title: Co-expression of neuronal intermediate filaments, peripherin and α-internexin in human well-differentiated endocrine neoplasms (carcinoid tumors) of the appendix.
abstract: The rectum and appendix are the two major sites of well-differentiated endocrine neoplasms (carcinoid tumors) in the lower gastrointestinal tract. Previously, we reported the consistent expression of peripherin in rectal well-differentiated endocrine neoplasms without metastases. However, its expression has not as yet been examined in appendiceal well-differentiated endocrine neoplasms. The aim of our present study was to clarify whether peripherin, a type III neuronal intermediate filament, and α-internexin, a type IV neuronal intermediate filament, are expressed in appendiceal well-differentiated endocrine neoplasms. Other endocrine markers were also examined and compared with the findings from the rectal well-differentiated endocrine neoplasms. The analyses were carried out by immunohistochemical methods using 12 formalin-fixed and paraffin-embedded appendiceal well-differentiated endocrine neoplasms. In all the neoplasms examined, diffuse immunoreactivity of peripherin was observed. In addition, immunoreactivity of α-internexin, which was frequently co-expressed with peripherin, was found in all appendiceal cases. Chromogranin A and neural cell adhesion molecule expression was found in all appendiceal tumors, and serotonin was also frequently expressed (83%, 10/12 cases). Incidences of the expression of these three markers were much higher in the appendiceal than in the rectal cases. Peripherin expression is a common feature of appendiceal and rectal well-differentiated endocrine neoplasms, but the manner of neural marker expression is different depending on the site of origin. It is uncertain whether the expression of peripherin and/or α-internexin is present in the well-differentiated endocrine neoplasms of other organs; further analysis is required to clarify this issue.
authors.affiliation: Department of Clinical Laboratory Medicine, Shiga University of Medical Science, Shiga 520-2192, Japan.
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Ishida
authors.forename: Ryoji
authors.initials: R
authors.lastname: Kushima
authors.forename: Marie
authors.initials: M
authors.lastname: Brevet
authors.forename: Denis
authors.initials: D
authors.lastname: Chatelain
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Okabe