treatment and follow-up, along with imaging and microscopic pathology samples, and provide a comprehensive review as to the history and current literature available regarding these extremely rare tumors.

Tuberous sclerosis complex: the past and the future

Renal lesions represent the second most significant cause of morbidity and mortality in patients with tuberous sclerosis complex (TSC). Recent advances in the understanding of the pathophysiology of TSC have led to the exploration of new potential therapeutic targets. Clinical trials with mammalian target of rapamycin (mTOR) inhibitors have demonstrated promising results for several indications, such as renal angiomyolipoma, subependymal giant cell astrocytoma, lymphangioleiomyomatosis and facial angiofibromas. Currently, there is a scarcity of natural history data and randomized, placebo-controlled clinical trials on TSC. Recently, however, recommendations for the diagnostic criteria, surveillance, and management of TSC patients have been updated. This review focuses on these novel recommendations and highlights the need for multidisciplinary follow-up of this multi-systemic disease.

Renal angiomyolipoma: a radiological classification and update on recent developments in diagnosis and management

Angiomyolipoma is the most common benign solid renal neoplasm observed in clinical practice. Once thought to be a hamartoma and almost always diagnosed by the imaged-based detection of fat, angiomyolipomas are now known to consist of a heterogeneous group of neoplasms. Although all are considered perivascular epithelioid cell tumors, many display different pathology, imaging features, and clinical behavior. The importance of understanding this group of neoplasms is emphasized by the fact that many types of angiomyolipoma contain little to no fat, and despite being benign, sometimes escape a pre-operative diagnosis. These types of angiomyolipomas can all be considered when encountering a renal mass that is both hyperattenuating relative to renal parenchyma on unenhanced CT and T2-hypointense, features that reflect their predominant smooth muscle component. We review recent developments and provide a radiological classification of angiomyolipomas that helps physicians understand the various types and learn how to both diagnose and manage them.

Imaging findings of common benign renal tumors in the era of small renal masses: differential diagnosis from small renal cell carcinoma: current status and future perspectives

The prevalence of small renal masses (SRM) has risen, paralleling the increased usage of cross-sectional imaging. A large proportion of these SRMs are not malignant, and do not require invasive treatment such as nephrectomy. Therefore, differentation between early renal cell carcinoma (RCC) and benign SRM is critical to achieve proper management. This article reviews the radiological features of benign SRMs, with focus on two of the most common benign entities, angiomyolipoma and oncocytoma, in terms of their common imaging findings and differential features from RCC. Furthermore, the role of percutaneous biopsy is discussed as imaging is yet imperfect, therefore necessitating biopsy in certain circumstances to confirm the benignity of SRMs.

Angiomyolipoma

Angiomyolipomas are the most common benign tumor of the kidney and can be found in up to 1% of the general population.

Multiparametric MRI of solid renal masses: pearls and pitfalls

Functional imaging [diffusion-weighted imaging (DWI) and dynamic contrast enhancement (DCE)] techniques combined with T2-weighted (T2W) and chemical-shift imaging (CSI), with or without urography, constitutes a comprehensive multiparametric (MP) MRI protocol of the kidneys. MP-MRI of the kidneys can be performed in a time-efficient manner. Breath-hold sequences and parallel imaging should be used to reduce examination time and improve image quality. Increased T2 signal intensity (SI) in a solid renal nodule is specific for renal cell carcinoma (RCC); whereas, low T2 SI can be seen in RCC, angiomyolipoma (AML), and haemorrhagic cysts. Low b-value DWI can replace conventional fat-suppressed T2W. DWI can be performed free-breathing (FB) with two b-values to reduce acquisition time without compromising imaging quality. RCC demonstrates restricted diffusion; however, restricted diffusion is commonly seen in AML and in chronic haemorrhage. CSI must be performed using the correct echo combination at 3 T or T2* effects can mimic intra-lesional fat. Two-dimensional (2D)-CSI has better image quality compared to three-dimensional (3D)-CSI, but volume averaging in small lesions can simulate intra-lesional fat using 2D techniques. SI decrease on CSI is present in both AML and clear cell RCC. Verification of internal enhancement with MRI can be challenging and is improved with image subtraction. Subtraction imaging is prone to errors related to spatial misregistration, which is ameliorated with expiratory phase imaging. SI ratios can be used to confirm subtle internal enhancement and enhancement curves are predictive of RCC subtype. MR urography using conventional extracellular gadolinium must account for T2* effects; however, gadoxetic acid enhanced urography is an alternative. The purpose of this review it to highlight important technical and interpretive pearls and pitfalls encountered with MP-MRI of solid renal masses.

