Question

    Angiomyolipoma (Angiomyolipomas)

    Angiomyolipome der Niere CT[1]

    Angiomyolipoma is a benign neoplasm of mesenchymal origin that primarily consists of proliferating adipocytes, smooth muscle cells, vascular structures, and macrophages. It most frequently affects the kidneys and may be associated with tuberous sclerosis.

    Presentation

    Most AML patients are asymptomatic. Here, AMLs are generally incidental findings, observed on images obtained for non-related reasons. In the case of symptomatic AML, patients may present with lower back and flank pain radiating from the affected kidney(s). Accordingly, hepatic AML may provoke upper abdominal pain, sensations of early satiety and fullness. Tumors may be palpable and sensitive to pressure. Renal AML may interfere with kidney function and affected individuals may claim hematuria.

    Since about one in five AML patients suffers from TSC, symptoms related to this disease shall be briefly summarized here. Besides multiple mesenchymal tumors, mental retardation and epilepsy due to cortical dysplasia, as well as dermatological and dental anomalies, are typical of TSC. With regards to the former, numerous facial angiofibroma's distributed in a butterfly-like pattern are most characteristic of the disease, but patients may also present with ungual fibromas, retinal hamartoma, subependymal astrocytoma, rhabdomyoma, lymphangioleiomyomatosis and mesenchymal tumors of the kidneys and liver [14]. In this context, cysts are often observed in close proximity to multiple AML.

    While tumor size upon the initial presentation of AML patients varies, TSC-associated AML is typically larger than those deemed sporadic. According to a retrospective study conducted in Egypt, TSC-related AML usually measure more than 15 cm in diameter at the time of diagnosis, while sporadic AML have a mean size of only 4 cm [7]. Similarly, growth rates differ largely (1.25 and 0.19 cm per year in the case of TSC-associated AML and sporadic tumor growth, respectively). As has been indicated above, sporadic cases of renal AML usually manifest in form of unilateral disease.

    Vessels passing through AML are prone to aneurysm formation and rupture, and this particularly applies to larger tumors. Patients diagnosed with AML measuring more than 4 cm in diameter have a risk of more than 50% of spontaneous hemorrhages [15]. Such events may lead to anemia, but rupture of major vessels may also cause life-threatening blood loss. Affected patients may present with sudden-onset abdominal pain and hemorrhagic shock.

