CT and MRI Findings of Renal Angiomyolipoma With Lung Metastasis: A Case Report and Literature Review.

Renal angiomyolipoma has two histological variants: classical and epithelioid. Epithelioid angiomyolipoma is considered as a potential malignant tumor, often leading to recurrence and metastasis, with rapid progression in most of the cases. The lung is one of the most commonly reported sites of metastasis, and pulmonary metastasis of renal angiomyolipoma is usually diagnostic by computed tomography (CT) scans. Here, we report for the first time renal angiomyolipoma with lung metastasis by combining CT and magnetic resonance imaging (MRI).

Utility of Chemical Shift Imaging and Diffusion-weighted Images/Apparent Diffusion Coefficient Maps as a Tool for Evaluation of Solid Renal Tumors.

OBJECTIVES: To study the utility of chemical shift imaging (CSI) and diffusion-weighted images (DWI)/apparent diffusion coefficient (ADC) maps for the evaluation of solid renal tumors. METHODS: Magnetic resonance imaging (MRI) has an equivalent application as computerized tomography (CT) in the characterization of renal masses. It offers a radiation-free imaging technique and has a better soft tissue contrast than CT. Also, MRI is favored in patients with chronic kidney disease. MRI is useful when findings on CT are equivocal. The role of DWI in characterizing solid renal lesions as malignant is encouraging, and DWI can be particularly useful when gadolinium is contraindicated. CSI is useful in differentiating angiomyolipoma (AML) from clear cell (cc) renal cell carcinoma (RCC). We did a cross-sectional study on 24 patients with solid renal masses. MRI of the upper abdomen (from the dome of the diaphragm to the iliac crest) will be done on an MRI machine in our department (1.5T, ACHIEVA, Phillips medical system) using the torso coil. RESULT: There was no significant association seen in terms of ADC values and histological subtypes (χ2 = 11.222, p = 0.082). In our study, 50% (one out of two) of AML showed a signal drop, whereas 40% of cases (6 out of 15) of ccRCC and 66% (two out of three) of papillary RCC showed a signal drop. CONCLUSION: In this article, we concluded CSI, although a useful tool to look for microscopic fat, can't be used as a reliable marker to rule in cc-carcinoma as both AML and papillary cell carcinoma have microscopic fat. Further, no histological classification can be done on the basis of DWI/ADC images.

High-frame-rate contrast-enhanced ultrasound to differentiate between clear cell renal cell carcinoma and angiomyolipoma.

BACKGROUND: To investigate the diagnostic efficacy of high-frame-rate contrast-enhanced ultrasound (H-CEUS) in differentiating between clear cell renal cell carcinoma (CCRCC) and angiomyolipoma (AML). METHODS: A retrospective study was performed on the clinical data of 79 patients diagnosed with CCRCC and 31 patients diagnosed with AML at the First Affiliated Hospital of Nanchang University between October 2022 and December 2023. Conventional ultrasound (US) and H-CEUS examinations were conducted on all patients prior to surgery, dynamic images were recorded from the US, and the qualitative and quantitative parameters of H-CEUS were collected. The t-test, χ² test and non-parametric Mann-Whitney test were employed to assess differences in clinical data, US characteristics, and qualitative and quantitative parameters of H-CEUS between the CCRCC and AML groups. The independent risk factors of CCRCC were identified using binary logistic regression. The receiver operator characteristic (ROC) curve was constructed to evaluate the diagnostic effectiveness of clinical + US and H-CEUS in differentiating between CCRCC and AML. RESULTS: The CCRCC group and the AML group exhibited significant differences in patient gender, operation mode, nodular echo, and nodule blood flow (χ²=11.698, -, -,=10.582; P<0.001, <0.001, <0.001, and = 0.014, respectively). In addition, the H-CEUS qualitative analysis demonstrated significant differences between the AML group and the CCRCC group with respect to enhancement mode, regression mode, peak intensity, enhancement uniformity, no enhancement, and presence or absence of pseudocapsule (χ²=41.614, -, -, = 2.758, = 42.099, -; P<0.001, <0.001, <0.001, 0.097, <0.001, and <0.001, respectively). The Arrival time (AT) in the CCRCC group was significantly shorter than that in the AML group, as determined by quantitative analysis of H-CEUS (Z=-3.266, P = 0.001). Furthermore, the Peak intensity (PI), Ascent slope (AS), and The area under the curve (AUC) exhibited significantly higher values in the CCRCC group compared to the AML group (Z=-2.043,=-2.545,=-3.565; P = 0.041, = 0.011, and <0.001, respectively). Logistic regression analysis indicated that only gender, nodule echo, the pseudocapsule, AS, and AUC of H-CEUS were independent risk factors of CCRCC. The ROC curve revealed that combining gender and nodule echo yielded a sensitivity of 92.4%, specificity of 64.5%, and an AUC of 0.847 in distinguishing between CCRCC and AML. When combining the H-CEUS parameters of pseudocapsule, AS, and AUC, the sensitivity, specificity, and AUC for distinguishing between CCRCC and AML were 84.8%, 96.8%, and 0.918, respectively. No statistically significant difference was observed in the diagnostic effectiveness of the two methods (Z=-1.286, P = 0.198). However, H-CEUS demonstrated better AUC and specificity. CONCLUSIONS: H-CEUS enhances the sensitivity and specificity of differentiating between CCRCC and AML by improving the temporal resolution, offering a more precise diagnostic foundation for identifying the most appropriate therapy for patients.