Myxolipoma of the renal capsule: A case report

INTRODUCTION

Although lipomas are the most common mesenchymal tumors of the human body, primary intrarenal lipomas are quite rare. In this report we present a case of benign mesenchymal tumor with lipomatous and myxoid components.

PRESENTATION OF CASE

A sixty one years old male patient was admitted to our outpatient clinic for a general control since he had a right radical nephrectomy operation due to renal cell carcinoma (RCC) eight years ago and he did not have any urological control for last 3 years. However the urinary ultrasound revealed a mass lesion on left kidney and then on axial contrast-enhanced computed tomography (CT) scan, there were two masses on the left kidney. In the magnetic resonance imaging (MRI), the tumor on cortex was depicted as a homogeneous low-signal intensity on the T1-weighted pulse sequence and as a heterogeneous high-signal intensity on the T2-weighted pulse sequence. In pathological evaluation, the biopsy material of the cortical mass was a tumoral lesion containing lipomatous and mixoid areas without atypia, mitosis or necrosis which was diagnosed as myxolipoma.

DISCUSSION

Myxolipoma, an uncommon type of lipoma, is a benign tumor composed mainly of fat cells with myxoid (mucus-like) components. In our case, the tumor was composed of mature adipocytes together with areas rich in mucoid substances and there were no malignant features including lipoblasts, mitosis or abundant capillary network.

CONCLUSION

Herein we present a case of a fatty tumor originating from the renal capsule with the histologic diagnosis of myxolipoma. To the best of our knowledge, myxolipoma, a very rare form of lipoma, is not reported in kidney, in the literature before.

Ten uncommon and unusual variants of renal angiomyolipoma (AML): radiologic-pathologic correlation

Classic (triphasic) renal angiomyolipoma (AML) is currently classified as a neoplasm of perivascular epithelioid cells. For diagnosis of AML, the use of thin-section non-contrast enhanced CT (NECT) improves diagnostic accuracy; however, identifying gross fat within a very small AML is challenging and often better performed with chemical-shift MRI. Although the presence of gross intra-tumoural fat is essentially diagnostic of AML; co-existing intra-tumoural fat and calcification may represent renal cell carcinoma (RCC). Differentiating AML from retroperitoneal sarcoma can be difficult when AML is large; the feeding vessel and claw signs are suggestive imaging findings. AML can haemorrhage, with intra-tumoural aneurysm size >5 mm a more specific predictor of future haemorrhage than tumor size >4 cm. Diagnosis of AML in the setting of acute haemorrhage is complex; comparison studies or follow-up imaging may be required. Not all AML contain gross fat and imaging features of AML without visible fat overlap with RCC; however, homogeneity, hyperdensity at NECT, low T2-weighted signal intensity and, microscopic fat are suggestive features. Patients with tuberous sclerosis often demonstrate a combination of classic and minimal fat AML, but are also at a slightly increased risk for RCC and should be imaged cautiously. Several rare pathological variants of AML exist including AML with epithelial cysts and epithelioid AML, which have distinct imaging characteristics. Classic AML, although benign, can be locally invasive and the rare epithelioid AML can be frankly malignant. The purpose of this review is to highlight the imaging manifestations of 10 uncommon and unusual variants of AML using pathological correlation.

