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Table of Contents
Definition / general | Case reports | Treatment | Gross description | Microscopic (histologic) description | Positive stains | Negative stains | Electron microscopy description | Differential diagnosisCite this page: Reactive nodular fibrous pseudotumor. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/colontumorreactivenodular.html. Accessed July 14th, 2017.
Definition / general
- 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)
Treatment
- Complete resection appears curative
Gross description
- Multiple or solitary tumors, usually involving outer wall of small intestine or colon
- Firm, tannish white, 3 - 10 cm and well circumscribed
Microscopic (histologic) 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
Electron microscopy description
- Myofibroblasts
Differential diagnosis
- Retroperitoneal fibrosis: disease of retroperitoneum, associated with Reidel's 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
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