title: Cocoon formation in patients with midgut neuroendocrine tumors: a rare and unrecognized final pathway.
abstract: OBJECTIVE
  Neuroendocrine tumors (NETs) are relatively rare with an indolent nature. As a result, treatment is often delayed and passive. The most commonly recognized disease progression leading to death is from the sequelae of bowel obstruction, ischemia, or liver failure secondary to liver metastasis. We recently recognized a rare cocoon-like formation in patients with metastatic gastroenteropancreatic NETs and hypothesize that this may be a distinct, final pathway for these patients.
  
  
  METHODS
  Ten patients with stage IV gastroenteropancreatic NETs, seen at our center between October 2008 and November 2011, who developed a cocoon were identified. Patient's charts, operative reports, pathology, and tumor markers were reviewed.
  
  
  RESULTS
  No discernable predictors were identified as precursors to this condition. One patient survived 13 months after cocoon diagnosis, and the remaining 9 patients were all deceased within 5 months. Surgical treatment was attempted in 6 patients and was only partially successful in 1 patient who had the earliest stage of cocoon formation (type 1).
  
  
  CONCLUSIONS
  Cocoon-like formations in patients with stage IV gastroenteropancreatic NETs is rare and may be a terminal disease progression that has not been previously recognized. The best treatment option remains unknown. Surgical treatment is not advisable, with the exception of type 1 abdominal cocoons.
authors.affiliation: Department of Surgery, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA. ywang@lsuhsc.edu
authors.forename: Yi-Zarn
authors.initials: YZ
authors.lastname: Wang
authors.forename: Heather
authors.initials: H
authors.lastname: King
authors.forename: Anne
authors.initials: A
authors.lastname: Diebold
mesh_terms: D000328:Adult; D000368:Aged; D018450:Disease Progression; D005260:Female; D006801:Humans; D007414:Intestinal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D018358:Neuroendocrine Tumors / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D010190:Pancreatic Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D013274:Stomach Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D015996:Survival Rate; D013997:Time Factors; D016896:Treatment Outcome