Renal angiomyolipoma: a radiological classification and update on recent developments in diagnosis and management

Angiomyolipoma is the most common benign solid renal neoplasm observed in clinical practice. Once thought to be a hamartoma and almost always diagnosed by the imaged-based detection of fat, angiomyolipomas are now known to consist of a heterogeneous group of neoplasms. Although all are considered perivascular epithelioid cell tumors, many display different pathology, imaging features, and clinical behavior. The importance of understanding this group of neoplasms is emphasized by the fact that many types of angiomyolipoma contain little to no fat, and despite being benign, sometimes escape a pre-operative diagnosis. These types of angiomyolipomas can all be considered when encountering a renal mass that is both hyperattenuating relative to renal parenchyma on unenhanced CT and T2-hypointense, features that reflect their predominant smooth muscle component. We review recent developments and provide a radiological classification of angiomyolipomas that helps physicians understand the various types and learn how to both diagnose and manage them.

Robotic-assisted radical nephrectomy for renal angiomyolipoma with inferior vena cava thrombus extension

Renal angiomyolipoma with inferior vena caval venous extension is rare with only 40 cases reported in the literature. We report a case of a 35-year-old lady with angiomyolipoma with inferior vena caval thrombus that was managed surgically with robotic-assisted radical nephrectomy.

Active surveillance for renal angiomyolipoma: outcomes and factors predictive of delayed intervention

OBJECTIVE

To present the outcomes of active surveillance (AS) for renal angiomyolipomas (AMLs) and to assess the clinical features predicting delayed intervention of this treatment option.

PATIENTS AND METHODS

We retrospectively reviewed the outcomes of patients diagnosed with AMLs on computed tomography (CT) who were managed with AS at our institution. The AS protocol consisted of 6- and 12-month, then annual follow-up visits, each one including a physical examination and CT imaging. Discontinuation of AS was defined as the need or decision for an active procedure during the follow-up period. Causes of delayed intervention, as well as the type of active treatment (AT), were recorded. Clinical features at presentation of patients failing AS were compared with those who remained under AS at the time of the last follow-up. Predictive factors of delayed intervention were analysed using univariate and multivariate Cox regression models.

RESULTS

Overall, 130 patients were included in the analysis, of whom 102 (78.5%) were incidentally diagnosed, while 15 (11.5%) and 13 patients (10%) presented with flank pain and haematuria, respectively. After a mean (sd) follow-up of 49 (40) months, 17 patients (13%) discontinued AS and underwent AT. Patients who underwent delayed intervention were more likely to present with a higher body mass index, larger tumours and symptomatic disease. Angioembolization represented the first-line AT after AS (64.7%), whereas partial nephrectomy was adopted in 29.4% of patients. On the univariate analysis, risk factors for delayed intervention included tumour size ≥4 cm, symptoms at diagnosis, and history of concomitant or contralateral kidney disease. On the multivariate analysis, only tumour size and symptoms remained independently associated with discontinuation of AS.

CONCLUSIONS

Tumour size and symptoms at initial presentation were highly predictive of discontinuation of AS in the management of AMLs. Selective angioembolization was the first-line option used for AT after AS was discontinued.

Tuberous sclerosis complex surveillance and management: recommendations of the 2012 International Tuberous Sclerosis Complex Consensus Conference

BACKGROUND

Tuberous sclerosis complex is a genetic disorder affecting every organ system, but disease manifestations vary significantly among affected individuals. The diverse and varied presentations and progression can be life-threatening with significant impact on cost and quality of life. Current surveillance and management practices are highly variable among region and country, reflective of the fact that last consensus recommendations occurred in 1998 and an updated, comprehensive standard is lacking that incorporates the latest scientific evidence and current best clinical practices.

METHODS

The 2012 International Tuberous Sclerosis Complex Consensus Group, comprising 79 specialists from 14 countries, was organized into 12 separate subcommittees, each led by a clinician with advanced expertise in tuberous sclerosis complex and the relevant medical subspecialty. Each subcommittee focused on a specific disease area with important clinical management implications and was charged with formulating key clinical questions to address within its focus area, reviewing relevant literature, evaluating the strength of data, and providing a recommendation accordingly.

RESULTS

The updated consensus recommendations for clinical surveillance and management in tuberous sclerosis complex are summarized here. The recommendations are relevant to the entire lifespan of the patient, from infancy to adulthood, including both individuals where the diagnosis is newly made as well as individuals where the diagnosis already is established.

