Colon tumor
Mesenchymal tumors

Topic Completed: 1 July 2016

Revised: 10 June 2019

Copyright: 2002-2019,, Inc.

PubMed Search: Angiomyolipoma [title] OR PEComa [title]

Raul S. Gonzalez, M.D.
Page views in 2019: 760
Page views in 2020 to date: 82
Cite this page: Gonzalez R. Angiomyolipoma. website. Accessed February 23rd, 2020.
Definition / general
  • Angiomyolipoma of colon: rare benign mesenchymal neoplasm, composed of vascular, adipocytic and smooth muscle elements, analogous to its more common counterpart in the kidney
Essential features
  • Angiomyolipoma: bland triphasic mesenchymal neoplasm in the PEComa family; most reported colonic cases have been HMB45 negative (if stained), casting some doubt on the diagnosis
  • Can arise anywhere in the gastrointestinal tract, though colon is most common
Clinical features
  • Patients typically middle aged, with a slight female predominance; they very rarely have tuberous sclerosis
Prognostic factors
  • Marked nuclear atypia, diffuse pleomorphism and high mitotic rate associated with risk of metastasis for PEComa (Am J Surg Pathol 2013;37:1769)
Case reports
Microscopic (histologic) description
  • Angiomyolipoma: bland mural tumor composed of smooth muscle, blood vessel and mature adipose elements
Negative stains
  • Angiomyolipoma: HMB45 negative in nearly all reported examples (Am J Gastroenterol 1996;91:1852), unlike renal angiomyolipoma; this calls the diagnosis into doubt in such cases
Differential diagnosis
  • Alveolar soft part sarcoma: epithelioid, eosinophilic cells arranged in a nested / alveolar pattern; nuclei are bland and are positive for TFE3; all reported colonic cases appear to be metastases
  • Neuromuscular and vascular hamartoma: bland injury related proliferation of smooth muscle, vessels and nerves / ganglia; native fat may be present; more common in small intestine
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