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Mechanistic target of rapamycin kinase (mTOR) is a member of the phosphatidylinositol-3-hydroxide kinase (PI3 K)-related protein kinase family that functions as a central regulator of cell growth, metabolism, proliferation, and survival. The role of the TSC-mTOR signaling pathway in kidney tumors has been implicated in some hamartoma syndromes; however, with the advent and wide utilization of molecular studies, a growing number of kidney tumors have been linked to somatic or germline mutations involving genes that encode for this pathway, including eosinophilic solid and cystic renal cell carcinoma, low-grade oncocytic tumor, eosinophilic vacuolated tumor, renal cell carcinoma with fibromyomatous stroma and angiomyolipoma, among others. Herein, we review the contemporary developments of mTOR pathway-related renal neoplasia, focusing on the clinicopathologic features of the tumor entities. [ABSTRACT FROM AUTHOR]

Introduction. Angiomyolipoma (AML) is a mesenchymal neoplasm that belongs to the perivascular epithelioid cell tumor family (PEComa). AMLs can be subtyped into several patterns dependent on cell type, morphology, and tissue composition. One of the patterns, oncocytoma-like AML is a rare entity with only three cases published in the literature. Case presentation. We present a case of a previously healthy 29-year-old woman who underwent a left partial nephrectomy secondary to a 4.6 cm heterogeneous renal neoplasm. Gross examination demonstrated a well-circumscribed renal mass. Modified Giemsa stain preparation showed oncocytic cells in syncytial pattern with ample granular cytoplasm and round nuclei with prominent nucleoli. Histology assessment showed an oncocytic neoplasm with interspersed adipose tissue. The tumor exhibited tubular architecture with the tubules lined by eosinophilic epithelioid cells with nuclear atypia and prominent nucleoli. Thick blood vessels with emanating epithelioid cells were present. High-grade histology features were not identified. The tumor cells were positive for HMB-45 and SMA and negative for PAX8, keratins, KIT, and vimentin. A diagnosis of oncocytoma-like AML was rendered. Next-generation sequencing (NGS) and RNA fusion were performed. NGS revealed no pathogenic variants and RNA fusion identified no rearrangements. Chromosomal copy number alterations were present in the long arm of chromosome 1 (1p) and chromosome 22. Conclusions. We describe and discuss the clinical, cytomorphologic, histologic, and molecular findings of oncocytoma-like AML, a rare renal neoplasm, and provide a review of the literature. [ABSTRACT FROM AUTHOR]

The article describes a case of TSC2/PKD1 contiguous gene deletion syndrome in a pediatric patient, presenting with retinal hamartomas, seizures, renal cysts, nasal angiofibromas, and cardiac rhabdomyomas. Topics include the clinical manifestations and diagnostic challenges of contiguous gene deletion syndrome, the importance of genetic testing in complex pediatric cases, and the need for comprehensive literature review to guide diagnosis and therapy.

Renal epithelioid angiomyolipoma (EAML) (epithelioid PEComa of the kidney), is a rare subtype of renal angiomyolipoma with the potential for aggressive behavior and a known diagnostically challenging entity. We present a renal EAML with unusual papillary architecture and tumor cells with abundant eosinophilic cytoplasm and cherry-red nucleoli with perinucleolar halos, strongly mimicking a fumarate hydratase (FH) deficient renal cell carcinoma (RCC). We herein report our findings and discuss the morphologic, immunohistochemical, and molecular pitfalls to consider in the differential of EAML, including with FH-deficient RCC and more recently described entities: TFEB -amplified RCC and other renal tumors with alterations in TSC1/2. Novel findings in this tumor include papillary morphology and a novel telomerase reverse transcriptase promoter rearrangement, which has not been previously reported in EAML. [ABSTRACT FROM AUTHOR]

Angiomyolipoma is a benign, mesenchymal, hamartomatous lesion often described in the kidney and may be associated with tuberous sclerosis. Nasal angiomyolipoma is an extremely rare tumor with fewer than 20 cases reported in the literature. We report a case of angiomyolipoma arising in the right nasal vestibule in a 68-year-old male with mild, recurrent right-sided epistaxis, and nasal obstruction. With the exception of arterial hypertension, the patient did not have any comorbidities. Gross examination showed a well-circumscribed, lobulated mass. On the microscopic level, it was composed of mature smooth muscle cells, thick-walled blood vessels of varying sizes, and islands of mature adipose tissue. Angiomyolipoma should be considered as a differential diagnosis for unilateral nasal masses, especially those situated in the nasal vestibule. [ABSTRACT FROM AUTHOR]

Background: The extent of renal angiomyolipoma (AML) volume reduction after renal transcatheter arterial embolization (TAE) varies between patients, with no predictive measure available. Purpose: To determine whether the serum lactate dehydrogenase (LDH) concentration shortly after TAE correlates with the extent of tumor shrinkage. Material and Methods: In a cohort of 36 patients undergoing prophylactic renal TAE for unruptured renal AML, we retrospectively acquired data from patient medical records, including serum LDH before and within 7 days after TAE and the tumor volume before and 12–36 months after TAE. The relationship between the serum level of LDH and reduction in tumor volume was evaluated using Spearman correlation analysis. Results: The median LDH concentration was significantly higher after TAE than before (909.0 U/L vs. 186.5 U/L). This early post-TAE serum LDH level and LDH index (post-TAE LDH / pre-TAE LDH) correlated significantly and positively with the absolute decrease in tumor volume (both P < 0.0001). We observed no significant correlation between the relative tumor volume reduction and serum LDH level or LDH index. Conclusion: Serum LDH elevation occurs shortly after TAE and correlates with the extent of absolute decrease in AML volume at 12–36 months after TAE. Further large-scale studies are warranted to confirm the predictive role of post-TAE serum LDH level and LDH index in tumor shrinkage in patients with unruptured renal AML. [ABSTRACT FROM AUTHOR]

Background: Acute myeloid leukemia (AML) is the most common type of acute leukemia in adults. Bone marrow computed tomography (CT) attenuation may increase in patients with myeloproliferative disorders; however, the actual threshold CT attenuation value predictive of myeloproliferative has not been reported. Purpose: To determine whether the unenhanced CT attenuation value of the bone marrow may be useful for predicting AML. Material and Methods: We retrospectively analyzed patients with AML (n = 56) who underwent unenhanced CT before treatment, and age- and sex-matched controls without any hematologic disease. For each patient, the CT attenuation value (HU) of the iliac bone was measured and compared between the two groups. Receiver operating characteristic (ROC) curve analysis was used to define the cutoff value for predicting AML on all patients, and only on late elderly patients (aged ≥75 years). Results: Patients with AML showed higher bone marrow CT attenuation value (131.4 ± 58.3 vs. 53.9 ± 67.2 HU; P < 0.001), compared to the controls. The sensitivity and specificity for the diagnosis of AML in all patients were 78.6% and 80.4%, respectively, at a threshold value of 90 HU, whereas they were 83.3% and 91.7%, respectively, at 40 HU in late elderly patients. Conclusion: The iliac bone CT attenuation value was elevated in patients with AML and may be useful for predicting AML. [ABSTRACT FROM AUTHOR]