CONCLUSIONS

The 2012 International Tuberous Sclerosis Complex Consensus Recommendations provide an evidence-based, standardized approach for optimal clinical care provided for individuals with tuberous sclerosis complex.

FDG PET or PET/CT in evaluation of renal angiomyolipoma

Objective

Angiomyolipoma is the most common benign kidney tumor. However, literature describing FDG PET findings on renal angiomyolipoma (AML) is limited. This study reports the FDG PET and PET/CT findings of 21 cases of renal AML.

Materials and Methods

The study reviews FDG PET and PET/CT images of 21 patients diagnosed with renal AML. The diagnosis is based on the classical appearance of an AML on CT scan with active surveillance for 6 months. The study is focused on the observation of clinical and radiographic features.

Results

Six men and 15 women were included in our study. The mean age of the patients was 57.14 ± 9.67 years old. The mean diameter of 21 renal AML on CT scans was 1.76 ± 1.00 cm (Min: 0.6 cm; Max: 4.4 cm). CT scans illustrated renal masses typical of AMLs, and the corresponding FDG PET scans showed minimal FDG activities in the area of the tumors. None of the 21 AMLs showed a maximum standardized uptake value (SUV_max) greater than 1.98. No statistically significant correlation was present between SUV_max and tumor size.

Conclusion

Renal AMLs demonstrate very low to low uptake on FDG PET and PET/CT imaging in this study. When a fat-containing tumor in the kidney is found on a CT scan, it is critical to differentiate an AML from a malignant tumor including an RCC, liposarcoma, and Wilms tumor. This study suggests that FDG PET or PET/CT imaging is useful for differentiating a renal AML from a fat-containing malignant tumor.

Fat poor angiomyolipoma with lymphadenopathy: Diagnostic dilemma

A 24-year-old lady presented with left flank pain of 3 months duration. She had stigmata of tuberous sclerosis complex in the form of angiofibromas on face, ash-leaf macules on back and right upper limb and shagreen patches over back. Computed tomography scan of the abdomen showed 6.5 cm × 5.0 cm × 4.4 cm lobulated intensely enhancing exophytic mass lesion in mid pole of left kidney with significant para-aortic lymphadenopathy with no evidence of fat in the mass. She underwent radical left nephrectomy with a provisional diagnosis of renal cell carcinoma. Histopathological examination showed multicenteric angiomyolipoma involving kidney and para-aortic lymph nodes. This case report underscores the need for further research to differentiate fat-poor angiomyolipoma and lymphadenopathy from renal cell carcinoma.

Radiofrequency ablation (RFA) therapy for renal angiomyolipoma (AML): an alternative to angio-embolization and nephron-sparing surgery

OBJECTIVES

To show that radiofrequency ablation (RFA) is safe and effective treatment for renal angiomyolipoma (AML). Current treatments to reduce the risk of haemorrhage include tumour extirpation, angio-embolization, or ablative therapy.

PATIENTS AND METHODS

Review of our prospective database revealed 15 patients with intraoperative biopsy confirmed renal AML undergoing RFA from February 2002 to March 2010. Patients underwent either laparoscopic or computed tomography (CT)-guided percutaneous RFA using either the Cool-tip™ (Covidien, Inc. Boulder, CO, USA) or RITA™ (Angiodynamics(®), Latham, NY, USA) RFA probe. CT at 1 month, 6 months, 1 year, and annually thereafter.

RESULTS

In all, two male and 13 female patients with seven left-sided and eight right-sided tumours with a mean (range) size of 2.6 (1.0-3.7) cm underwent laparoscopic (five) or CT-guided (10) RFA. No intraoperative complications occurred. Minor complications included transient haematuria and intercostals nerve transection. Surgical complications included pneumonia and myocardial infarction. There was no radiographic evidence of persistent AML (CT enhancement) at a mean follow-up of 21 months.

CONCLUSIONS

The haemostatic effect of RFA allows renal lesions suspicious for AML to be treated without bleeding complications. Avoids surgical risk of extirpation or embolization. RFA for renal AML is safe and effective.