    Liver, Gall & Pancreas
    Hepatomegaly
    • Examination revealed hepatomegaly with tenderness in the right upper quadrant.[jmedicalcasereports.com]
    • On physical examination, there was a hepatomegaly, and the tumoral mass was palpable in the right flank and iliac region, extending to the mesogastrium and going beyond the midline; it had a smooth surface of solid consistence, of low mobility, and clear[scielo.br]
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  • Entire body system
    Anemia
    • Anemia- Loss of blood in urine may result in anemia .[epainassist.com]
    • A minority of patients present with hematuria, flank pain, or a palpable mass; presentation with unexplained anemia, as in this case, is decidedly unusual.[cancernetwork.com]
    • Laboratory Abnormalities: The most common laboratory abnormalities (incidence 50%) were hypercholesterolemia (85%), hypertriglyceridemia (52%), and anemia (61%).[hcp.novartis.com]
    • The most common laboratory abnormalities (  40%, any grade) in the everolimus group were hypercholesterolemia (85% vs 46% in placebo group), anemia (61% vs 49%), hypertriglyceridemia (52% vs 10%), and hypophosphatemia (49% vs 15%).[ascopost.com]
    • Such events may lead to anemia, but rupture of major vessels may also cause life-threatening blood loss.[symptoma.com]
    Fever
    • A side effect of this treatment is postembolisation syndrome: severe pain and fever however this is easily managed and lasts only a few days.[en.wikipedia.org]
    • Symptoms of hepatitis B or infection may include the following: fever, chills, skin rash, joint pain and inflammation, tiredness, loss of appetite, nausea, pale stools or dark urine, yellowing of the skin, or pain in the upper right side of the stomach[afinitor.com]
    • In about two-thirds of cases it causes symptoms such as abdominal or flank pain, hematuria, or chills and fever.[ispub.com]
    • Hypertension and fever has been reported 8,12 .[jpma.org.pk]
    • Other symptoms may include fever, vomiting, anaemia, renal failure and hypotension [ 3 ].[jmedicalcasereports.com]
    Pain
    • The procedure can be very painful, so analgesics are used.[en.wikipedia.org]
    • Also, some patients manifest symptoms like lower back and flank pain (in case of renal AML), upper abdominal pain, early satiety and a feeling of fullness (due to hepatic AML).[symptoma.com]
    • Tell your health care provider if you have pain, discomfort, or open sores in your mouth.[afinitor.com]
    • Two months previously he was investigated for chest pain and was found to be in atrial fibrillation.[casesjournal.biomedcentral.com]
    • Occasionally angiomyolipomas can cause abdominal pain or back pain when they grow large in size or start bleeding.[newyorkurologyspecialists.com]
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  • gastrointestinal
    Abdominal Mass
    • Giant renal angiomyolipoma: unusual cause of huge abdominal mass.[epainassist.com]
    • However, patients can present with flank pain, hematuria, hemorrhage, or a tender abdominal mass.[ctisus.com]
    • The majority of this kind of tumor, are often solitary, the mean age of presentation is 43 years, 4 times more common in men and, interestingly, involve the right kidney [ 3 ] Palpable abdominal mass, hematuria or flank pain are the main symptoms, and[casesjournal.com]
    • The most common signs and symptoms are abdominal pain, palpable abdominal mass, hematuria and other consequences of intra-tumoral hemorrhage 7 .[scielo.br]
    Abdominal Pain
    • Affected patients may present with sudden-onset abdominal pain and hemorrhagic shock.[symptoma.com]
    • pain (due to hemorrhage) most common presenting symptom Hematuria (40%) Palpable mass (47%) Shock (due to massive retroperitoneal hemorrhage) Imaging findings Mostly small lesions 5 cm in diameter Many have a large exophytic component (25%) Calcifications[learningradiology.com]
    • Occasionally angiomyolipomas can cause abdominal pain or back pain when they grow large in size or start bleeding.[newyorkurologyspecialists.com]
    • For this to occur, it is imperative to consider the diagnosis early in warfarinized patients (and others at risk of bleeding) who present with abdominal pain.[casesjournal.biomedcentral.com]
    • Side effects linked to Afinitor therapy included upper respiratory infection, swelling of the limbs, joint pains, abdominal pain, diarrhea , headache , couch, vomiting, nausea, sore mouth, inflamed mouth, and acne or eczema . 15% of the women on Afinitor[medicalnewstoday.com]
    Early Satiety
    • Accordingly, hepatic AML may provoke upper abdominal pain, sensations of early satiety and fullness.[symptoma.com]
    Nausea
    • If the dilated blood vessels in an angiomyolipoma rupture, the resulting retroperitoneal haemorrhage causes sudden pain, accompanied with nausea and vomiting.[en.wikipedia.org]
    • Symptoms of hepatitis B or infection may include the following: fever, chills, skin rash, joint pain and inflammation, tiredness, loss of appetite, nausea, pale stools or dark urine, yellowing of the skin, or pain in the upper right side of the stomach[afinitor.com]
    • Case presentation We report a case of a 28 years old woman, in 33 week of her first pregnancy who came to our hospital complaining of abdominal pain in the right hemiabdomen, associated with nausea and vomiting.[casesjournal.com]
    • Side effects linked to Afinitor therapy included upper respiratory infection, swelling of the limbs, joint pains, abdominal pain, diarrhea , headache , couch, vomiting, nausea, sore mouth, inflamed mouth, and acne or eczema . 15% of the women on Afinitor[medicalnewstoday.com]
    • Her symptoms had worsened since the past month and had become associated with generalized weakness, anorexia, nausea and vomiting.[jpma.org.pk]
    Upper Abdominal Pain
    • Accordingly, hepatic AML may provoke upper abdominal pain, sensations of early satiety and fullness.[symptoma.com]
    Vomiting
    • If the dilated blood vessels in an angiomyolipoma rupture, the resulting retroperitoneal haemorrhage causes sudden pain, accompanied with nausea and vomiting.[en.wikipedia.org]
    • Case presentation We report a case of a 28 years old woman, in 33 week of her first pregnancy who came to our hospital complaining of abdominal pain in the right hemiabdomen, associated with nausea and vomiting.[casesjournal.com]
    • Side effects linked to Afinitor therapy included upper respiratory infection, swelling of the limbs, joint pains, abdominal pain, diarrhea , headache , couch, vomiting, nausea, sore mouth, inflamed mouth, and acne or eczema . 15% of the women on Afinitor[medicalnewstoday.com]
    • Her symptoms had worsened since the past month and had become associated with generalized weakness, anorexia, nausea and vomiting.[jpma.org.pk]
    • Other common side effects include: Infections Nausea and vomiting Diarrhea and constipation Swelling of your hands, arms, legs, and feet Joint pain Cough Skin problems (such as rash, acne, or dry skin) Fever Feeling tired Anxiety, aggression, and other[afinitor.com]
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  • musculoskeletal
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  • urogenital
    Flank Pain
    • Case presentation A 41-year-old woman was admitted to the emergency department of our hospital because of acute right flank pain.[casereports.bmj.com]
    • Clinical manifestations usually include flank pain, a palpable mass, gross hematuria and hypovolemic shock.[ckj.oxfordjournals.org]
    • CASE SUMMARY A 63-year-old female patient with history of end-stage renal disease (ESRD) and tuberous sclerosis presented to the emergency department (ED) with right flank pain.[appliedradiology.com]
    • L.M.N. a 47 year old diabetic, hypertensive female presented in the outpatient clinic for evaluation for right sided flank pain of 5 months duration.[jpma.org.pk]
    • In the case of symptomatic AML, patients may present with lower back and flank pain radiating from the affected kidney(s).[symptoma.com]
    Hematuria
    • Frequent urinary tract infections Hematuria- Microscopic hematuria observed during early phase and frank hematuria is seen during late stage.[epainassist.com]
    • The patient was hemodynamically stable without hematuria, lumbar pain or other urological symptoms.[casesjournal.com]
    • […] multiple May be only evidence of tuberous sclerosis Mean age of incidence: teens Equal incidence in males and females Signs and symptoms Small lesions are asymptomatic (60%) Acute flank / abdominal pain (due to hemorrhage) most common presenting symptom Hematuria[learningradiology.com]
    • Presentation with life-threatening hematuria, the so-called Wunderlich syndrome, is fortunately very rare.[cancernetwork.com]
    • Clinical manifestations usually include flank pain, a palpable mass, gross hematuria and hypovolemic shock.[ckj.oxfordjournals.org]
    Kidney Failure
    • Angiomyolipomas rarely cause symptoms, but may bleed or grow large enough to be painful or cause kidney failure.[cancer.gov]
    • These growing tumors may lead to life-threatening complications, such as internal bleeding and kidney failure.[novartisoncology.com]
    • Kidney Failure: Patients taking AFINITOR may develop kidney failure.[afinitor.com]
    • As the tumors grow, they compress the kidneys, leading to bleeding and kidney failure. mTOR kinase, a protein, plays a major role in the growth and development of several non-cancerous tumors linked to TSC.[medicalnewstoday.com]
    • failure - rare more complications...»[rightdiagnosis.com]
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  • Workup