Background: Detection and characterization of renal lesions are common in daily clinical practice. Purpose: To investigate the effectiveness of shear wave elastography (SWE), a novel radiological examination technique, in the characterization of renal masses. Material and Methods: The study included a total of 68 patients (33 men, 35 women; mean age = 57.71 ± 12.08 years; age range = 19–83 years) who underwent SWE. SWE measurements were obtained at depths of 2–8 cm from the probe surface in two different positions from an analysis window of approximately 0.5 × 1.0 cm on ultrasound. The cutoff SWE was calculated for the differentiation of renal cell carcinoma (RCC) and angiomyolipoma (AML) by receiver operating characteristic (ROC) analysis. When the result was statistically significant, the sensitivity, specificity, accuracy, and positive and negative predictive values of the test were calculated. Results: Mass-to-parenchyma SWE ratios of RCCs were significantly higher than those of AMLs (P = 0.003). In ROC curve analysis, the SWE cutoff was 1.215 m/s to differentiate RCCs from AMLs. The area under the ROC curve was calculated as 0.74 (95% CI = 0.610–0.871, sensitivity = 70.7%, specificity = 70.6%, positive predictive value = 87.8%, negative predictive value = 44.4%). Conclusion: The SWE technique is increasingly used and may be useful in distinguishing RCC and AML lesions, and especially clear cell and non-clear cell RCCs. [ABSTRACT FROM AUTHOR]

Background: Contrast-enhanced spectral mammography (CESM) may help to determine the malignancy potential of lesions according to the degree of enhancement. Purpose: To investigate the correlation between the degree of contrast enhancement of the lesions in contrast-enhanced spectral mammography (CESM) and the final histopathological diagnosis in patients with BI-RADS 4 and 5 lesions. Material and Methods: CESM was performed in 128 patients who had BI-RADS 4 and 5 lesions on mammography and underwent histopathological examination. A total of 128 index lesions were scored using a 4-point scale regarding the degree of contrast enhancement (0 = no contrast enhancement, 1 = minimal, 2 = moderate, 3 = marked), a score of 2 and 3 was accepted as suggestive of malignancy. The study was approved in our institutional scientific committee. Results: In total, 76 (59.4%) of the lesions had benign histopathological results, whereas 52 of them had malignant results. Contrast enhancement was not observed in 22.7% of the lesions while 24.2% had minimal enhancement, 18.8% had moderate enhancement, and 34.4% had marked enhancement in CESM. The sensitivity of the degree of contrast enhancement in CESM was 98.1%, when the specificity was 77.6%, positive predictive value was 75%, negative predictive value was 98.3%, and accuracy was 85.9%. Conclusion: This study demonstrated that the degree of contrast enhancement of the lesions in CESM may be used in daily practice with easily performing a visual scale in predicting the malignancy potential of the lesions. [ABSTRACT FROM AUTHOR]

Aim: To study the outcome of simultaneous angioembolization and nephron sparing surgery in large renal angiomyolipomas. Materials and methods: A prospective study of carried out from 2016 to 2019. A total of 15 patients were included in the study with a lesion (angiomyolipoma) more than 10 cm in size, suitable for nephron sparing surgery. The workup of the patients included history, baseline blood investigations, ultrasonography, and CT urography including angiographic films. All the patients were taken up for selective of angioembolization of the feeding vessels of the AML carried out by the interventional radiologist followed by nephron sparing surgery in the same sitting. The short term outcomes studied were warm ischemia time, average blood loss, and length of post-operative hospital stay. The oncological outcome was evaluated by noting the surgical margins of histopathological specimen and functional outcome by assessing the function of the preserved renal parenchyma. Results: Twelve out of fifteen cases were female. The mean age was 42.25 years. All the patients had lesion more than 10 cm with seven tumors located at the lower pole, four at mid-pole, and four at upper pole. Eight patients had low complexity score on RENAL score (i.e. 4–6), five patients medium complexity score (i.e. 7–9), and two had high complexity score (i.e. ⩾10). Average blood loss was 200 ml, warm ischemia time was 18.46 min and postoperative stay was 3.55 days. All the 15 specimens sent for histopathology were confirmed as AML (angiomyolipomas) with margins free of tumor. Follow up CECT done at 4 months postoperatively revealed functioning residual renal parenchyma with prompt excretion of contrast. Conclusion: Large AML's are also amenable to nephron sparing surgery. However patient should always be warned about the possibility of total nephrectomy. Selective angioembolization helps in reducing the blood supply and risk of torrential bleeding thus facilitates in the removal of the tumor and increasing the chances of nephron sparing surgery. [ABSTRACT FROM AUTHOR]

We present the case of a 70-year-old female who was incidentally found to have a right angiomyolipoma extending into the renal vein, terminating 1 cm from the inferior vena cava. Due to the invasive nature of the angiomyolipoma in this case, surgical removal via a right laparoscopic nephrectomy was performed. This revealed an un-encapsulated but well-circumscribed fatty mass in the superior pole invading into the inferior vena cava, histologically consistent with a classic angiomyolipoma. Traditionally, patients with tumours extending into the inferior vena cava have been managed with an open surgical approach. Tumours with renal vein thrombus can be managed via an open or laparoscopic approach depending on the extent of vein invasion and local expertise. This is only the third reported case of angiomyolipoma with vascular invasion being treated laparoscopically. Despite the shorter length of the renal vein on the right side, this case demonstrates that a laparoscopic nephrectomy for the management of angiomyolipoma with renal vein thrombus is a feasible approach and would allow the patient faster recovery. Level of evidence: Not applicable. [ABSTRACT FROM AUTHOR]

Indocyanine green fluorescence imaging (ICG-FI)—a sensitive tool for detecting tumor localization in laparoscopic surgery—produces false positive results for benign liver tumors. This report is the first case of hepatic angiomyolipoma (HAML) treated laparoscopically with ICG-FI. We present the case of a 31-year-old woman with a liver tumor that was a 13-mm mass in the anterior superior segment. Though a benign tumor was suspected, malignant potential could not be ruled out. Therefore, minimally invasive laparoscopic resection using ICG-FI was planned. ICG, intravenously injected preoperatively, revealed the tumor's existence. Pure laparoscopic hepatectomy with ICG-FI was performed for excisional biopsy, during which the tumor was resected with adequate surgical margins, followed by histological confirmation of HAML. In conclusion, it is suggested that laparoscopic resection with ICG-FI is an effective minimal invasive surgery for tumors that are difficult to detect, such as HAML, leading to a safe surgical margin. [ABSTRACT FROM AUTHOR]