Diagnosis of renal angiomyolipoma with hounsfield unit thresholds: effect of size of region of interest and nephrographic phase imaging

PURPOSE

To retrospectively determine the optimal Hounsfield unit threshold and region of interest (ROI) size required to accurately diagnose renal angiomyolipoma (AML) and differentiate it from renal cell carcinoma (RCC).

MATERIALS AND METHODS

This retrospective study was institutional review board approved and HIPAA compliant, and the requirement for written informed patient consent was waived. The radiologic reports on 4502 dual-phase abdominal computed tomography (CT) examinations (nonenhanced and nephrographic phases, 5-mm collimation, 120-140 kVp, variable milliampere-second settings) performed in 2872 patients from June 2002 through October 2007 were reviewed. Solid-component masses reported as suspicious for RCC or AML were correlated with histologic and/or follow-up imaging findings. ROIs of three different sizes-tiny (8-13 mm(2)), small (19-24 mm(2)), and medium (30-35 mm(2))-were drawn in the lowest-attenuation focus on images obtained during both phases. The test characteristics (sensitivity, specificity, positive predictive value, negative predictive value, false-positive rate, false-negative rate) of multiple attenuation thresholds at each combination of ROI size and contrast enhancement phase were calculated, and receiver operating characteristic (ROC) curves were derived. Areas under the ROC curve were calculated.

RESULTS

There were 217 RCCs and 65 AMLs. With an attenuation threshold of -10 HU or lower at nonenhanced CT, RCC would be misdiagnosed as AML in 11 (5.1%) cases, one (0.5%) case, and one (0.5%) case with use of the tiny, small, and medium ROIs, respectively. With use of the tiny, small, and medium ROIs, misdiagnosis rates would be 2.3%, 0.5%, and 0.5%, respectively, at a threshold of -15 HU or lower and 1.8%, 0%, and 0%, respectively, at a threshold of -20 HU or lower. Areas under the ROC curve for the nonenhanced phase images (range, 0.874-0.889) were superior to those for the nephrographic phase images (range, 0.790-0.826).

CONCLUSION

Nonenhanced CT images were superior to nephrographic phase CT images for the diagnosis of AML. An attenuation threshold of -10 HU or lower with an ROI of at least 19-24 mm(2) is optimal for the diagnosis of AML. This threshold is not accurate with use of smaller (8-13-mm(2)) ROIs.

Benign renal angiomyolipoma with inferior vena cava thrombosis

OBJECTIVE

To present a new case of an uncommon complication of a benign renal tumor. To our knowledge, there are only few published cases of benign renal angiomyolipoma (AML) presenting with tumor thrombus in females. Epithelioid angiomyolipoma is a recently described rare variant of renal angiomyolipoma. It can occur in patients with or without tuberous sclerosis, and may potentially be malignant. Benign renal angiomyolipoma AML rarely presents with evidence of extension into the renal vein, inferior vena cava (IVC) or atrium. We report a case of a benign renal AML with a tumor thrombus to the IVC in a 46-year-old female who presented with right-sided flank pain associated with a right sided abdominal mass.

METHODS

Right Radical nephrectomy with IVC tumor thrombectomy.

RESULTS

Patient is totally asymptomatic. At 1 month after surgery, an abdominal ultrasound showed no evidence of thrombus within the IVC. CT scan of the abdomen at 3 months post-operatively showed no evidence of recurrence.

CONCLUSION

Surgical treatment of angiomyolipoma with IVC thrombus is warranted in view of risk of malignancy and to prevent tumor embolus to the heart or lungs.

Trends of presentation and clinical outcome of treated renal angiomyolipoma

PURPOSE

The purpose of this study is to set guidelines for the management of renal angiomyolipoma (AML), clinical prognosis according to tumor size, in association with tuberous sclerosis complex (TSC), multiplicity, radiographic finding, and treatment modality.

MATERIALS AND METHODS

Between March 1998 and October 2008, 129 out of 254 patients with AML who underwent surgical intervention or angioembolization were enrolled. Diagnosis of AML was determined by the presence of a low attenuated component on CT imaging or by pathological confirmation. Indications of treatment were intractable pain, hematuria, suspicion of malignancy, large tumor size, spontaneous rupture, and radiographically equivocal tumors in which a differential diagnosis was needed to rule out malignancy. Parameters including age, sex, tumor size, multiplicity, radiographic characteristics, association with TSC, and treatment modality were reviewed.

