A comparative immunohistochemical study of jejunoileal and appendiceal carcinoids. Implications for histogenesis and pathogenesis.
BACKGROUND
The purpose of this study was to determine the histogenesis of jejunoileal and appendiceal carcinoids and to ascertain whether this could be useful in further explaining the pathology of these neoplasms.


METHODS
Eight cases each of multiple jejunoileal carcinoids and appendiceal carcinoids together with their respective age-matched and sex-matched controls were stained with silver stains, chromogranin A, serotonin, and S-100. Histomorphometric evaluations of the endocrine cells in the mucosa adjacent to the carcinoids were carried out and compared with the respective controls using the Student's t test.


RESULTS
All the carcinoids from both groups stained for argyrophilia, argentaffinity, chromogranin A, and serotonin. Histomorphometric evaluations showed intraepithelial endocrine cell hyperplasia (IECH) in the jejunoileal carcinoid group (P = 0.007, chromogranin; P = 0.004, serotonin) but not in the appendiceal carcinoid group. On the other hand, subepithelial endocrine cell aggregates that were separate from the main tumor were seen in two cases of appendiceal carcinoids. With S-100, all appendiceal carcinoids showed intrinsic tumor positivity whereas the jejunoileal carcinoids did not.


CONCLUSIONS
The finding of IECH with multiple jejunoileal carcinoids suggests that these carcinoids arise from a field effect. The absence of IECH with appendiceal carcinoids as well as their association with subepithelial endocrine cell aggregates and their intimate relationship with Schwann cell processes suggests that appendiceal carcinoids arise from a more discrete unit, the subepithelial neuroendocrine complex.
Moyana
T N
TN
Department of Pathology, University of Saskatchewan, Saskatoon, Canada.
Satkunam
N
N
D000293:Adolescent; D000328:Adult; D000368:Aged; D001063:Appendiceal Neoplasms / Q000737:chemistry / Q000209:etiology* / Q000473:pathology; D002276:Carcinoid Tumor / Q000737:chemistry / Q000209:etiology* / Q000473:pathology; D053379:Chromogranin A; D002864:Chromogranins / Q000032:analysis; D004702:Endocrine Glands / Q000166:cytology; D005260:Female; D006801:Humans; D007078:Ileal Neoplasms / Q000737:chemistry / Q000209:etiology* / Q000473:pathology; D007150:Immunohistochemistry; D007580:Jejunal Neoplasms / Q000737:chemistry / Q000209:etiology* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D012701:Serotonin / Q000032:analysis; D013194:Staining and Labeling
D053379:Chromogranin A; D002864:Chromogranins; D012701:Serotonin