    Diagnostic imaging allows for the detection of space-occupying masses in kidneys, liver or other tissues, and such findings often prompt a tentative diagnosis of tumor disease. Echography, magnetic resonance imaging, and computed tomography scans may also be carried out to determine the dimensions of such a mass and to ascertain which tissues are involved. Here, AML may appear as heterogenous tissue with a variable content of fat. It should be noted, though, that certain subtypes of AML have low-fat contents, and that malignant neoplasms may occasionally contain adipose tissue. These facts limit sensibility and specificity of imaging techniques for AML diagnosis, but renal or hepatic masses containing fat are considered highly suspicious of this type of tumor. Angiography may reveal those masses to be highly vascularized, another feature typical of AML. Arteries usually follow tortuous, irregular courses, and veins have been described to have a whorled, sunburst-like appearance [16]. Arteriovenous shunting and aneurysms are frequently observed.

    Despite their characteristic appearance, AML are frequently misdiagnosed as lipoma, liposarcoma, renal cell carcinoma or hepatocellular carcinoma, or hemangioma. Thus, only histopathological analyses of tumor specimens, possibly combined with subsequent immunohistochemistry staining, allow for a definitive diagnosis of AML. Fine needle aspiration has been proposed to this end, but due to the heterogeneity of AML, findings largely depend on the site of sampling [17] [18].

    Laboratory

    Serum
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  • Imaging

    CT
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  • Ultrasound
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  • Treatment

    Treatment of AML depends on the overall condition of the patient, on whether the lesion is symptomatic or not, on the size of the tumor and angiographic findings. For small, asymptomatic AML, a conservative approach is usually recommended [17]. Cryoablation or radiofrequency ablation may be applied to this end; administration of mTOR inhibitors has also yielded promising results [19]. Either embolization of the renal artery or surgery may be indicated in case of larger, symptomatic renal AML. Embolization of the renal artery is a prophylactic measure aiming at reducing the threat imposed by spontaneous hemorrhages due to rupture of aneurysms. This minimally invasive procedure has traditionally been performed if the tumor size exceeded 4 cm, but angiographic findings should be considered when evaluating the possibility of embolization in the case of smaller tumors [20]. Similarly, larger tumors with low vascularity may not require embolization. Of note, embolization is less frequently used to treat hepatic AML. There is no general consensus as to the preference of embolization over early surgery or vice versa [21]. Removal of neoplastic tissue is usually curative, but patients diagnosed with epithelioid AML should be considered for adjuvant therapy [12]. With regards to renal AML, wedge resection or partial nephrectomy is preferred over total nephrectomy. Renal parenchyma should be preserved as much as possible.

    Prognosis

    Prognosis for AML patients is generally good. Retrospective studies have shown low rates of recurrence; malignant transformation and metastasis have only been described in occasional case reports. However, epithelioid AML may be associated with a less favorable prognosis. Literature holds contradictory information to that end: While in one study, all patients affected by epithelioid AML were found to have "died of neoplastic progression of the disease, with liver, lung and bone metastases" [12], other authors state the "the rate of aggressive behaviour among epithelioid angiomyolipomas (to be) very low" [13].

