title: Reactive nodular fibrous pseudotumors of the gastrointestinal tract: report of 8 cases.
abstract: Eight cases of reactive nodular fibrous pseudotumor of the gastrointestinal tract are presented. The patients included 6 males and 2 females between the ages of 1 and 68 years (mean age 41.5 years). Three tumors involved the small intestine, and 5 of the investigated lesions were located in the large bowel. Of these, 2 originated in the sigmoid colon, 1 in the cecum, 1 in the appendix, and 1 in the large bowel not otherwise specified. The tumors' size varied from 3 to 10 cm in the greatest diameter (mean 6.2 cm). Histologically they were composed of stellate or spindle shaped cells resembling fibroblasts arranged haphazardly or in intersecting fascicles, embedded in a collagen-rich stroma, with sparse intralesional mononuclear cells frequently arranged in lymphoid aggregates. Immunohistochemically, the lesions were positive for vimentin (7/7), smooth muscle actin (8/8), muscle-specific actin (5/7), cytokeratins AE1/AE3 (6/7), and CAM 5.2 (1/7), and antigen CD68 (1/7). No case (0/8) reacted positively with antibody to CD117 (c-kit). Genetically no substitutions, deletions, or insertions occurred in exon 11 in all analyzed samples. Likewise, no deletions or insertions in part of exon 9 were observed. Ultrastructurally the tumor cells revealed features typical of myofibroblasts. According to the morphologic, immunohistochemical, and ultrastructural features mentioned above, especially to the positivity of low-molecular-weight cytokeratins, we propose this lesion to be related to a proliferation of multipotential subserosal cells rather than ordinary myofibroblasts or fibroblasts.
authors.affiliation: Department of Pathology, Medical Faculty Hospital, Plzen, Czech Republic.
authors.forename: Ondrej
authors.initials: O
authors.lastname: Daum
authors.forename: Tomas
authors.initials: T
authors.lastname: Vanecek
authors.forename: Radek
authors.initials: R
authors.lastname: Sima
authors.forename: Romuald
authors.initials: R
authors.lastname: Curik
authors.forename: Michal
authors.initials: M
authors.lastname: Zamecnik
authors.forename: Shoji
authors.initials: S
authors.lastname: Yamanaka
authors.forename: Petr
authors.initials: P
authors.lastname: Mukensnabl
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Benes
authors.forename: Michal
authors.initials: M
authors.lastname: Michal
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis; D005260:Female; D005355:Fibrosis / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D005767:Gastrointestinal Diseases / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers