Appendix
Benign tumors
Fibrous obliteration

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

Revised: 23 February 2016, last major update August 2012

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PubMed Search: Fibrous obliteration appendix
Cite this page: Fibrous obliteration. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/appendixfibrousobliteration.html. Accessed August 21st, 2017.
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
  • Microscopic (histologic) 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