Sclerosing angiomyolipoma (sAML) is a rare variant of the perivascular epithelioid tumors exhibiting distinct morphology with extensive stromal hyalinization, which makes it challenging to recognize. It often lacks an adipose tissue component and melanocytic markers may be expressed only focally, further posing a diagnostic challenge. Here, we report a case of sAML of the left pararenal retroperitoneum in a 52-year-old woman with 92 months of clinical follow up and discuss the histologic features, immunoprofile, molecular alterations, and differential diagnoses that can aid in the diagnosis of this unique and rare entity. [ABSTRACT FROM AUTHOR]

Pulmonary lymphangioleiomyomatosis (LAM), a rare, progressive disease predominantly affecting the lungs of women of reproductive age, is often associated with renal angiomyolipoma (AML). We report the case of a 29-year-old female patient who presented to our obstetrics department at 37 weeks' gestation, complaining of abdominal pain, and constipation. Ultrasound noted a viable singleton with a large left-sided abdominal mass. After undergoing a caesarean section, she was referred to our urology department to assess her flank mass further. Computed tomography demonstrated a large, exophytic left renal mass measuring 22 cm x 16 cm x 13 cm, suggestive of an AML and numerous bilateral pulmonary cysts. A diagnosis of LAM and associated unilateral giant renal AML was made. As soon as she had fully recovered from her caesarean section, we removed the huge AML via a standard left-sided open nephrectomy without incident. We report this rare case of giant AML associated with LAM and review the literature about the association of these two conditions. [ABSTRACT FROM AUTHOR]

Background: Renal angiomyolipoma (AML) are benign masses that require detection of macroscopic fat for accurate diagnosis. Purpose: To evaluate fat material-specific images derived from dual-energy computed tomography (DECT) to diagnose renal AML. Material and Methods: This retrospective case-control study evaluated 25 renal AML and 44 solid renal masses (41 renal cell carcinomas, three other tumors) imaged with rapid-kVp-switch DECT (120 kVp non-contrast-enhanced [NECT], 70-keV corticomedullary [CM], and 120-kVp nephrographic [NG]-phase CECT) during 2017–2018. A radiologist measured attenuation (Hounsfield Units [HU]) on NECT, CM-CECT, NG-CECT, and fat concentration (mg/mL) using fat-water base-pair images. Results: At NECT, 100% (44/44) non-AML and 4.0% (1/25) AML measured >–15 HU. At CM-CECT and NG-CECT, 24.0% (6/25) and 20.0% (5/25) AML measured >–15 HU (size 6–20 mm). To diagnose AML, area under receiver operating characteristic curve (AUC) using –15 HU was: 0.98 (95% confidence interval [CI] 0.98–1.00) NECT, 0.88 (95% CI 0.79–0.91) CM-CECT, and 0.90 (95% CI 0.82–0.98) NG-CECT. At DECT, fat concentration was higher in AML (163.7 ± 333.9 [–553.0 to 723.5] vs. –2858.1 ± 460.3 [–2421.2 to –206.0] mg/mL, P <0.001). AUC to diagnose AML using ≥–206.0 mg/mL threshold was 0.98 (95% CI 0.95–1.0) with sensitivity/specificity of 92.0%/96.7%. Of AML, 8.0% (2/25) were incorrectly classified; one of these was fat-poor. AUC was higher for fat concentration compared to HU measurements on CM-CECT and NG-CECT (P =0.009–0.050) and similar to NECT (P =0.98). Conclusion: DECT material-specific fat images can help confirm the presence of macroscopic fat in renal AML which may be useful to establish a diagnosis if unenhanced CT is unavailable. [ABSTRACT FROM AUTHOR]

Tuberous sclerosis complex (TSC) is a rare multisystem neurocutaneous disorder associated with the growth of benign tumors in different organs such as the brain, lungs, kidneys, heart, and eyes. The dermatological findings of this disorder are very common, present at early age and not easy to miss. The neurological manifestations of TSC include seizures, autism, and intellectual disabilities. Furthermore, intracranial abnormalities and hamartoma formation in the heart and other organs are found among sufferers. The clinical diagnostic criteria have been critically evaluated and updated in the 2012 International Tuberous Sclerosis Conference. The diagnosis is based on genetic criteria, clinical criteria, and various manifestations of skin, kidneys, lungs, and brain. The management involves multispecialty and multidisciplinary approaches. Here, we present a case of a 13-year-old female with characteristic clinical, radiological, and pathological features of TSC. [ABSTRACT FROM AUTHOR]

Myopericytoma, a perivascular myoid neoplasm, is commonly found in the dermis or subcutaneous tissues; however, its occurrence in visceral organs is unusual. Here, we present an extremely rare tumor of intravascular myopericytoma of the right renal vein. A 44-year-old man was incidentally diagnosed with a mass in the right kidney during a routine checkup. A nephrectomy was performed because the urologist suspected renal cancer. A gross examination of the resected specimen revealed a well-circumscribed brown mass in the renal hilum. Histologically, the tumor showed a concentric multilayered proliferation of spindle cells surrounding blood vessels. Immunohistochemical staining showed that the spindle-shaped tumor cells were negative for desmin but positive for α-smooth muscle actin and h-caldesmon, indicating their myoid nature. We confirmed that the tumor was located in the right renal vein because it was encased within a thick wall that was desmin-positive and contained elastic fibers, as shown by Elastica van Gieson staining. The patient was diagnosed with an intravascular myopericytoma of the right renal vein. There are several differential diagnoses for renal mesenchymal tumors, including angiomyolipoma. This emphasizes the importance of considering these uncommon tumors when examining nephrectomy specimens. [ABSTRACT FROM AUTHOR]

