RT Book, Section
A1 Jensen, Robert T.
A2 Jameson, J. Larry
SR Print(0)
ID 1141276172
T1 Endocrine Tumors of the Gastrointestinal Tract and Pancreas
T2 Harrison's Endocrinology, 4e
YR 2017
FD 2017
PB McGraw-Hill Education
PP New York, NY
SN 9781259835728
LK accessbiomedicalscience.mhmedical.com/content.aspx?aid=1141276172
RD 2024/04/20
AB Gastrointestinal  (GI)  neuroendocrine  tumors  (NETs)  are  tumors  derived  from  the  diffuse  neuroendocrine  system  of  the  GI  tract;  that  system  is  composed  of  amine-  and  acid-producing  cells  with  different  hormonal  profiles,  depending  on  the  site  of  origin.  The  tumors  historically  are  divided  into  GI-NETs  (in  the  GI  tract)  (also  frequently  called  carcinoid  tumors)  and  pancreatic  neuroendocrine  tumors  (pNETs),  although  newer  pathologic  classifications  have  proposed  that  they  all  be  classified  as  GI-NETs.  The  term  GI-NET  has  been  proposed  to  replace  the  term  carcinoid;  however,  the  term  carcinoid  is  widely  used,  and  many  are  not  familiar  with  this  change.  Accordingly,  this  chapter  will  use  the  term  GI-NETs  (carcinoids).  These  tumors  originally  were  classified  as  APUDomas  (for  amine  precursor  uptake  and  decarboxylation),  as  were  pheochromocytomas,  melanomas,  and  medullary  thyroid  carcinomas,  because  they  share  certain  cytochemical  features  as  well  as  various  pathologic,  biologic,  and  molecular  features  (Table  28-1).  It  was  originally  proposed  that  APUDomas  had  a  similar  embryonic  origin  from  neural  crest  cells,  but  it  is  now  known  the  peptide-secreting  cells  are  not  of  neuroectodermal  origin.  Nevertheless,  the  concept  of  APUDomas  is  useful  because  these  tumors  have  important  similarities  as  well  as  some  differences  (Table  28-1).  In  this  section,  the  areas  of  similarity  between  pNETs  and  GI-NETs  (carcinoids)  will  be  discussed  together,  and  areas  in  which  there  are  important  differences  will  be  discussed  separately.