Prevalence of CD99 protein expression in pancreatic endocrine tumours (PETs).
OBJECTIVE
To determine the prevalence of CD99 expression in pancreatic endocrine tumours (PETs). We evaluated CD99 expression and analysed Ki67 labelling by immunohistochemistry in PETs.


RESULTS
Thirty-eight PETs from 33 patients were analysed. CD99 immunoreactivity was consistently observed in normal islets of the pancreas, regardless of the cell type. Tumours comprising more than 30% CD99+ cells were defined as positively immunoreactive for CD99. CD99 expression was observed in 20 of the 38 PETs examined, but not in any of the pancreatic tumours of other histological subtypes (10 ductal adenocarcinomas, five intraductal papillary-mucinous tumours, and two acinar cell tumours). Loss of CD99 expression was related to markers of worse prognosis for PET, including gross local invasion, metastasis to the lymph nodes or other organs, lymphatic or blood vessel invasion, and neuroendocrine carcinoma (NEC). Thus, CD99 expression may have an efficiency comparable to that of high Ki67 labelling index (5% or more) for prognostication.


CONCLUSIONS
CD99 expression was observed frequently and exclusively in PETs, and loss of CD99 expression in PETs was found to be associated with ominous prognostic indicators.
Department of Human Pathology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan. akiteru@m.u-tokyo.ac.jp
A
A
Goto
T
T
Niki
Y
Y
Terado
J
J
Fukushima
M
M
Fukayama
D000071443:12E7 Antigen; D000328:Adult; D015703:Antigens, CD / Q000096:biosynthesis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D015815:Cell Adhesion Molecules / Q000096:biosynthesis*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000378:metabolism; D008207:Lymphatic Metastasis / Q000473:pathology; D008297:Male; D008875:Middle Aged; D018761:Multiple Endocrine Neoplasia Type 1 / Q000378:metabolism / Q000473:pathology; D009361:Neoplasm Invasiveness; D009375:Neoplasms, Glandular and Epithelial / Q000378:metabolism / Q000473:pathology*; D018358:Neuroendocrine Tumors / Q000378:metabolism / Q000473:pathology; D010190:Pancreatic Neoplasms / Q000378:metabolism / Q000473:pathology*; D015995:Prevalence; D011379:Prognosis
D000071443:12E7 Antigen; D015703:Antigens, CD; D014408:Biomarkers, Tumor; C061828:CD99 protein, human; D015815:Cell Adhesion Molecules; D019394:Ki-67 Antigen