Background: Surveillance of sporadic renal angiomyolipomas is a growing issue for physicians and radiologists. Current treatment recommendations favor active surveillance. However, the evidence underlying these is based on small case series, which also typically include angiomyolipomas associated with tuberous sclerosis. Purpose: To evaluate the natural growth pattern of sporadic renal angiomyolipomas in patients without tuberous sclerosis. Material and Methods: A retrospective review was performed in three separate tertiary referral centers. A keyword search of each institutions PACS history was performed. Inclusion criteria were angiomyolipomas > 1 cm in size, three years of follow-up, and lesions requiring treatment before reaching three years of follow-up. Exclusion criteria included a diagnosis of tuberous sclerosis, pregnancy, prior treatment with embolization without any prior imaging, and lesions which were treated on presentation. Growth of the angiomyolipomas was evaluated on the basis of maximum dimension on initial and follow-up images. Results: Sixty-three patients were identified in total, with 64 lesions eligible for inclusion. The majority of patients were women (55/63). The mean age at which the angiomyolipomas discovered was 56.4 years. Mean total growth was 0.085 mm and mean follow-up was 65.5 months. At initial measurement, the mean maximum dimension of the lesions in our cohort was 2.08 cm. After follow-up, this was 2.16 cm. The average rate of growth was 0.015 cm per year. Conclusion: Sporadic angiomyolipomas exhibit minimal, if any, natural growth. Current surveillance strategies could be relaxed. [ABSTRACT FROM AUTHOR]

Background: Partial nephrectomy may be complicated by postoperative hemorrhage, which may be treated by transcatheter embolization. Purpose: To assess the safety and efficacy of embolotherapy for hemorrhagic complications of partial nephrectomy and to analyze the potential correlation between multiple bleeding sites on angiography and surgical complexity Material and Methods: A cohort of 25 patients presenting with severe, postoperative bleeding after partial nephrectomy and treated with catheter-directed superselective embolization was included. Patients' demographics, radiological investigations before the embolization, and clinical outcome after embolization were analyzed. Mann–Whitney U test was used to analyze the potential difference in the RENAL score between patients with one or more bleeding sites in the resection area. Results: Selective renal angiography revealed multiple bleeding sites at the resection bed in 8 (32%) patients with amorphous contrast extravasation in 10 (40%) patients. Embolization with use of a microcatheter and microcoils was effective to stop the bleeding in all but one patient, the latter requiring a second embolization two days later. Transient decrease in renal function was noted in 3/25 (12%) patients with full recovery in two of the three. Patients with multiple bleeding sites did not show significantly different RENAL scores compared to patients with a single bleeding site (P = 0.148). Conclusion: Embolotherapy for postoperative partial nephrectomy-related bleeding is safe and effective with a low rate of recurrent bleeding. The number of bleeding sites at the resection area did not correlate to the RENAL score. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the safety and efficacy of the microvascular plug (MVP) for selective renal artery embolization. Methods: Retrospective review was performed on a cohort of 6 patients undergoing renal artery embolization using the MVP between July 2015 and August 2018. Patients' demographics, indication for embolization, technical details of the embolization procedure, and clinical events were gathered from the patients' electronic medical records. Results: The patients underwent selective renal artery embolization with a MVP for iatrogenic vascular injuries (n = 3), traumatic vascular injuries (n = 2), and for elective embolization of an angiomyolipoma (n = 1), in native kidneys (n = 4) or in renal allografts (n = 2). Immediate occlusion of the feeding artery was achieved with 1 MVP device in 4 patients. In 1 patient, a second MVP was needed, and in another patient, additional 0.018-inch microcoils were used to completely occlude the injured artery. Technical success was achieved in all patients. The volume of the resulting renal infarction was estimated less than 5% of the renal volume. No other procedure-related complications occurred. Conclusion: The MVP is a safe and effective device allowing superselective renal artery embolization. Therefore, we recommend the MVP as a valuable embolic in superselective renal artery embolization. Additionally, a single device is sufficient in most cases, potentially reducing the cost, duration, and radiation exposure of the procedure. [ABSTRACT FROM AUTHOR]

Angiomyolipomas are rare benign tumors of the kidneys, with a risk of spontaneous hemorrhage including severe retroperitoneal bleedings. In this study, we report clinical outcomes of 5 patients who underwent 8 embolization sessions using 96% ethanol, as there is scarce data using this embolic agent for this indication. The primary angiographic success could be achieved in all but 1 lesion, which was not accessible due to vasospasm of the supplying vessel. Therapeutic success could be demonstrated in all treated cases for which follow-up imaging was available (n = 3). In 1 complex patient, a mildly reduced renal function, as well as a new onset of arterial hypertension was detected after treatment. Nontarget embolization of vital kidney tissue was demonstrated in another patient; it remained asymptomatic. Embolization therapy using 96% ethanol is an optional method to treat renal angiomyolipomas. [ABSTRACT FROM AUTHOR]

Background: Morphological findings showed poor accuracy in differentiating angiomyolipoma without visible fat (AMLwvf) from renal cell carcinoma (RCC). Purpose: To determine the performance of a machine learning classifier in differentiating AMLwvf from different subtypes of RCC based on whole-tumor slices of CT images. Material and Methods: In this retrospective study, 171 pathologically proven renal masses were collected from a single institution. Texture features were extracted from whole-tumor images in three phases including the pre-contrast (PCP), corticomedullary (CMP), and nephrographic (NP) phases. A support vector machine with the recursive feature elimination method based on fivefold cross-validation (SVM-RFECV) with the synthetic minority oversampling technique (SMOTE) was utilized to establish classifiers for differentiating AMLwvf from all subtypes of RCC (all-RCC), clear cell RCC (ccRCC), and non-ccRCC. The performances of the classifiers based on three-phase and single-phase images were compared with each other and morphological interpretations. Results: A machine learning classifier achieved the best performance in differentiating AMLwvf from all-RCC, ccRCC, and non-ccRCC. The performance of the best machine learning classifier for differentiating AMLwvf from all-RCC (area under the curve [AUC] = 0.96) and ccRCC (AUC = 0.97) was higher than that for differentiating AMLwvf from non-ccRCC (AUC = 0.89); morphological interpretations achieved lower performance for differentiating AMLwvf from all-RCC (AUC = 0.67), ccRCC (AUC = 0.68), and non-ccRCC (AUC = 0.64). Conclusion: Machine learning can be a useful non-invasive technique for differentiating AMLwvf from all-RCC, ccRCC, and non-ccRCC, and it can be more accurate than morphological interpretation by radiologists. [ABSTRACT FROM AUTHOR]

Eosinophilic solid and cystic renal cell carcinoma (ESCRCC) is a recently described distinct renal neoplasm known to occur almost exclusively in female patients with or without tuberous sclerosis complex (TSC). We report a case of ESCRCC with 2 synchronous angiomyolipomas, including 1 angiomyolipoma with epithelial cysts (AMLEC), a rare cystic variant of AML that typically arises sporadically in the absence of TSC, in a 46-year-old woman with TSC. Besides additional copy number alterations identified in ESCRCC via molecular karyotyping, we also report a unique histologic feature of TSC-associated ESCRCC previously not described in detail, with formation of semicircular multinucleated neoplastic giant cells engulfing an additional intact neoplastic cell, simulating emperipolesis. To the best of our knowledge, this is the first reported case of ESCRCC with concurrent AMLEC in a patient with TSC, confirmed through additional genetic testing showing a germline heterozygous mutation in TSC1. Awareness of ESCRCC helps avoid the pitfall of a diagnosis of unclassified renal cell carcinoma, a typically much more aggressive tumor. [ABSTRACT FROM AUTHOR]

