Angiomyolipoma overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Cafer Zorkun, M.D., Ph.D. [2], Faizan Sheraz, M.D. [3]
Overview
Angiomyolipoma is a benign renal neoplasm previously considered to be a hamartoma or choristoma, but now known to be neoplastic.[1] It is composed of variable amounts of fat, vascular, and smooth muscle elements. The fat density of the tumor on CT has been regarded to be pathognomonic. The lesion is well demarcated and contains mature elements. It occurs in more than 50% of individuals with tuberous sclerosis, often bilaterally. On gross pathology, well circumscribed and uniform yellow mass is characteristic finding of angiomyolipoma. Angiomyolipoma is caused by a defect in the TSC1 gene. Angiomyolipoma must be differentiated from retroperitoneal liposarcoma, adrenal myelolipoma, and renal cell carcinoma. If left untreated, small angiomyolipomas and those without dilated blood vessels (aneurysms) cause few symptoms. Small angiomyolipomas are associated with the most favorable prognosis.Common complications of angiomyolipoma include infection, hematuria and hemorrhage. Abdominal CT scan may be diagnostic for angiomyolipoma. On CT scan, angiomyolipoma is characterized by smooth tumor margin with low intratumoral fat component and homogenous enhancement on both corticomedullary and excretory phase scans.[2] Surgery is not the first-line treatment option for patients with angiomyolipoma. Transcatheter arterial embolization is usually reserved for patients with complicated disease.[3]
Classification
Angiomyolipoma may be classified according to etiology into 2 subtypes: tuberous sclerosis associated angiomyolipoma and isolated angiomyolipoma.
Pathophysiology
On gross pathology, well circumscribed and uniform yellow mass is characteristic finding of angiomyolipoma.
Causes
Angiomyolipoma is caused by a defect in the TSC1 gene. It can also be caused by a defect in another gene:TSC2.
Differentiating Angiomyolipoma from other Diseases
Angiomyolipoma must be differentiated from retroperitoneal liposarcoma, adrenal myelolipoma, and renal cell carcinoma.[4][5]
Epidemiology and Demographics
The incidence of angiomyolipoma is approximately 30 per 100,000 individuals worldwide. Women are more commonly affected with angiomyolipoma than men.
Screening
Patients who have tuberous sclerosis should be screened for angiomyolipoma. Abdominal CT scan is recommended for screening of angiomyolipoma.[5]
Natural History, Complications and Prognosis
If left untreated, small angiomyolipomas and those without dilated blood vessels (aneurysms) cause few symptoms. Small angiomyolipomas are associated with the most favorable prognosis.Common complications of angiomyolipoma include infection, hematuria and retroperitoneal hemorrhage.
History and Symptoms
Symptoms of angiomyolipoma include nausea, vomiting, and abdominal pain.
Physical Examination
Common physical examination findings of angiomyolipoma include fever, flank tenderness, and palpable mass.
Laboratory Findings
Laboratory findings consistent with the diagnosis of angiomyolipoma include presence of blood cells in urine and elevated white blood cell count.
CT
Abdominal CT scan may be diagnostic for angiomyolipoma. On CT scan, angiomyolipoma is characterized by smooth tumor margin with low intratumoral fat component and homogenous enhancement on both corticomedullary and excretory phase scans.[2]
MRI
Abdominal MRI may be diagnostic of angiomyolipoma. On MRI, angiomyolipoma is characterized by high signal intensity on non-fat saturated sequences, and loss of signal following fat saturation.
Ultrasound
On abdominal ultrasound, angiomyolipoma is characterized by hyperechoic lesions and posterior acoustic shadowing in the cortex.
Other Imaging Studies
On digital subtraction angiography, angiolipoma is characterized by hypervascular lesions, microvascular aneurysms and absent AV shunting.
Medical Therapy
There is no medical therapy for angiomyolipoma; the mainstay of therapy is surgical resection or embolisation.
Surgery
Surgery is not the first-line treatment option for patients with angiomyolipoma. Transcatheter arterial embolization is usually reserved for patients with complicated disease.[3]
References
- ↑ Eble JN. Angiomyolipoma of the kidney. Semin Diagn Pathol 1988;15:21-40
- ↑ 2.0 2.1 Kim JK, Park SY, Shon JH, Cho KS (2004). "Angiomyolipoma with minimal fat: differentiation from renal cell carcinoma at biphasic helical CT". Radiology. 230 (3): 677–84. doi:10.1148/radiol.2303030003. PMID 14990834.
- ↑ 3.0 3.1 Lewis JH, Weingold AB (1985). "The use of gastrointestinal drugs during pregnancy and lactation". Am J Gastroenterol. 80 (11): 912–23. PMID 2864852.
- ↑ Patil, PA.; McKenney, JK.; Trpkov, K.; Hes, O.; Montironi, R.; Scarpelli, M.; Nesi, G.; Aron, M.; Sangoi, AR. (2014). "Renal Leiomyoma: A Contemporary Multi-institution Study of an Infrequent and Frequently Misclassified Neoplasm". Am J Surg Pathol. doi:10.1097/PAS.0000000000000354. PMID 25517956. Unknown parameter
|month=ignored (help) - ↑ 5.0 5.1 Renal angiomyolipoma differential diagnosis. Dr Matt A. Morgan and Dr Behrang Amini et al. Radiopaedia 2015. http://radiopaedia.org/articles/renal-angiomyolipoma