    Complications

    Aneurysm
    • Arteriovenous shunting and aneurysms are frequently observed.[symptoma.com]
    • A ruptured aneurysm in an angiomyolipoma leads to blood loss that must be stopped (though embolisation) and compensated for (through intravenous fluid replacement).[en.wikipedia.org]
    • In addition, intralesional aneurysmal formations on the CT scan can lead to a greater possibility of tumor rupture [ 3 ].[ckj.oxfordjournals.org]
    • View Article PubMed Google Scholar Yamakado K, Tanaka N, Nakagawa T: Renal angiomyolipoma: relationships between tumor size, aneurysm formation, and rupture.[jmedicalcasereports.com]
    • […] dilated calyces MRI findings Intra-tumoral fat seen with fat-suppression technique Variable areas of high signal intensity on T1WI Angiographic findings Hypervascular mass (95%) Enlarged interlobar interlobular feeding arteries Tortuous, irregular, aneurysmal[learningradiology.com]
    Angiomyolipoma
    • The angiomyolipoma can grow rapidly.[en.wikipedia.org]
    • Misdiagnosis of Angiomyolipoma Failure to diagnose Angiomyolipoma Hidden causes of Angiomyolipoma (possibly wrongly diagnosed) Undiagnosed: Angiomyolipoma Angiomyolipoma: Complications Review possible medical complications related to Angiomyolipoma: Kidney[rightdiagnosis.com]
    • “Hyperattenuating angiomyolipoma is now the preferred term to describe a lesion that was originally described as an “angiomyolipoma with minimal fat”; these lesions represent approximately 4–5% of all angiomyolipomas .[ctisus.com]
    Hypotension
    • After a couple of hours she was developed an episode of fetal bradycardia, hypotension, and a hematocrit continued to decline, despite repeated blood transfusion, which combined with symptoms of intense lumbar pain and hematuria.[casesjournal.com]
    • Nonenhanced computed tomography (CT) scan obtained in a 28-year-old pregnant woman (at 26 weeks' gestation) who presented with sudden-onset right upper quadrant abdominal pain and hypotension.[emedicine.medscape.com]
    • Other symptoms may include fever, vomiting, anaemia, renal failure and hypotension [ 3 ].[jmedicalcasereports.com]
    Retroperitoneal Hemorrhage
    • Radical nephrectomy is required when the patient is hemodynamic unstable, due to retroperitoneal hemorrhage [ 10 ].[casesjournal.com]
    • […] of incidence: teens Equal incidence in males and females Signs and symptoms Small lesions are asymptomatic (60%) Acute flank / abdominal pain (due to hemorrhage) most common presenting symptom Hematuria (40%) Palpable mass (47%) Shock (due to massive retroperitoneal[learningradiology.com]
    • Retroperitoneal hemorrhage from the AML can lead to shock in up to 20% of the patients.[circ.ahajournals.org]
    • CT is a good choice of imaging modalities because it is sensitive to demonstrating a fat-containing renal mass with perirenal and retroperitoneal hemorrhage, which is characteristic of Wunderlich’s syndrome due to spontaneous angiomyolipoma rupture.[ckj.oxfordjournals.org]
    • The clinical presentation needing urgent investigation and treatment is spontaneous retroperitoneal hemorrhage.[epainassist.com]
    Shock
    • […] tuberous sclerosis Mean age of incidence: teens Equal incidence in males and females Signs and symptoms Small lesions are asymptomatic (60%) Acute flank / abdominal pain (due to hemorrhage) most common presenting symptom Hematuria (40%) Palpable mass (47%) Shock[learningradiology.com]
    • Affected patients may present with sudden-onset abdominal pain and hemorrhagic shock.[symptoma.com]
    • Retroperitoneal hemorrhage from the AML can lead to shock in up to 20% of the patients.[circ.ahajournals.org]
    • Clinical manifestations usually include flank pain, a palpable mass, gross hematuria and hypovolemic shock.[ckj.oxfordjournals.org]
    • There are also instances of shock as a result of the hemorrhage of the vessels due to Angiomyolipoma.[epainassist.com]
    Tuberous Sclerosis
    • In tuberous sclerosis, typically many angiomyolipomas affecting each kidney.[en.wikipedia.org]
    • The classic triad of tuberous sclerosis consists of adenoma sebaceum, seizures, and mental retardation, but is only seen in one-third of patients.Major features of tuberous sclerosis include facial angiofibromas, cortical tubers, subependmal nodules,[appliedradiology.com]
    • Comprehensive imaging manifestations of tuberous sclerosis.[ctisus.com]
    Urinary Tract Infection
    • Frequent urinary tract infections Hematuria- Microscopic hematuria observed during early phase and frank hematuria is seen during late stage.[epainassist.com]
    • Patients may present with numerous other symptoms and signs 2 , e.g. palpable mass, flank pain, urinary tract infections, haematuria, renal failure, or hypertension 3 .[radiopaedia.org]
    • Updated safety information from 112 patients treated with AFINITOR for a median duration of 3.9 years identified the following additional adverse reactions: urinary tract infection (31%), abdominal pain (16%), pruritus (12%), gastroenteritis (12%), myalgia[hcp.novartis.com]
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  • Etiology

