Reviewer: Jaleh Mansouri, M.D. (see Reviewers page)
Revised: 20 October 2012, last major update August 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.
● Also called appendiceal neuroma, neuronal hyperplasia
● Common, in 27% of surgical specimens (Am J Surg Pathol 1986;10:801)
● Usually no gross tumor
● Usually affects distal tip, may affect entire lumen
● 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
● Carcinoid tumor: definite insular pattern of neoplastic cells, extending into muscularis propria, associated with gross nodule or thickening of appendiceal wall
End of Appendix > Benign tumors > Fibrous obliteration
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