Abstract Renal angiomyolipomas (AMLs) are benign tumours that may occur sporadically in the general population or in patients with tuberous sclerosis complex. The concern with AMLs is that of retroperitoneal hemorrhage, which can be fatal. Classically the trigger for prophylactic intervention was thought to be an AML diameter of ≥4 cm. However, this value is largely based on data from case series and heterogeneous retrospective studies. The PICO (patient, intervention, comparison, outcome) paradigm was used to systematically search the Cochrane database, TRIP database, and PubMed. The quality of evidence in the literature is poor regarding the indications for prophylactic embolization of AMLs (level 4). There are no prospective studies that adequately assess embolization vs other treatment modalities. However, using the available evidence we have produced recommendations for when intervention should be considered. We have also made recommendations regarding the direction of future research. Résumé Les angiomyolipomes sont des tumeurs bénignes du rein qui peuvent se manifester de façon sporadique au sein de la population ou chez des patients atteints de sclérose tubéreuse de Bourneville. Les angiomyolipomes posent un risque d'hémorragie rétropéritonéale pouvant être mortelle. L'intervention prophylactique était depuis longtemps fondée sur un diamètre de l'angiomyolipome supérieur ou égal à 4 cm. Cette valeur repose cependant en grande partie sur des données issues de séries de cas et d’études rétrospectives hétérogènes. Le paradigme PICO (patient, intervention, comparaison, résultat) a été utilisé pour effectuer une recherche systématique dans les bases de données Cochrane, TRIP et PubMed. La documentation scientifique contient peu de données probantes de qualité en ce qui a trait aux indicateurs de l'embolisation prophylactique des angiomyolipomes (niveau 4). Il n'existe pas non plus d’études prospectives qui évaluent adéquatement l'embolisation par rapport à d'autres modalités de traitement. Nous avons cependant pu formuler des recommandations à partir des données probantes disponibles pour déterminer à quel moment une intervention doit être envisagée. Nous avons également fait des recommandations en vue d'orienter de futurs travaux de recherche. [ABSTRACT FROM AUTHOR]

Background Recent literature suggests that intratumoral hemorrhage detection may be helpful in differentiating papillary renal cell carcinoma (pRCC) from fat-poor angiomyolipoma (fpAML). Purpose To determine whether intratumoral hemorrhage detected using chemical shift magnetic resonance imaging (MRI) and T2*-weighted (T2*W) gradient echo (GRE) can be used to differentiate pRCC from fpAML. Material and Methods This retrospective study included 42 patients with pRCC (n = 28) and fpAML (n = 14) who underwent MRI followed by surgery. Two blinded radiologists independently assessed the presence of intratumoral hemorrhage using chemical shift MRI (decrease in signal intensity from opposed- to in-phase) and T2*W GRE ("blooming"). Consensus reading was determined for discrepant cases. MRI findings were compared using Chi-square test. Inter-observer agreement was assessed using kappa statistics. Results Inter-observer agreement was substantial for both sequences ( k = 0.622 and 0.793, P < 0.001). For chemical shift MRI, the prevalence of intratumoral hemorrhage was significantly greater in pRCC than in fpAML (71.4% versus 28.6%, P = 0.019 for reader 1; 64.3% versus 14.3%, P = 0.003 for reader 2; and 75% versus 21.4%, P = 0.002 for the consensus). T2*W GRE showed a similar tendency (46.4% versus 14.3%, P = 0.049 for both readers; and 50% versus 14.3%, P = 0.042 for the consensus). Using the consensus reading, sensitivity and specificity of determining pRCC were 75% and 78.6% for chemical shift MRI and 50% and 85.7% for T2*W GRE. Conclusion The prevalence of intratumoral hemorrhage identified from chemical shift MRI or T2*W GRE was significantly different between pRCC and fpAML. These hemorrhage-sensitive MRI sequences may be used as an adjunctive tool for discriminating between the two entities. [ABSTRACT FROM AUTHOR]

Renal angiomyolipoma (AML) is a benign neoplasm of the kidney arising sporadically in an idiopathic manner, or syndromically as a component of tuberous sclerosis complex. Although the classic AML has no malignant potential, and is the most common mesenchymal tumor of the kidney, variant AML cases with epithelioid morphology have demonstrated aggressive or invasive behavior. Classic AML, on the other hand, can occasionally display focal histology concerning for sarcomatous transformation, but in the absence of invasive features, it is easy to distinguish from a malignancy. In this article, we describe a remarkable case of classic AML that harbored areas histologically mimicking liposarcoma and invaded into the renal vein and extended up to inferior vena cava, thereby presenting a unique diagnostic conundrum. However, the tumor is negative for a CPM gene amplification, arguing against a liposarcomatous transformation. In addition, the patient does not have any sign of recurrence and metastasis clinically after 2 years of follow-up, also favoring a benign diagnosis of this tumor. [ABSTRACT FROM AUTHOR]

Background The rich neovascularization of renal angiomyolipoma (AML) has a tendency for spontaneous rupture with subsequent hemorrhage. Nephrectomy or nephron-sparing surgery has rarely been used as a primary treatment in urgent situations. Purpose To evaluate the safety and long-term outcomes for patients treated by urgent transcatheter arterial embolization (TAE) for spontaneous ruptured renal AML with severe hemorrhage. Material and Methods A retrospective evaluation was performed of 25 renal AML cases with spontaneous hemorrhage confirmed by imaging. Polyvinyl alcohol (PVA) particles and coils of multiple sizes were used to embolize the spontaneous renal AML ruptures. Results The technical success rate of TAE was 96% (24/25). One week post-TAE, 1 patient with recurrent hemorrhage underwent emergency nephrectomy. Minor complications affected 16 patients with post-embolization syndrome; 15 patients resolved using conservative measures and one patient received nephrectomy post TAE 1 week later. All patients were followed up for 24-72 months (median, 50.2 months). Surgical treatment was avoided for 92% (23/25) of patients, and the re-embolization rate was 0% at 2 years post TAE. In the 23 patients without surgical treatment, the mean maximum diameter of renal AML was reduced from 12.4 ± 5.5 cm to 6.3 ± 2.5 cm and no hemorrhage occurred during follow-up. Conclusion Urgent TAE is a technically feasible and minimally invasive procedure for controlling severe hemorrhage and preservation of renal function following spontaneous ruptured renal AML. [ABSTRACT FROM AUTHOR]