    AML are tumors mainly composed of adipose tissue, smooth muscle cells, vascular structures. Most cases are deemed sporadic, but about 20% of AML are encountered in TSC patients. TSC is a hereditary disease caused by mutations in either of the two tumor suppressor genes TSC1 and TSC2. These genes encode for hamartin and tuberin, respectively, and those proteins form a complex that inhibits the mTOR pathway. The respective signaling cascade has been shown to affect adipogenesis and angiogenesis, although it is more commonly related to the metabolism of striated muscle cells than to smooth musculature [4]. The mTOR pathway, more precisely the mTOR1 and mTOR2 pathways, depend on diverse stimulators and inhibitors, namely on nutrient and energy supply, the availability of oxygen, cytokines and growth factors, and regulate cell growth, division, differentiation, and death. Since histopathologically, there are no differences between sporadic and TSC-associated AML, it is tempting to speculate that at least part of those "sporadic cases" may be ascribed to gene defects associated with alterations of the mTOR signaling cascade [5]. Such has been proven for pulmonary lymphangioleiomyomatosis [6], a disease that may be accompanied by AML. Loss of heterogeneity of TSC1 and TSC2 has also been confirmed for hepatic AML [2].

    Epidemiology

    The overall incidence of AML has been estimated to be 0.3%, and this value is based on the detection of such tumors in autopsy studies. Women are affected more significantly than men [7].

    About one in five cases can be related to TSC, with 80% and 30% of people diagnosed with this hereditary disorder developing renal and hepatic AML, respectively. Due to the prominent role of TSC in AML etiology, selected epidemiological data shall be presented in consideration of this disease: Most patients are middle-aged women, and the median age at diagnosis of sporadic AML is 49 years, while TSC patients developing AML have a median age of 26 years. As for sporadic AML, only 5% of patients present with bilateral tumors, but TSC is associated with bilateral AML in virtually all cases [7].

    Sex distribution
    Age distribution

    Pathophysiology

    Nowadays, AMLs are generally classified as PEComas, i.e., they are assumed to originate from degenerated perivascular epithelioid cells. At first glance, it may seem unlikely for AML to have a clonal origin, yet recent findings support that hypothesis and argue against the classical theory of AML being congenital malformations or hamartomatous polyclonal neoplasms [8]. Chromosomal aberrations are common, yet very heterogeneous if tumor specimens obtained from different patients are compared [9].

    AML mainly consist of adipose tissue, smooth muscle cells, and vascular fragments. Depending on the prevailing tissue and the tumor's fat content as observed histopathologically, four subtypes of AML may be distinguished: lipomatous (≥70% fat), myomatous (≤10% fat), angiomatous and mixed [10]. An evaluation of smooth muscle cell morphology allows for an even more precise classification of AML, and these cells may appear spindle-shaped, be of the intermediate form, epithelioid or pleomorphic [11].

    The afore-described subtypes differ with regards to their gene expression profiles, and presumably, chromosomal anomalies correlate with tissue composition, architectural features, and growth behaviour. While information regarding the prognostic value of an exact histopathological characterization is still scarce, epithelioid AML have been proposed to be re-classified as malignant neoplasms [12].

    Prevention

    No specific measures can be recommended to prevent AML. However, patients suffering from TSC may undergo regular screening to detect mesenchymal tumors during early stages. Then, therapy may be initiated before aneurysms develop within AML and the patient's risk of life-threatening hemorrhages due to aneurysm rupture can be diminished.