Management of Nontraumatic Spontaneous Renal Hemorrhage (Wünderlich Syndrome) through Robotic-Assisted Laparoscopic Nephrectomy: A Case Series.

BACKGROUND Wünderlich syndrome (WS) is a rare diagnosis of nontraumatic spontaneous renal hemorrhage into the subcapsular, perirenal, or pararenal spaces. Prompt and effective intervention is necessary for an accurate pathological diagnosis and preservation of life. In the current literature, open surgery is the primary option when conservative treatment fails, but there can be serious trauma and corresponding consequences. Herein, we present 3 cases of Wünderlich syndrome managed by robot-assisted laparoscopic nephrectomy via a retroperitoneal approach. CASE REPORT Patient 1 was a 44-year-old woman with right flank pain for 6 h. Patient 2 was a 53-year-old woman with a history of diabetes who had pain in her right flank pain and nausea for 1 day. Patient 3 was a 45-year-old man with left flank pain for 1 day. All cases of WS were confirmed by CT. All 3 patients were treated with retroperitoneal robot-assisted nephrectomy after conservative treatment failed. Pathological examination confirmed that patient 1 had angiomyolipoma, and patients 2 and 3 had renal clear cell carcinoma. At the 9-month follow-up, renal function was good and no evidence of recurrence or metastasis has been detected. CONCLUSIONS These cases have highlighted the importance of the clinical history and imaging findings in the diagnosis of Wünderlich syndrome, and show that rapid management can be achieved using robot-assisted laparoscopic nephrectomy. However, it is crucial to have a skilled surgical team and adequate preoperative preparation.

Stepwise algorithm using computed tomography and magnetic resonance imaging for differential diagnosis of fat-poor angiomyolipoma in small renal masses: A prospective validation study.

OBJECTIVES: To validate the diagnostic accuracy of a stepwise algorithm to differentiate fat-poor angiomyolipoma (fp-AML) from renal cancer in small renal masses (SRMs). METHODS: We prospectively enrolled 223 patients with solid renal masses <4 cm and no visible fat on unenhanced computed tomography (CT). Patients were assessed using an algorithm that utilized the dynamic CT and MRI findings in a stepwise manner. The diagnostic accuracy of the algorithm was evaluated in patients whose histology was confirmed through surgery or biopsy. The clinical course of the patients was further analyzed. RESULTS: The algorithm classified 151 (68%)/42 (19%)/30 (13%) patients into low/intermediate/high AML probability groups, respectively. Pathological diagnosis was made for 183 patients, including 10 (5.5%) with fp-AML. Of these, 135 (74%)/36 (20%)/12 (6.6%) were classified into the low/intermediate/high AML probability groups, and each group included 1 (0.7%)/3 (8.3%)/6 (50%) fp-AMLs, respectively, leading to the area under the curve for predicting AML of 0.889. Surgery was commonly opted in the low and intermediate AML probability groups (84% and 64%, respectively) for initial management, while surveillance was selected in the high AML probability group (63%). During the 56-month follow-up, 36 (82%) of 44 patients initially surveyed, including 13 of 18 (72%), 6 of 7 (86%), and 17 of 19 (89%) in the low/intermediate/high AML probability groups, respectively, continued surveillance without any progression. CONCLUSIONS: This study confirmed the high diagnostic accuracy for differentiating fp-AMLs. These findings may help in the management of patients with SRMs.

Renal Collision Tumor: A Case of Small Cell Lung Cancer Metastasis to Renal Angiomyolipoma.

ABSTRACT: A 68-year-old woman presented with chest pain and shortness of breath. Imaging revealed a left hilar mass biopsy-proven as small cell cancer. Concurrently, a macroscopic fat-containing renal lesion consistent with an angiomyolipoma was observed. Systemic therapy achieved stability in the lungs and bones, and palliative radiation targeted the left hilum. However, progressive lung disease and brain metastases necessitated stereotactic radiosurgery for brain lesions. Notably, the renal angiomyolipoma exhibited increased soft tissue component and new focal uptake on FDG PET/CT. Biopsy confirmed metastatic small cell lung cancer within the renal lesion. This case highlights a rare occurrence of a renal collision tumor involving small cell cancer and angiomyolipoma.