Background: Angiomyolipoma (AML) with minimal fat may mimic renal cell carcinoma (RCC) and is difficult to distinguish from RCC with imaging studies alone. Precise diagnostic strategies have been explored to discern AML with minimal fat from RCC. Purpose: To compare the morphological and enhancement features of AML with minimal fat with those of size-matched RCC on computed tomography (CT). Material and Methods: Our study included 143 pathologically proved renal tumors (29 AML with minimal fat: mean diameter, 2.5 cm; range, 1.2-4 cm; 114 RCC: mean diameter, 2.8 cm; range, 1.3-4 cm). All patients underwent biphasic helical CTs. Two radiologists retrospectively evaluated the morphological (i.e. non-round and round appearances, with or without capsule) and enhancement features (i.e., wash-out, gradual, or prolonged). For the parameters that had statistically significance between the two groups, we calculated the positive and negative predictive values by using the univariate χ(2) test. P < 0.05 indicated a significant difference. Results: AML with minimal fat showed a non-round appearance without a capsule (n = 24, 83%) and prolonged enhancement (n = 20, 69%). The positive and negative predictive values of the non-round appearance without capsule for differentiating AML with minimal fat from RCC were 82.8% and 95.6%, respectively. The positive and negative predictive values of prolonged enhancement were 62.5% and 90.8%, respectively. These features were valuable predictors for AML with minimal fat from RCC. Conclusion: CT images with non-round shape without capsule and prolonged enhancements may be used to differentiate AML with minimal fat from RCC. [ABSTRACT FROM AUTHOR]

Renal angiomyolipomata associated with tuberous sclerosis complex are often bilateral, multiple and progressive. They cause significant morbidity and mortality in older children and adults. Surveillance and pre-emptive treatment reduce this risk. Recent research suggests treatment with mammalian target of rapamycin inhibitors is better at preventing bleeding, recurrence, and preserving renal function than percutaneous embolization. [ABSTRACT FROM AUTHOR]

Angiomyolipoma is a mesenchymal neoplasm characterized by the coexpression of melanocytic and smooth muscle markers. Sarcoidosis is a multisystem disorder of unknown etiology, which presents with characteristic nonnecrotizing granulomas and rarely involves the kidney. The coexistence of renal sarcoidosis with renal neoplasms is exceedingly rare and was reported only with renal cell carcinoma. Renal sarcoidosis associated with a nonepithelial renal neoplasm, such as an angiomyolipoma has never been reported. We present the first reported case of sarcoid granulomas in a renal angiomyolipoma, including morphologic and immunohistochemical features. [ABSTRACT FROM AUTHOR]

Background: Exophytic renal angiomyolipoma and liposarcoma are two representative tumors in the retroperitoneum with fatty components that have potential to be misdiagnosed with each other.Purpose: To compare the computed tomography (CT) findings of exophytic renal angiomyolipoma and perirenal liposarcoma.Material and Methods: Fourteen and 16 cases with histologically-proven exophytic renal angiomyolipoma and perirenal liposarcoma, respectively, with preoperative CT from January 2000 to December 2013 were reviewed by two radiologists blinded to the clinical and pathological findings for an array of CT findings. These findings were compared between exophytic renal angiomyolipoma and perirenal liposarcoma using the Student t-test and Fisher's exact test.Results: Patients with exophytic renal angiomyolipoma were younger (P = 0.001) without differences in sex (P = 1.000). Exophytic renal angiomyolipomas were smaller (P = 0.004) and more commonly showed the following findings: renal parenchymal defect (P < 0.001), multiple linear vessels (P = 0.026), aneurysmal dilatation of intratumoral vessels (P = 0.024), renal parenchymal vascular pedicle (P < 0.001), hemorrhage (P = 0.037), encapsulated margin (P = 0.001), and other intrarenal fatty lesions (P = 0.037). No significant difference was seen in laterality, renal hilar vascular pedicle, non-fatty soft tissue nodule, calcification, or kidney displacement (P = 0.236-1.000).Conclusion: Several CT findings were significantly different between exophytic renal angiomyolipoma and perirenal liposarcoma and may be helpful for differentiating between the two entities when confronting a fatty mass in the perirenal space. [ABSTRACT FROM AUTHOR]

The article presents case studies of a 63-year-old female and a 67-year-old female with hepatic perivascular epithelioid neoplasms (PEComas). The first case was found to have a liver mass, positive for desmin, and a malignant perivascular epithelioid cell tumor and undergone a right hepatectomy. The second case was found to have hepatic PEComa consistent with angiomyolipoma and was treated by resection.

Synchronous renal cell neoplasms (RCNs) and angiomyolipomas (AML) occurring in the same kidney are rare. The aim of this retrospective study is to investigate the incidence and clinicopathological features of concurrent AML and RCN in patients without tuberous sclerosis complex (TSC). Partial and radical nephrectomy specimens with a diagnosis of RCN and AML from 1995 to May 2013 were reviewed. Cases were assessed for histological subtype of AML and RCN, topographic relationship between the AML and the RCN, and clinical characteristics. A total of 565 RCNs and 19 AMLs were identified. Of 19 cases of AML, 9 (47%) were associated with renal tumors. Clear-cell renal cell carcinoma (RCC) was the most common malignancy associated with AML (56%). The mean age of patients with concomitant AML and RCN was higher than the mean age of patients with only AML (58.6 vs 55.5 years). The majority of patients with concomitant AML and RCN were female (78%). All concurrent sporadic AMLs were benign. We identified one case of bilateral clear-cell RCC with concomitant multiple bilateral AMLs in a patient with TSC. [ABSTRACT FROM AUTHOR]

Tumor-to-tumor metastasis is a very rare phenomenon. The most common donor and recipient of tumor-to-tumor metastasis are carcinomas of lung and renal cell carcinoma, respectively. We report a case of primary lung adenocarcinoma that metastasized into a renal angiomyolipoma 9 years after the resection of primary lung tumor. Comparisons in morphology, immunohistochemical profiles, and genetic mutations indicate that the tumor metastasizing into angiomyolipoma originated from the same clone of previous lung adenocarcinoma. Albeit rare, pathologists should be aware of the possibility of tumor-to-tumor metastasis when confronting a neoplasm exhibiting 2 distinct morphological features. [ABSTRACT FROM PUBLISHER]

