Peripherin is a type III neuronal intermediate filament and its expression is involved in the growth and development of the peripheral nervous systems.
Peripherin expression has been reported in cutaneous endocrine
carcinomas, but not in rectal well-differentiated endocrine
neoplasms (
carcinoid tumors). Well-differentiated endocrine
neoplasms have been reported to have a relatively high incidence of
metastasis, but there is no complete parameter for prediction of their malignant behavior. The aim of the present study was to clarify the expression of
peripherin in human fetal and adult rectal mucosae and rectal well-differentiated endocrine
neoplasms and the significance of
peripherin expression in well-differentiated endocrine
neoplasms. Expression of
peripherin was studied immunohistochemically in 3 fetal hindgut mucosae, 10 non-neoplastic rectal mucosae, 12 rectal well-differentiated endocrine
neoplasms without
metastases, and 5 well-differentiated endocrine
neoplasms with
metastases. Adult rectal mucosal epithelial cells did not have
peripherin. However, transient expression of
peripherin was detected in the subgroup of epithelial cells of the fetal rectum.
Peripherin was demonstrated in all of the rectal well-differentiated endocrine
neoplasms without
metastases (12/12 cases), but was absent from some of the well-differentiated endocrine
neoplasms with
metastases (3/5 cases). Constant expression of
peripherin in rectal well-differentiated endocrine
neoplasms without
metastases (12/12) seems to reflect the phenotype of the subpopulation of epithelial cells confined to the fetal rectum. However, loss of its expression was observed in cases with
metastases (3/5) and can be regarded as an additional parameter to predict the risk of
metastasis in rectal well-differentiated endocrine
neoplasms.