Colon (tumor & nontumor)
Mesenchymal tumors
Idiopathic retroperitoneal fibrosis

Topic Completed: 1 December 2016

Minor changes: 31 July 2020

Copyright: 2003-2019,, Inc.

PubMed Search: retroperitoneal fibrosis [title] colon

Raul S. Gonzalez, M.D.
Page views in 2019: 1,165
Page views in 2020 to date: 875
Cite this page: Gonzalez R. Idiopathic retroperitoneal fibrosis. website. Accessed August 11th, 2020.
Definition / general
  • Nonneoplastic fibrosis that develops in retroperitoneum and may encroach upon colon
Essential features
  • Benign fibrosing process of the retroperitoneum that can rarely involve the gastrointestinal tract secondarily
  • Some cases belong to the spectrum of IgG4 related disease
  • Also called Ormond's disease, idiopathic retroperitoneal fibrosis
  • Arises in retroperitoneum, often at aortic bifurcation
  • Gastrointestinal tract involvement is rare
  • IgG4 positive plasma cells implicated as a causative factor (Am J Surg Pathol 2009;33:1833); can also be caused by methysergide or lymphoma, or may be idiopathic
Clinical features
  • Increased serum IgG and IgG4 in patients with IgG4 related disease
Case reports
Clinical images

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Retroperitoneal mass enveloping aorta

Gross description
  • Poorly circumscribed fibrotic mass
Microscopic (histologic) description
  • Storiform fibrotic process infiltrated by eosinophils and IgG4 positive plasma cells (which may be sparse)
  • May show obliterative phlebitis, fat necrosis
  • Similar findings may be observed in lymph nodes (Am J Clin Pathol 1996;105:430)
Microscopic (histologic) images

Contributed by Raul S. Gonzalez, M.D.
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Various images

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Fibrosis involving ureter

Positive stains
  • IgG4 (in plasma cells)
Differential diagnosis
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