The biological character of epithelioid angiomyolipoma (EAML) remains controversial and little is known about EAML in children. We present a case of a 7-year-old boy with abdominal distention, diagnosed as EAML. Under microscopy, epithelioid cells were observed, with eosinophilic or slightly eosinophilic cytoplasm and nuclear pleomorphism, thick-walled blood vessels, and some cells that were differentiated to smooth muscle cells or fat cells were easily observed. Immunochemical staining showed that Melan-A and HMB45 were positive. The tumor presented highly aggressive biobehavior. Furthermore, we reviewed and analyzed cases of diagnosed EAML in our hospital and those reported in the literature. Renal EAML (10/17) was most common, and the EAML of 3 of 17 patients metastasized to other organs. [ABSTRACT FROM AUTHOR]

Background: Neoplasms showing perivascular epithelioid cell differentiation (PEComas) are uncommon tumors of the sinonasal tract. They are often misdiagnosed as angiomyolipoma or a simple benign tumor or polyp. We present a further case of a sinonasal PEComa and review the literature in an attempt to ascertain their malignant potential. Methods: Published evidence on invasiveness and characteristics were defined on systematic review. MEDLINE and EMBASE were searched from 1966 and 1980, respectively, to week 3 of December 2010. Publications reporting PEComa or angiomyolipoma were sought. Only those describing a sinonasal origin were included. Demographics, anatomic site, local invasion, recurrence rates, and mortality were recorded. A case report of a locally invasive intranasal PEComa is described. Results: In addition to the case we present, 12 case reports were located (n = 13). The mean age of patients was 59.6 (SD, 14.98 years) years. The location was within the right sinonasal tract in 54% of cases, the left sinonasal tract in 38% of cases, and not reported in 8% of cases. Treatment focused on local surgical excision and this was achieved endoscopically in 100% of cases. Recurrence rate was 8%. Mean follow-up was 17.4 (SD, 20.68 months) months. Invasion was noted in 23% of cases. There was a single death recorded. Conclusion: PEComas of the paranasal sinuses and skull base appear to have a biological behavior different from simple benign angiomyolipomas reported elsewhere in the body. PEComa may be more intermediate or malignant in clinical behavior. [ABSTRACT FROM AUTHOR]

Renal epithelioid angiomyolipoma (EAML) is a rare but distinct variant of angiomyolipoma, closely simulating renal cell carcinoma or sarcoma both clinically and histopathologically. This report presents an unusual case of unilateral simultaneous renal EAML and renal clear cell carcinoma. A 52-year-old man without any sign of tuberous sclerosis had a complaint of 6-month history of pain in left renal area and had macroscopic hematuria twice within the recent 1 month. Computed tomography showed the presence of 2 masses in the upper and lower portion of the left kidney. The patient underwent left radical nephrectomy. Histological examination revealed the upper mass was composed of medium to large epithelioid cells with clear or eosinophilic cytoplasm and numerous giant multinucleated cells. Adult-appearing adipose tissue and coagulative necrosis could also be observed focally in the mass. Immunohistochemically, the tumor cells in the upper mass showed positive reactions to actin, HMB-45, Melan-A, and CD68 but negative reactions to pan-cytokeratin (pan-CK), epithelial membrane antigen, and CD10. However, the lower mass was composed of diffusely monomorphic clear cells with strongly immunoreactive for pan-CK, vimentin, and CD10, whereas without expression for HMB-45 and actin. The patient showed no evidence of recurrence or metastasis during 1-year postoperative following-up period. To the authors’ knowledge, this is the first report of coincidental renal EAML and clear cell carcinoma in the same kidney. Unlike classic triphasic angiomyolipoma, adjuvant therapy after resection should be considered for renal EAML because of its malignant potential, more aggressive behavior and poor prognosis. [ABSTRACT FROM PUBLISHER]

Renal angiomyolipoma (AML) is a benign neoplasm with a propensity to bleed among patients with tumors exceeding 4 cm in diameter but can be effectively treated with transarterial embolization to arrest or prevent hemorrhage. We report the use of transradial approach to embolize a bleeding AML in a pregnant patient in order to minimize pelvic radiation. This case illustrates the utility of transradial access as an access approach for performing superselective visceral embolization when a femoral approach is undesirable or not possible. [ABSTRACT FROM PUBLISHER]

Percutaneous renal surgery provides a minimally invasive approach to the kidney for stone extraction in a number of different clinical scenarios. Certain clinical cases present inherent challenges to percutaneous access to the kidney. Herein, we present scenarios in which obtaining and/or maintaining percutaneous access is difficult along with techniques to overcome the challenges commonly encountered. Also, complications associated with these challenging percutaneous renal surgeries are discussed. [ABSTRACT FROM PUBLISHER]

The DNA-binding factor TFE3 is closely related to microphthalmia-associated transcription factor (MiTF) and is over-expressed in alveolar soft part sarcoma (ASPS) and select renal cell carcinomas. Reports of TFE3 expression in PEComa prompted investigation into TFE3 expression among other members of the putative MiTF group of neoplasms. The authors examined cases of PEComa (n = 6), conventional angiomyolipoma (AML; n = 22), metastatic melanoma (n = 16), and clear cell sarcoma (CCS; n = 9) for TFE3 expression. Nuclear immunostaining was observed in 74% (39/53) of cases, as follows: 5/6 PEComas, 18/22 AMLs, 10/16 metastatic melanomas, and 6/9 CCSs. However, with the exception of PEComas, compared with ASPS controls, TFE3 staining was significantly less intense in the tumors examined. These results illustrate that TFE3 immunoreactivity is detectable in other members of the MiTF family of neoplasms. For this reason, such neoplasms warrant consideration in the differential diagnosis with nuclear TFE3 immunoreactivity, particularly when staining is focal and less intense. [ABSTRACT FROM PUBLISHER]

Tuberous sclerosis complex results from mutations in 1 of 2 interacting gene products, hamartin or tuberin. The syndrome is characterized by hamartomas and neoplastic lesions, including angiomyolipomas of the kidney and other organs. Renal cell carcinoma (RCC) in tuberous sclerosis remains relatively poorly characterized because historical studies were confounded by the inclusion of epithelioid angiomyolipomas. The authors present a patient with tuberous sclerosis and bilateral renal lesions, including multiple minute angiomyolipomas, cortical cysts, and 4 separate RCCs of unclassified type. The carcinomas shared distinctive morphological features, including sheet-like, glandular, trabecular, or cystic architecture and abundant granular eosinophilic cytoplasm. By definition, the carcinomas were keratin positive and negative for HMB-45 and Melan-A. Detailed immunohistochemical analysis revealed heterogeneity among the cortical cysts and carcinomas. The histopathological features of these carcinomas illustrate characteristics of renal carcinoma that are probably related to genetic alterations of tuberous sclerosis. [ABSTRACT FROM PUBLISHER]

