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Colon tumor

Mesenchymal tumors

Schwannoma of colon


Reviewers: Charanjeet Singh, M.D. (see Reviewers page)
Revised: 3 May 2012, last major update May 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● Rare; less common than colonic GIST
● Median age 65 years, range 18-87 years; affects men and women equally
● Benign behavior; not associated with neurofibromatosis

Case reports
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● 52 year old man with neurofribromatosis causing intussusception (Thomas Jefferson University 2006)
● 68 year old woman with sigmoid tumor (Kurume Med J 2000;47:165)
● 70 year old man with rectal tumor with synchronous colonic adenocarcinoma (World J Surg Oncol 2005;3:46)
● 72 year old man and 54 year old man with plexiform schwannoma (Mod Pathol 1997;10:1075)
● 2 cases - 73 year old woman and 44 year old man with submucosal tumor (Surg Today 2001;31:833)

Clinical images
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Submucosal colonic tumors

Gross description
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● Well circumscribed but usually not encapsulated, polypoid intraluminal mass 0.5 to 5.5 cm with mucosal ulceration, usually in right colon

Gross images
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Various images

Micro description
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● In soft tissue, encapsulated biphasic nerve sheath tumor derived from Schwann cells with highly ordered cellular component (Antoni A) that palisades (Verocay bodies), plus myxoid component (Antoni B)
● In colon, usually no encapsulated, no / indistinct Verocay bodies, no prominent nuclear palisading (Am J Surg Pathol 2001;25:846)
● Usually trabecular pattern of spindle cells, surrounded by lymphoid cuff
● May have epithelioid or plexiform features
● Often focal nuclear atypia; 0-4 mitotic figures / 50 HPF
● Usually no vascular hyalinization, no xanthoma cells

Micro images
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Various images


Spindle cells

           
Various immunostains

Positive stains
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● S100, GFAP
● May have PAS+ needle-shaped crystalloids (Am J Surg Pathol 1999;23:431)
● Also type 4 collagen, low affinity nerve growth factor receptor (p75)

Negative stains
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● CD117/kit, smooth muscle actin, desmin, CD34 (usually) and Ki-67 (less than 3%)

Differential diagnosis
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GIST: CD117+, CD34+, S100-, no prominent lymphoid infiltration and no microtrabecular pattern
Inflammatory myofibroblastic tumor: spindle cells with abundant amphophilic cytoplasm
Leiomyoma: rare, usually small polyps and positive for smooth muscle markers

End of Colon tumor > Mesenchymal tumors > Schwannoma of colon


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