RESULTS

Age at presentation was 50.6 years and mean tumor size was 3.5 cm. Presentation symptoms were flank pain, hematuria, spontaneous rupture, and fatigue. 97 (75.2%) patients were incidentally discovered. 100 (77.5%) were females. 68 (52.7%) underwent nephron-sparing surgery (NSS), 35 (27.1%) radical nephrectomy, and 26 (20.2%) angioembolization. TSC was accompanied in 12 (9.3%) patients. No patient developed renal function impairment during the mean follow-up period of 64.8 months. Patients with TSC presented at a younger age, along with larger, bilateral, and multiple lesions.

CONCLUSION

Significant differences in clinical manifestations and treatment outcomes were noted in respect to tumor characteristics, association with TSC, and treatment modality. Considering the benign nature of AML, these parameters ought to be considered when deciding upon active surveillance or prophylactic intervention.

The radiological diagnosis and treatment of renal angiomyolipoma-current status

Angiomyolipomas (AMLs) are the most common benign renal neoplasm and are often discovered incidentally. Due to both an increase in the use of imaging, as well as advances in imaging technology, they are being increasing identified in the general population. As these lesions are benign, there is good evidence that the majority of them can be safely followed up without treatment. However, there is an increasing wealth of information available suggesting there are individuals with AMLs where prophylactic treatment is indicated to prevent complications such as haemorrhage. In such cases, treatment with radiological interventional techniques with subselective particle embolization has superseded surgical techniques in most cases. Even in emergency cases with catastrophic rupture, prompt embolization may save the patient with the additional benefit of renal salvage. Confident identification of a lesion as an AML is important as its benign nature obviates the need for surgery in most cases. The presence of fat is paramount in the confirmatory identification and characterization of these lesions. Although fat-rich AMLs are easy to diagnose, some lesions are fat poor and it is these cases where newer imaging techniques, such as in-phase and out-of-phase magnetic resonance imaging (MRI) may aid in making a confident diagnosis of AML. In this paper, we comprehensively review the imaging techniques in making a diagnosis of AML, including features of both characteristic lesions as well as atypical lesions. In addition, we discuss current guidelines for follow-up and prophylactic treatment of these lesions, as well as the increasing role that the interventional radiologist has to play in these cases.

A multi-institutional study on histopathological characteristics of surgically treated renal tumors: the importance of tumor size

PURPOSE

The incidence of accidentally detected small renal tumors is increasing throughout the world. In this multi-institutional study performed in Korea, histopathological characteristics of contemporarily surgically removed renal tumors were reviewed with emphasis on tumor size.

MATERIALS AND METHODS

Between January 1995 and May 2005, 1,702 patients with a mean age of 55 years underwent surgical treatment at 14 training hospitals in Korea for radiologically suspected malignant renal tumors. Clinicopathological factors and patient survival were analyzed.

RESULTS

Of the 1,702 tumors, 91.7% were malignant and 8.3% were benign. The percentage of benign tumors was significantly greater among those < or = 4 cm (13.2%) than those > 4 cm (4.5%) (p < 0.001). Among renal cell carcinoma patients, the percentage of tumors classed as stage > or = T3 was significantly less among tumors < or = 4 cm (5.2%) than those > 4 cm (26.8%) (p < 0.001). The percentage of tumors classed as Fuhrman's nuclear grades > or = 3 was also significantly less among tumors < or = 4 cm (27.3%) than tumors > 4 cm (50.9%) (p < 0.001). The 5-year cancer-specific survival rate was 82.7%, and T stage (p < 0.001), N stage (p < 0.001), M stage (p = 0.025), and Fuhrman's nuclear (p < 0.001) grade were the only independent predictors of cancer-specific survival.

CONCLUSION

In renal tumors, small tumor size is prognostic for favorable postsurgical histopathologies such as benign tumors, low T stages, and low Fuhrman's nuclear grades. Our observations are expected to facilitate urologists to adopt function-preserving approach in the planning of surgery for small renal tumors with favorable predicted outcomes.