    Summary

    Angiomyolipoma (AML) is a benign mesenchymal tumor. It derives the name from its characteristic histopathological properties: mature adipose tissue, spindle-shaped smooth muscle cells and branched vessels prone to dilation and rupture. The most common subtype of AML is renal AML, and there are several hundred case reports concerning hepatic AML. Extrarenal, non-hepatic AML are extremely rare. While most cases are sporadic, it has been estimated that one in five cases of renal AML and one in ten cases of hepatic AML corresponds to manifest tuberous sclerosis (TSC). Moreover, renal AML are very common in TSC; hemorrhages due to rupture of aneurysms forming in AML are the leading cause of death in patients suffering from this genetic disorder [1]. Hepatic lesions, namely hepatic AML, adenoma, hemangioma and hepatic cysts are detected in about 30% of TSC patients [2]. Moreover, AML may be observed in patients diagnosed with lymphangioleiomyomatosis, neurofibromatosis type 1 and Von Hippel-Lindau disease [3].

    The clinical presentation of AML patients varies largely and ranges from asymptomatic condition to abdominal pain to hemorrhagic shock. Most patients are indeed asymptomatic and here, AML is usually an accidental finding. Imaging techniques may reveal a space-occupying mass in renal, hepatic or other tissues, and may provide valuable information as to the properties of that mass. Nevertheless, only histopathological features are considered diagnostic of AML. Therapeutic strategies are adapted to the individual case and primarily depend on tumor size and the presence of aneurysms prone to rupture.

    Patient Information

    Angiomyolipoma (AML) is a benign neoplasm most commonly encountered in kidneys and liver. Its name is derived from its main components: branched vessels, smooth muscle cells and fat. Its etiology is only poorly understood, but considerable shares of AML patients suffer from tuberous sclerosis or lymphangioleiomyomatosis.

    Women are affected significantly more often than men, and their median age at the time of diagnosis is 49 years. AML may be diagnosed incidentally, if images of the abdominal cavity are obtained for non-related reasons. Also, some patients manifest symptoms like lower back and flank pain (in case of renal AML), upper abdominal pain, early satiety and a feeling of fullness (due to hepatic AML). Tumors may interfere with organ function and patients may note blood in their urine. Rarely, sudden-onset abdominal pain and shock due to blood loss may prompt a suspicion of AML. The latter symptoms result from the rupture of vessels passing through the tumor.

    Although life-threatening blood loss is a rare event in AML patients, it still poses a major threat. Consequently, treatment aims at eliminating this threat. This can be achieved by arterial embolization, i.e., by occlusion of the artery that supplies blood to the tumor. Another approach to AML treatment consists in the surgical removal of neoplastic tissue. Surgery is often curative, but tissue preservation may be better if a conservative approach and embolization are chosen. Preference of either therapy depends on the overall condition of the patient, on whether the lesion is symptomatic or not, on the size of the tumor and angiographic findings. Of note, current research is focused on drug therapy of AML, but to date, medication is not considered a first-line treatment option.

