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CARCINOID SYNDROME AND ISLET CELL TUMORS

CARCINOID SYNDROME

The appendix is the commonest site of carcinoid syndrome in the gastrointestinal tract.

  • These tumors are slow growing
  • Other sites that could be involved are :, small intestine, lung and rectum.
  • Lesions usually single but could be multiple
  • Clinical symptoms produced by elevated 5-HIAA level.

Signs and Symptoms
  • flushing
  • diarrhea
  • heart disease e.g. tricuspid valve stenosis
  • spasms of the airways (bronchconstriction)
  • intestinal obstruction
  • fibrosis of the mesentery

Diagnostic Tests

  1. biopsy
  2. blood and urinary level of 5-HIAA (hydroxyindoleacetic acid)

Treatment

  • for resectable tumors prognosis is good and patients may be free of disease 20 years and more after resection
  • for tumors less than 1cm. In the appendix, simple excision is adequate
  • for tumors greater than 2cm, right hemicolectomy needs to be done.
  • In patients with lymph node involvement , progosis is not as good as the compleyely resectable lesions
  • Even in patients with metastasis, patients may still live for 3 to 5 years

ISLET CELL TUMORS

  • usually pose a diagnostic difficulty
  • it could occur sporadically or as familial disease
  • the familial disease is inherited in an autosomal dominant fashion
  • the synonym is multiple endocrine neoplasia (MEN)
  • MEN type 1:consists of tumors of the pituitary gland, parathyroid gland and tumors of the islet cells of the pancreas
  • MEN type 2: consists of phaeochromocytomas, parathyroid tumors and medullary carcinomas of the thyroid.
  • If the tumors do not produce active hormones, they are usually asymptomatic
  • The symptoms produced depend on the type of hormone produced


    a. VIPomas: these tumors produce vasoactive intestinal peptide producing severe diarrhea

    it is called Verner-Morrison syndrome

  • also causes hypokalemia and achlorhydia
  • occurs more in females
  • causes significant weight loss
  • these tumors could arise from the pancreas, intestinal carcinoids , pheochromocytomas and ganglionneuroblastoma
  • diagnosis is made by immunohistochemical stains for HPP, glucagon,
  • treatment consists of replacing the lost fluid and electrolytes
  • Octreotide plus glucocorticoid
  • For non-metastatic diseases, resection may curative in about one-third of patients


GRFomas

  • these tumors produce growth hormone releasing factor
  • common sites of origin include the lung and pancreas
  • ommoner in females
  • patients present with acromegalic features
  • surgical resection is for localized tumors
  • resolution of the symptoms is expected with resection


Gastrinomas

  • there is excessive production of gastrin with increased production of gastric acid producing gastric ulcer
  • they are usually metastatic at presentation
  • treatment consists of surgical resection and H2- blockers

Glucagonomas

  • there is increased production of glucagon which is a hormone that leads to increased glucose formation
  • glucose intolerance is a mode of presentation
  • patients usually present with migratory, necrolytic rash
  • they are usually metastatic at presentation


Insulinomas

  • these tumors are usually benign
  • there is increased production of insulin hence producing hypoglycemia ( low blood sugar)
  • symptoms include but are not limited to sweating, fainting attacks, rapid heart beat (palpitation)
  • surgical resection is usually curative


Other treatment modalities for Islet cell tumors

  • surgical resection for benign or non-metastatic tumors
  • radiation therapy to palliate pain at different sites
  • somatostatin analogues ( please note Sandostatin may cause gallstones)
  • alpha interferon
  • chemotherapy consisting of streptozocin and adriamycin is the standard treatment for islet cell tumors
  • whereas cisplatin and etoposide combination is the treatment of choice for neuroendocrine tumors
  • hepatic artery embolization
  • cryosurgery