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Small bowel (small intestine)
Angiomyolipoma
Author: Nat Pernick, M.D., PathologyOutlines.com, Inc.
Revised: 9 May 2010
Last major update: May 2010December 2009
Copyright: (c) 2009-2010, PathologyOutlines.com, Inc.
Definition
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● Angiomyolipoma is a benign triphasic tumor composed of dysmorphic, thick walled blood vessels, smooth muscle that appears to spin off from vessel walls, and mature lipid-distended cells
Etiology
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● Angiomyolipoma is a member of the PEComa family, a concept first proposed by Bonetti (Am J Surg Pathol 1992;16:307), which comprises mesenchymal tumors with perivascular clear cells and epithelioid features that coexpress melanocytic and muscle markers
● Occasionally associated with tuberous sclerosis (OMIM #191100)
Clinical
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● Usually arises in the kidney (eMedicine), or occasionally in the liver (Arch Pathol Lab Med 2008;132:1679)
● Gastrointestinal angiomyolipoma is very rare
Case reports
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● First documented case of symptomatic ileal angiomyolipoma was in a 60 year old woman suffering from intermittent periumbilical pain (Korean J Gastroenterol 2000;36:250)
● Second case of ileal angiomyolipoma occurred in a 48 year old woman with vague abdominal pain and bloody stool (J Gastroenterol 2005;40:200)
● 25 year old man with 25 cm small bowel mass (Case of the Week #177)
Treatment and prognosis
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● Angiomyolipoma typically has benign behavior at other sites, but may occasionally be invasive and have metastases (Am J Surg Pathol 1991;15:1083)
Clinical images
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25 cm mass
Gross images
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25 cm mass
Microscopic description
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● Benign triphasic tumor composed of dysmorphic, thick walled blood vessels, smooth muscle that appears to spin off from vessel walls, and mature lipid-distended cells
● Tumors occasionally have bizarre epithelioid smooth muscle cells (Int J Surg Pathol 2000;8:67) and possible multinucleation
Micro images
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Positive stains
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● HMB45 and MelanA / A103, SMA, calponin, CD117, and S100 (Am J Surg Pathol 2002;26:493)
Negative stains
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● Keratin
Differential diagnosis
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● Theoretically broad, encompassing smooth muscle and lipogenic tumors, but narrowed when one carefully identifies the components of the tumor
● Few other tumors are immunoreactive for both smooth muscle and melanocytic markers
● Leiomyomas and leiomyosarcomas have a prominent smooth muscle component, but lack a prominent vascular or adipose component
● Melanomas have prominent atypia, necrosis and infiltrative borders
Additional references
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● PathologyOutlines.com – Kidney Tumor-Adult Benign, World J Gastroenterol 2009;15:1398
End of Colon-nontumor > Small bowel (small intestine) > Angiomyolipoma
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