Spontaneous rupture of renal angiomyolipoma in pregnancy mimicking preterm labour.

Ruptured renal angiomyolipoma in pregnancy is uncommon. Pregnant women may present with nonspecific symptoms such as flank or abdominal pain, contraction pain and haematuria. A thorough assessment is needed to reach the correct diagnosis. Management varies between conservative measures, radiological intervention or surgery depending on the patient's haemodynamic status and foetal condition. We present a case of a woman in her 30s, gravida 5 para 3+1 at 28 weeks of gestation, who presented with pain. The pain worsened, and she went into hypovolaemic shock. An exploratory laparotomy and emergency caesarean section were done. Retroperitoneal haematoma was found intraoperatively, but the source of bleeding was difficult to determine. An abdominal CT angiogram subsequently revealed an ongoing bleeding from a ruptured angiomyolipoma. An emergency nephrectomy was performed, and the bleeding was secured.

The association between computed tomography attenuation value of renal angiomyolipoma associated with tuberous sclerosis complex and response to everolimus.

BACKGROUND: The response to everolimus in patients with renal angiomyolipoma associated with tuberous sclerosis complex (TSC-RAML) varies among individuals. This study aims to identify potential factors associated with the response to everolimus. METHOD: We retrospectively examined data encompassing age, gender, tumor size, computed tomography attenuation value (CT value), CT enhancement, and tumor reduction rate in patients with TSC-RAML undergoing everolimus in two previously registered clinical trials. RESULT: A total of 33 participants (29.33 ± 6.63 years old, 20 females) were included. The correlation analysis conducted separately for tumors located in the left and right kidneys revealed significant negative correlations (P < 0.05) between tumor reduction rate and age, as well as tumor size. While significant positive correlations (P < 0.05) were observed between tumor reduction rate and unenhanced CT value as well as CT enhancement. Nonetheless, based on multiple linear regression analysis, unenhanced CT value emerged as the sole-independent predictor of tumor reduction rate among age, gender, tumor size, unenhanced CT value and CT enhancement for both left (coefficient = 0.00319, P < 0.0001) and right kidneys (coefficient = 0.00315, P = 0.0104). Notable reductions were observed in unenhanced CT value (- 3.81 vs - 24.70HU, P < 0.0001) and CT enhancement (48.16 vs 33.56HU, P < 0.0001) following a 3-month administration of everolimus. The decline in both unenhanced CT value and tumor size predominantly occurred within the initial 3 months, subsequently maintaining a relatively stable level throughout the treatment. CONCLUSION: The unenhanced CT value of TSC-RAML showed an independent correlation with the response to everolimus, suggesting its potential as a predictor of everolimus efficacy in patients with TSC-RAML.

Qualitative and quantitative characteristics of CEUS for renal cell carcinoma and angiomyolipoma: a narrative review.

Incidental findings of renal masses are increasing. However, a substantial portion of surgically treated renal masses turn out to be benign on histopathological examination. Thus, there is a clear need for improved pre-surgical assessment to minimize unnecessary invasive procedures. The challenge intensifies when distinguishing between renal cell carcinoma (RCC) and angiomyolipoma (AML) in renal lesions smaller than 4 cm with minimal adipose tissue. In such cases, contrast-enhanced ultrasound (CEUS) has emerged as a valuable diagnostic tool, by utilizing both qualitative and quantitative parameters. Quantitative measures offer objectivity, reliability, and reproducibility compared to qualitative parameters, enabling the characterization of RCC subtypes and differentiation from AML. Qualitative features as enhancement pattern, degree, and peak were less helpful in distinguishing triphasic minimal fat AML (TAML) from epithelioid AML (EAML), with the pseudocapsule sign potentially being the only distinguishing qualitative feature. The pseudocapsule sign was more frequently observed in ccRCCs (38.0%) than in AMLs (15.6%). Moreover, it was detected in 40.0% of EAMLs and 34.5% of ccRCCs but not in TAMLs due to similar growth patterns between EAMLs and low-grade ccRCCs. Quantitative measures such as the time-to-peak (TTP) ratio can further enhance diagnostic accuracy and also TOC ratio should be considered, as it was higher in clear cell RCCs (ccRCCs) and in EAMLs compared to TAMLs, indicating behavior similar to ccRCCs. However, CEUS remains an operator-dependent exam.

Natural history of renal angiomyolipoma in a high-volume center: our experience during more than 15 years of follow up.

