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Colon tumor

Mesenchymal tumors

Reactive nodular fibrous pseudotumor of colon

Reviewers: Charanjeet Singh, M.D. (see Reviewers page)
Revised: 16 May 2012, last major update May 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.


● First described in 2003 in 5 patients (Am J Surg Pathol 2003;27:532)
● Mean age 56 years, range 48 to 71 years
● Associated with prior abdominal surgery
● At other sites, associated with endometriosis and ergotamine derivatives (Virchows Arch 2005;447:879)
● May be related to a proliferation of multipotential subserosal cells (Int J Surg Pathol 2004;12:365)
Symptoms: acute abdominal pain, abdominal mass or incidental lesion
Genetics: despite staining for CD117, there are no substitutions, deletions or insertions in exon 11 or exon 9 of c-kit

Case reports

● 60 year old man with reactive nodular fibrous pseudotumor in gastric wall (Gastroenterol Clin Biol 2009;33:1076)


● Complete resection appears curative

Gross description

● Multiple or solitary tumors, usually involving outer wall of small intestine or colon
● Firm, tan-white, 3-10 cm and well-circumscribed

Micro description

● Low to moderately cellular, composed of stellate or spindled fibroblasts arranged haphazardly or in intersecting fascicles
● May have infiltrative borders
● Stroma rich in collagen (wire-like, keloidal or hyalinized)
● Sparse intralesional mononuclear cells and peripheral lymphoid aggregates are usually present

Positive stains

● CD117 (80%), smooth muscle actin, muscle specific actin or desmin (60%), vimentin, cytokeratin AE1-AE3, CAM 5.2 and CD68

Negative stains

● CD34, S100, ALK1 and caldesmon

Electron microscopy description

● Myofibroblasts

Differential diagnosis

● Retroperitoneal fibrosis: disease of retroperitoneum, associated with Reidelís sclerosing thyroiditis, methylsergine
● Sclerosing mesenteritis: involves mesentery or mesocolon, mean 10 cm but up to 40 cm, usually no prior trauma, thick collagen bands dissecting lobules of mesenteric fat with fat necrosis

End of Colon tumor > Mesenchymal tumors > Reactive nodular fibrous pseudotumor of colon

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