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    References

    1. Brakemeier S, Bachmann F, Budde K. Treatment of renal angiomyolipoma in tuberous sclerosis complex (TSC) patients. Pediatr Nephrol. 2016.
    2. Huang SC, Chuang HC, Chen TD, et al. Alterations of the mTOR pathway in hepatic angiomyolipoma with emphasis on the epithelioid variant and loss of heterogeneity of TSC1/TSC2. Histopathology. 2015; 66(5):695-705.
    3. Lowe LH, Isuani BH, Heller RM, et al. Pediatric renal masses: Wilms tumor and beyond. Radiographics. 2000; 20(6):1585-1603.
    4. Laplante M, Sabatini DM. mTOR signaling in growth control and disease. Cell. 2012; 149(2):274-293.
    5. Kenerson H, Folpe AL, Takayama TK, Yeung RS. Activation of the mTOR pathway in sporadic angiomyolipomas and other perivascular epithelioid cell neoplasms. Hum Pathol. 2007; 38(9):1361-1371.
    6. Kristof AS. mTOR signaling in lymphangioleiomyomatosis. Lymphat Res Biol. 2010; 8(1):33-42.
    7. Seyam RM, Bissada NK, Kattan SA, et al. Changing trends in presentation, diagnosis and management of renal angiomyolipoma: comparison of sporadic and tuberous sclerosis complex-associated forms. Urology. 2008; 72(5):1077-1082.
    8. Paradis V, Laurendeau I, Vieillefond A, et al. Clonal analysis of renal sporadic angiomyolipomas. Hum Pathol. 1998; 29(10):1063-1067.
    9. Katter MM, Grignon DJ, Eble JN, et al. Chromosomal analysis of renal angiomyolipoma by comparative genomic hybridization: evidence for clonal origin. Hum Pathol. 1999; 30(3):295-299.
    10. Agaimy A, Vassos N, Croner RS, Strobel D, Lell M. Hepatic angiomyolipoma: a series of six cases with emphasis on pathological-radiological correlations and unusual variants diagnosed by core needle biopsy. Int J Clin Exp Pathol. 2012; 5(6):512-521.
    11. Nonomura A, Enomoto Y, Takeda M, Takano M, Morita K, Kasai T. Angiomyolipoma of the liver: a reappraisal of morphological features and delineation of new characteristic histological features from the clinicopathological findings of 55 tumours in 47 patients. Histopathology. 2012; 61(5):863-880.
    12. Varma S, Gupta S, Talwar J, Forte F, Dhar M. Renal epithelioid angiomyolipoma: a malignant disease. J Nephrol. 2011; 24(1):18-22.
    13. He W, Cheville JC, Sadow PM, et al. Epithelioid angiomyolipoma of the kidney: pathological features and clinical outcome in a series of consecutively resected tumors. Mod Pathol. 2013; 26(10):1355-1364.
    14. Northrup H, Krueger DA. Tuberous sclerosis complex diagnostic criteria update: recommendations of the 2012 Iinternational Tuberous Sclerosis Complex Consensus Conference. Pediatr Neurol. 2013; 49(4):243-254.
    15. Soulen MC, Faykus MH, Jr., Shlansky-Goldberg RD, Wein AJ, Cope C. Elective embolization for prevention of hemorrhage from renal angiomyolipomas. J Vasc Interv Radiol. 1994; 5(4):587-591
    16. Davis C, Boyett T, Caridi J. Renal artery embolization: application and success in patients with renal cell carcinoma and angiomyolipoma. Semin Intervent Radiol. 2007; 24(1):111-116.
    17. Pancholi V, Munjal K, Jain M, Munjal S, Agrawal R, Nandedkar S. Preoperative diagnosis of renal angiomyolipoma with fine needle aspiration cytology: a report of 3 cases. Acta Cytol. 2006; 50(4):466-468.
    18. Zeng JP, Dong JH, Zhang WZ, Wang J, Pang XP. Hepatic angiomyolipoma: a clinical experience in diagnosis and treatment. Dig Dis Sci. 2010; 55(11):3235-3240.
    19. Bissler JJ, McCormack FX, Young LR, et al. Sirolimus for angiomyolipoma in tuberous sclerosis complex or lymphangioleiomyomatosis. N Engl J Med. 2008; 358(2):140-151.
    20. Kuusk T, Biancari F, Lane B, et al. Treatment of renal angiomyolipoma: pooled analysis of individual patient data. BMC Urol. 2015; 15:123.
    21. Faddegon S, So A. Treatment of angiomyolipoma at a tertiary care centre: the decision between surgery and angioembolization. Can Urol Assoc J. 2011; 5(6):E138-141.



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    1. Angiomyolipome der Niere CT, CC BY-SA 3.0

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