[Differential diagnosis of changes in kidney tumors of a small size]

The paper is aimed at presenting several patients treated at the CCS Institute of Urology and Nephrology using the retrospective analysis, in whom differentiation of the kidney tumor change nature and size smaller than 3 cm were decisive for further treatment. Similar cases were not reported or were reported exceptionally rarely in the literature. The diagnosis was established based on ultrasound examination, intravenous urography, computed tomography, magnetic resonance imaging as well as angiography, percutaneous biopsy and pathohistological analysis of the surgical preparation.

[Renal imaging and biopsy for diagnosis of renal masses]

Incidental diagnosis of renal tumors is more and more common. Imaging is of paramount importance for the caracterization of these tumors. Ultrasound allows the diagnosis of solid tumors, thereby excluding cysts. The gold standard is the CT-scan, the realisation of which must obey to precise quality criteria. MRI yields further informations in selected cases. Renal cancer is the main etiology, but benign tumors can be suspected in small tumors less than 4 cm. Angiomyolipoma and oncocytoma are the more frequent benign tumors. Angiolipoma can be diagnosed with CT-scan, but there are no radiological criteria for the diagnosis of oncocytoma. Renal percutaneous biopsy can be helpful in selected cases. It is recommended for bilateral tumors, or when a renal metastasis is suspected. For small lesions with radiological features consistent with the diagnosis of benign tumor, renal biopsy can confirm this diagnosis and lead surgical abstention. Nevertheless, few centers have a regular practise of renal biopsy. Its contribution is still to be evaluated.

Oncologic Emergencies

It has been estimated that genitourinary malignancies will account for 25% of new cancer diagnoses in the United States in 2005 (Jemal et al. 2005). While the incidence of many of these malignancies has increased over the past two decades, the mortality rates appear to be decreasing. Early cancer detection combined with improvements in surgical and nonsurgical oncologic therapy account for these trends. Although not common, newly diagnosed cancer patients occasionally present in an emergent, life-threatening manner that warrants immediate medical or surgical intervention. As the prevalence of genitourinary malignancies continues to expand, additional patients can be expected to develop disease or treatment-related complications. This chapter will serve to review the diagnosis and management of oncologic emergencies as they pertain to the urologist.

Retroperitoneal haemorrhage caused by a renal angiomyolipoma

Renal angiomyolipoma (AML) is a benign renal tumour and is nowadays considered a relatively common lesion. When an AML increases in size or becomes symptomatic, embolisation via the renal artery should then be considered, because rupture is an important complication and interventional therapies are required to stop bleeding. We present a 21 year old woman who was seen at the emergency department following a low velocity trauma. After a period of 9 weeks, clinical examination and radiological examination revealed a haemorrhage from a renal AML, which was treated by selective embolisation. A discussion of the relevant literature is also presented.

Fat poor renal angiomyolipoma: patient, computerized tomography and histological findings

PURPOSE

We reviewed our experience with fat poor cases of angiomyolipoma.

MATERIALS AND METHODS

The records of patients with angiomyolipoma, as determined by pathological study, from 1998 to 2004 were reviewed by recording patient demographics and outcomes. Fat poor cases were defined as the failure of imaging to demonstrate fat in a lesion. Computerized tomography and histological characteristics were assessed.

RESULTS

Histologically confirmed angiomyolipoma was found in 15 patients. Multiple lesions were found in 3 of 15 cases (20%). Of these 15 patients who underwent surgery 11 (73%) had unsuspected angiomyolipoma due to absent fat on computerized tomography and they underwent intervention for presumed renal cell carcinoma. Mean age +/- SD in this group was 54 +/- 15 years and 8 of 11 patients (73%) were female, of whom 4 (50%) had uterine fibroids. These lesions were found incidentally in 7 of 11 cases (64%). Operative complications developed in 2 of 11 patients (18%). Average maximal diameter on pathological evaluation was 3.2 +/- 1.3 cm (range 1.5 to 6). Nonenhanced computerized tomography was available in 7 of 11 cases, of which 3 of 7 (42%) showed hyperdense lesions and 4 of 7 (57%) showed isodense lesions. The percent of fat identified per high power field was less than 25% in 12 of 13 fat poor angiomyolipoma lesions (92%) compared to 2 of 4 classic lesions (50%) known to be angiomyolipoma before surgery (p = 0.04).