OBJECTIVES: To describe the natural history of AML, the clinical results and the need for treatment during long-term follow-up of renal AML. METHODS: Retrospective study of patients diagnosed with AML by computed tomography or nuclear magnetic resonance between 2001 and 2019, with at least two follow-up images. Clinical and imaging variables, need for intervention, complications and follow-up time were recorded. Statistical analysis was performed using SPSS 22.0. RESULTS: 111 patients and 145 AML were included. The median follow-up was 6.17 years (range 0.7-18.1, IQR 11.8-12.2). The median tumor size at diagnosis was 13 mm (IQR 7.5-30), with 24 (16.4%) being ≥ 4 cm. Most presented as an incidental finding (85.5%); in 3 (2.1%) cases, the presentation was as a spontaneous retroperitoneal hematoma. The main indication for intervention was size ≥ 4 cm in 50%. Eighteen (12%) patients received a first intervention, being urgent in 3. Embolization was performed in 15 cases and partial nephrectomy in 3. The need for reintervention was recorded in five: two underwent partial nephrectomy and two total nephrectomy; one patient required a new urgent embolization. Of the non-operated patients, 43% decreased in size or did not change, while 57% increased, with the median annual growth being 0.13 mm (IQR - 0.11 to 0.73). There were no differences in the median growth in tumors measuring ≥ 4 cm (0.16 mm) at diagnosis vs. < 4 cm (0.13 mm) (p = 0.9). CONCLUSIONS: The findings of this study suggest that AML typically demonstrate a slow-progressing clinical course during long-term follow-up. Moreover, our observations, which cast doubt on tumor size as a reliable predictor of adverse clinical outcomes, advocate for a less intensive monitoring strategy in both monitoring frequency and choice of imaging modality.

Renal angiomyolipoma: from imaging to intervention.

A high volume of cross-sectional imaging has created a window of opportunity for radiologists to identify renal angiomyolipomas (AMLs). The purpose of this review is to help the reader recognise the spectrum of renal AML appearances using different imaging methods and to gain an understanding of the classic and atypical features for appropriate lesion characterisation. Risk factors for AML growth and rupture will be highlighted. An overview of the imaging features of acute AML rupture will be provided, principally relating to computed tomography (CT) assessment. A series of cases will be presented, including a case of peripartum renal AML rupture during Caesarean section leading to diagnostic dilemma. The indications for intervention and available treatment options will be considered: medical therapy, surgery, and interventional radiology (IR) techniques including their pros and cons. Emergency interventional radiology management with selective transarterial embolisation will be presented and analysed in relation to technique, angiographic appearances (pre and post embolisation) and associated complications.

Role of Contrast-Enhanced Ultrasound With the Enhancement Pattern and Qualitative Analysis for Differentiating Hypovascular Solid Renal Lesions.

OBJECTIVE: The aim of the work described here was to explore the clinical value of contrast-enhanced ultrasound (CEUS) with the enhancement pattern and qualitative analysis in distinguishing different types of hypovascular solid renal lesions. METHODS: A total of 140 patients with 140 renal tumors (all diagnosed by pathology), which manifested hypo-enhancement on CEUS, were included in this study. We compared conventional ultrasound (US) and CEUS features in five common hypovascular renal tumors, including renal angiomyolipoma (RAML), clear cell renal cell carcinoma (ccRCC), renal pelvic urothelial carcinoma (RPUC), papillary renal cell carcinoma (pRCC) and chromophobe renal cell carcinoma (chRCC). The diagnostic value of conventional US and qualitative parameters of CEUS for differentiating hypovascular solid renal lesions were evaluated. RESULTS: The mean age of patients with a benign renal lesion was younger than that of patients with a malignant renal lesion (p < 0.05). Echogenicity and qualitative parameters such as wash-out, perfusion defects and perilesional rim-like enhancement (PRE) in the two groups differed significantly (all p values <0.05). Benign renal lesions exhibited mainly slow wash-out, whereas malignant renal lesions exhibited predominantly fast wash-out on CEUS (p < 0.05). There were significant differences in echogenicity, such as between RAML and ccRCC, between RAML and RPUC and between RAML and pRCC (all p values <0.05). The rates of appearance of perfusion defect in ccRCC (48%, 13/27) and pRCC (53%, 10/19) were significantly higher than the rate in RAML (14%, 6/43) (p < 0.05). The rates of appearance of PRE in ccRCC (15%, 4/27), pRCC (26%, 5/19) and chRCC (24%,4/17) were significantly higher than the rate in RAML (9%, 4/43) (p < 0.05). CONCLUSION: CEUS with the enhancement pattern and qualitative analysis may be helpful in distinguishing malignant from benign hypovascular renal lesions.