Small bowel (small intestine)

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Small bowel (small intestine)

Benign tumors and tumor-like conditions

Angiomyolipoma

Reviewer: Nat Pernick, M.D. (see Reviewers page)
Revised: 18 December 2012, last major update May 2010
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

See also Kidney-benign chapter

Definition
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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

Etiology
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● Member of 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 description
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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)
● 28 year old man with with ileal intussusception (World J Gastroenterol 2009;15:1398)

Treatment and prognosis
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● Typically benign behavior at other sites, but occasionally is invasive with 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

Various images

Micro 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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Various images

Positive stains
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● HMB45 and MelanA / A103, SMA, calponin, CD117, 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

End of Small bowel (small intestine) > Benign tumors and tumor-like conditions > Angiomyolipoma

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