Although different diseases, tuberous sclerosis complex and autosomal dominant polycystic kidney disease have been seen in association, the molecular basis of this being the proximity of tuberous sclerosis complex 2 and polycystic kidney disease 1 genes on the same chromosome (16p 13.3). Therefore, the classic autosomal dominant polycystic kidney disease renal phenotype may occur in the context of tuberous sclerosis complex disease as a result of large deletions involving both the polycystic kidney disease 1 and tuberous sclerosis complex 2 genes. This is known as the tuberous sclerosis complex 2/autosomal dominant polycystic kidney disease 1 contiguous gene syndrome. The criteria for this condition are fulfilled when renal lesions typical for classic autosomal dominant polycystic kidney disease phenotype are associated with tuberous sclerosis complex phenotype. We present a new case of the sporadic form of this genetic disorder. The diagnosis of tuberous sclerosis complex in this patient was established on the presence of major and minor features, and the diagnosis of ADPKD was based on the presence of numerous large roundish renal cysts lined by a nondescript tubular epithelium. Sporadic cases of autosomal dominant polycystic kidney disease and tuberous sclerosis complex do occur. Molecular analysis was not performed because the patient's parents refused permission. [ABSTRACT FROM AUTHOR]

The article presents a case of a 40-year old woman with tuberous sclerosis disease. The patient was transferred from another hospital with left flank pain and gross hematuria. Her medical examination revealed a mass in the left flank with associated tenderness. Moreover, the patient was referred to radiology for an ultrasound (US) of the abdomen and a computed tomography (CT) scan of the abdomen and pelvis.

A unique case of a mixed epithelial stromal tumor (MEST) that was predominantly composed of adipose tissue is reported here. Radiographically and grossly, the lesion was thought to be an angiomyolipoma, based upon its fatty appearance. Microscopically, the lesion was predominantly composed of mature adipose tissue but also contained clusters of bland tubules surrounded by smooth muscle bundles and collagen. By immuno-histochemistry, the stroma labeled diffusely for estrogen and progesterone receptors, while the muscle bundles labeled for desmin. Melanocytic markers HMB45 and Melan A, typically positive in angiomyolipoma, were nonreactive. This case expands the morphologic spectrum of MEST to include mimics of angiomyolipoma. [ABSTRACT FROM AUTHOR]

We report the case of a 30-year-old woman with persistent pain at the right hypochondrium, relapsing fever, and normal serum tests. Ultrasound showed a hyperechoic inhomogeneous mass; following sulfur hexafluoride injection, uniform enhancement at 14-16 s and rapid wash-out at 26 s was found. Multidetector computed tomography showed an inhomogeneously hypodense mass, with no detectable negative density values, characterized by inhomogeneous enhancement at the arterial phase and wash-out at the portal phase. Histopathology demonstrated a hepithelioid angiomyolipoma with a poor fatty component. This diagnosis should always be considered in the presence of a very rapid wash-out after intravenous contrast injection. However, a hepatocellular carcinoma cannot be excluded and the final diagnosis of low-fat angiomyolipoma must be pathologically proved based on immunohistochemistry. [ABSTRACT FROM AUTHOR]

Presents cases of pleomorphic angiomyolipomia (AML) composed of bizarre epithelioid smooth muscle cells located in the gastrointestinal tract. Case histories; Immunohistochemical results; Clinicopathologic features of AML of gastrointestinal tract; Differential diagnosis; Treatment.

HMB-45 monoclonal antibody is thought to be highly specific for melanocytic proliferations. In a recent study of two cases of hepatic and one case of renal angiomyolipoma, strong staining of lesional cells with this antibody was unexpectedly encountered. In follow-up evaluation, the authors studied 51 additional soft tissue, renal, and brain tumors and tumor-like processes, with emphasis on those with prominent vascular, myogenous, and fatty components or those known to be associated with tuberous sclerosis. Varying degrees of staining with HMB-45 were seen in 17 of the lesions tested. Strong staining with HMB-45 was demonstrated in four renal angiomyolipomas. Clearly positive results were also obtained in three other processes associated with the tuberous sclerosis complex, including two cardiac rhabdomyomas and one tuberous lesion of the brain. Weak staining of several other mesenchymal and neural lesions was also observed. Electron microscopic studies showed a spectrum of granules within angiomyolipoma, some of which resembled melanosomes and others renin granules. Similar granules were observed in cardiac rhabdomyoma, cerebral tuberous lesions, and in subependymal giant cell astrocytoma. We propose that tuberous sclerosis- associated tumors and tumor-like processes are interrelated, and that these and perhaps other mesenchymal proliferations may share components previously believed to be unique to melanocytic lesions. [ABSTRACT FROM AUTHOR]

Renal angiomyolipoma (AML) is a rare benign tumor that can extend into the renal vein, inferior vena cava and the right atrium. AML is a mesenchymal tumor composed of smooth muscle, fat and vascular elements. In rare instances, the tumor may release a fatty tissue to the pulmonary vasculature, which can lead to cardiopulmonary collapse and death. Only four cases of fat pulmonary embolism secondary to AML have been reported in the literature but our case was the first to present as asymptomatic. Our patient had left renal AML extending to the renal vein that was associated with fat pulmonary embolus. The patient underwent uncomplicated radical nephrectomy and was discharged home on no anticoagulation. Follow-up chest computed tomography showed no extension of the pulmonary embolism. Whether embolectomy or anticoagulation is necessary in asymptomatic pulmonary embolism secondary to renal AML is unclear. Although controversial, some surgeons prefer to place an inferior vena cava filter prior to radical nephrectomy to prevent dislodgement of new intraoperative emboli, which can lead to catastrophic outcome. [ABSTRACT FROM PUBLISHER]

Clear cell carcinoma is the most common histotype among renal cell tumors. The prominent vascular network of sinusoidal vessels lined by delicate endothelial cells may often lead to hemorrhagic areas with secondary deposition of chunky birefringent hemosiderin granules. The finding of pigmentation other than iron, and in particular melanin deposits, in renal tumors is a rare occurrence that should lead to differential diagnosis with other primary and metastatic tumors of the kidney. [ABSTRACT FROM AUTHOR]

The article presents a comparison of case studies of patients who were diagnosed with renal angiomyolipoma using CT scan. The series of cases of renal angiomyolipoma illustrates the importance of CT scanning in both preoperative diagnosis and subsequent management of this condition. Accurate preoperative assessment of the size of the lesion can influence the decision as to when best to operate on these tumors and whether partial or total nephrectomy is indicated.