Appendix
Benign tumors
Fibrous obliteration

Reviewer: Jaleh Mansouri, M.D. (see Authors page)

Revised: 23 February 2016, last major update August 2012

Copyright: (c) 2003-2016, PathologyOutlines.com, Inc.

PubMed Search: Fibrous obliteration appendix
Definition / General
  • Also called appendiceal neuroma, neuronal hyperplasia
  • Common, in 27% of surgical specimens (Am J Surg Pathol 1986;10:801)
  • Gross Description
  • Usually no gross tumor
  • Usually affects distal tip, may affect entire lumen
  • Micro Description
  • Lumen replaced by spindle cells in loose fibromyxoid background with chronic inflammatory cells (including eosinophils), hypertrophied nerve bundles, neuroendocrine cells, fat and collagen
  • Loss of lymphoid follicles, mucosa and crypts
  • Spindle cells may expand the lamina propria and separate the crypts
  • Intramucosal neuroma: primarily affects the mucosa, does not obliterate the lumen
  • Positive Stains
    Spindle cells:
  • S100, chromogranin, neuron specific enolase
  • Electron Microscopy Description
  • Spindle cells resemble Schwann cells
  • Differential Diagnosis
  • Carcinoid tumor: definite insular pattern of neoplastic cells, extending into muscularis propria, associated with gross nodule or thickening of appendiceal wall