Small bowel (small intestine)
Benign tumors and tumor-like conditions
Idiopathic retroperitoneal fibrosis

Author: Hanni Gulwani, M.D. (see Authors page)

Revised: 19 February 2018, last major update August 2012

Copyright: (c) 2003-2018, PathologyOutlines.com, Inc.

PubMed Search: Idiopathic retroperitoneal fibrosis small bowel

Cite this page: Gulwani, H. Idiopathic retroperitoneal fibrosis. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/smallbowelIRF.html. Accessed July 15th, 2018.
Definition / general
  • Fibrosis which develops in retroperitoneum, often at aortic bifurcation
  • Associated with drug methylsergine, other fibrotic lesions (sclerosis of major bile ducts, Riedel thyroiditis, inflammatory pseudotumor of orbit)
  • IgG4 often involved in pathogenesis of idiopathic sclerosing lesion; associated with male gender
  • Associated with lymphoma, which developed in 15% of patients
Case reports
Gross description
  • Not well circumscribed
Microscopic (histologic) description
  • Widely scattered germinal centers and plasma cells in background of dense fibrosis
  • Eosinophilic infiltration and oblitertaive phlebitis in IgG4 related cases (Am J Surg Pathol 2009;33:1833)