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Appendix

Benign tumors

Fibrous obliteration


Reviewer: Jaleh Mansouri, M.D. (see Reviewers page)
Revised: 20 October 2012, last major update August 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● Also called appendiceal neuroma, neuronal hyperplasia
● Common, in 27% of surgical specimens (Am J Surg Pathol 1986;10:801)

Gross description
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● Usually no gross tumor
● Usually affects distal tip, may affect entire lumen

Micro description
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● 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)
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● S100, chromogranin, neuron specific enolase

Electron microscopy description
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● Spindle cells resemble Schwann cells

Differential diagnosis
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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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