CONCLUSIONS

We suggest that a general definition of fat poor angiomyolipoma should be the failure of imaging to reveal fat within a lesion, thus, making it unsuspected at surgery. A pathological definition should be less than 25% fat per high power field, which to our knowledge is a formerly undefined quantity. Not all cases are hyperdense on nonenhanced computerized tomography. These lesions cannot be reliably identified by imaging and they should be managed like all enhancing renal masses.

Large renal angiomyolipomas: digital subtraction angiographic grading and presentation with bleeding

AIM

To investigate whether a grading system of renal AMLs based on digital subtraction angiography (DSA) and computerized tomography (CT), could help to select patients for embolization.

MATERIALS AND METHODS

Thirty patients with 35 renal angiomyolipomas (size range 4-20 cm, mean 9.9 cm) underwent both digital subtraction angiography (DSA) and computed tomography (CT). Based on the DSA appearance the tumours were graded into three grades: grade I, minimal vascularity; grade II, moderate vascularity; grade III, marked vascularity.

RESULTS

There were seven grade I (mean 9.3 cm, range 4.5-20 cm), 18 grade II (mean 8.9 cm, range 5-18 cm) and 10 grade III tumours (mean 12.1 cm, range 4-20 cm). Five grade I tumours did not cause symptoms (71%) and two caused flank pain and haematuria, respectively (14.3% each). Nine of the grade II tumours were asymptomatic (50%), seven caused bleeding (39%) and two caused flank pain (11%). Four grade III tumours were asymptomatic (40%), five caused bleeding (50%) and one pain (10%).

CONCLUSIONS

According to our criteria, large angiomyolipomas with minimal vascularity are less likely to bleed, and do not need prophylactic treatment. This needs to be confirmed in larger studies.

Diagnosis of angiomyolipoma using computed tomography—region of interest ≤−10HU or 4 adjacent pixels ≤−10HU are recommended as the diagnostic thresholds

AIM

To study and compare the diagnostic accuracy of region of interest (ROI) density measurement and pixel mapping [computed tomography (CT) density of individual pixels] for the diagnosis of renal angiomyolipoma (AML) using CT.

MATERIALS AND METHODS

A study group of histologically proven AMLs was compared with a control group of histologically proven renal cell cancers, normal renal parenchyma, and simple renal cysts. The mean tissue density (ROI circle) and a pixel density map were recorded. The diagnostic accuracy of various thresholds of ROI and pixel mapping values were compared using receiver operating characteristic curves.

RESULTS

Twenty-two AMLs, 16 renal cell carcinomas (RCCs), 30 simple cysts, and 30 sites of renal parenchyma were evaluated. The mean (+/-1 SD) density of the AMLs was significantly lower [-15.2(20.8) units] than the three control groups [+36.0(8.1) units, +5.4(3.4) units and +22.2(46.5) units for RCC, renal cyst and parenchyma respectively; p < 0.001 (analysis of variance)]. The sensitivities and specificities of the ROI diagnostic thresholds of < or =0 units, < or =-10 units and < or =-20 units were 77 and 97%, 73 and 100% and 50 and 100%, respectively. Using pixel mapping [diagnostic thresholds of either a line of 4 pixels < or =-10 units or a square of 4 pixels < or =-10 units] the sensitivity improves to 86% with a specificity of 97%.

CONCLUSION

Although a ROI threshold value of < or =-10 units has a very high specificity (100% in the present study) the sensitivity is modest at only 73%. Pixel mapping is more sensitive for recognizing small clusters of fat. In practice, both methods can be recommended for the analysis of suspected AMLs. ROI density measurement is convenient when analysing large areas of suspected fat and < or =-10 units should be used as the diagnostic threshold. When faced with small lucent areas or indeterminate values after ROI analysis, pixel mapping is recommended using a line of 4 pixels < or =-10 units or a square of 4 pixels < or =-10 units as the discriminating thresholds.