Describe Type I gastric neuroendocrine tumors
Type I tumors represent 70% to 80% of all gastric endocrine tumors.
-associated with hypergastrinemia resulting from autoimmune (corpus-restricted) atrophic gastritis and, therefore, are found more commonly in elderly patients, particularly women, with atrophic gastritis and often are associated with pernicious anemia.
These tumors are small (<1 cm), confined to the oxyntic mucosa, and tend to be multiple and usually co-exist with multifocal ECL cell hyperplasia.
Gastric neuroendocrine tumors tend to be found incidentally, often in patients undergoing EGD as part of an evaluation for anemia.
Describe Type II gastric neuroendocrine tumors
Type II gastric neuroendocrine tumors are associated with hypergastrinemia resulting from a gastrin-secreting tumor. They frequently are detected as part of the work-up for MEN-1 syndrome or for Zollinger–Ellison syndrome. In both instances the tumors are usually small (<1 cm) and show neither infiltrating nor pleomorphic features.
This type of neuroendocrine tumor is the most uncommon, representing only 5% to 8% of gastric neuroendocrine tumors.
Describe Type III gastric neuroendocrine tumors
Type III (sporadic) neuroendocrine tumors are not associated with hypergastrinemia, are generally solitary, arise in otherwise healthy gastric mucosa, and are not accompanied by ECL cell hyperplasia.
These tumors, which represent approximately 20% of all gastric neuroendocrine tumors, usually are detected when they become symptomatic, either secondary to mucosal erosion and blood loss or metastasis. Because these events tend to occur only after the tumors reach a certain size, these tumors are usually larger than 1.5 cm, display infiltrating growth patterns with areas of necrosis, and show various degrees of pleomorphism.
Their proliferation index is high (mitotic count >20 per high-power field or a Ki-67 index > 20%). Type III neuroendocrine tumors have a generally poor prognosis with a mean survival of 28 months
Where do carcinoid tumors arise from?
from neuroendocrine organs (e.g. the endocrine pancreas) and neuroendocrine-differentiated GI epithelia such as G cells in the antrum of the stomach
Where are the majority of carcinoid tumors found?
the majority are found in the GI tract, with more than 40% being found in the small intestine. The tracheobronchial tree and lungs are the next most commonly invovled
What pts typically get carcinoid tumors?
Peak incidence in 60s, but may appear at any age and symptoms are determined by the hormones produced.
How might Type I gastric carcinoid tumors present?
-older pts. presenting with epigastric pain and anemia (If you see someone older than 40 with anemia and abdominal pain, you have to think CANCER. Weight loss and poor appetite increases likelihood)
-Endoscopy showing many (10+) small nodules in the **body and fundus** of the stomach
How would a biopsy of a carcinoid tumor look?
aggregates of neuroendocrine cells consistent with hyperplasia or carcinoid tumors
What is the most important prognostic factor for GI carcinoid tumors?
Describe foregut carcinoid tumors
these are typically found in the stomach, duodenum proximal to the ligament of Treitz, and esophagus, and rarely MET (cured by resection) (This is particularly true for gastric carcinoid tumors that arise in association with atrophic gastritis)
Keep in mind that gastrinomas located in the pancreas and duodenum can arise (ZE syndrome) and are associated with PPI therapy
Describe midgut carcinoid tumors
These often arise in the jejunum and ileum and are often multiple and tend to be aggressive. In these tmors, greater depth of local invasion, increased size, and presence of necrosis and mitoses are associated with poor outcome
Describe hindgut carcinoid tumors
These arising in the appendix and colorectum are mostly found incidentally. Those in the appendix (the most common tumor of the appendix!) are benign, while rectal carcinoids are more likely to produce hormones and manifest with abdominal pain and weight loss and MET
What is autoimmune gastritis?
Accounts for 10% of chronic gastritis cases and is marked by antibodies to and loss of parietal cells (and intrinsic factor) resulting in:
-reduced serum pepsinogen I levels (loss of chief cells)
-antral endocrine cell hyperplasia
-vitamin B12 deficiency
-achlorhydria (acid production decreased but gastrin increased due to lack of feedback, causing antral G cell hyperplasia)
Where does autoimmune gastritis occur?
There is diffuse damage of the oxyntic (Acid-producing) mucosa within the body and fundus, with damage to the antrum and cardia typically absent
What are some sequelae of autoimmune gastritis?
Atrophy, pernicious anemia, adenocarcinoma, carcinoid tumor
What are some associations of autoimmune gastritis?
other autoimmune disease; thyroiditis, DM, graves disease
Describe what is occurring in this biopsy of autoimmune gastritis
Autoimmune gastritis is marked by diffuse atrophy of the oxyntic mucosa of the body and funding, causing it to appear markedly thinned, with loss of rugal folds. Neutrophils may be present, but the main inflammatory infiltrate is composed of lymphocytes, macrophages, and plasma cells
Intestinal metaplasia and Neuroendocrine hyperplasia may also be seen (usually use an immunostain to find)
How would Type I gastric carcinoid tumors be treated most often?
Usually you try to remove the source of gastrin, the antrum, in an antrectomy, and pts. recover
What are your thoughts?
Definitely thinking cancer, and the symptoms are consistent with carcinoid syndrome releasing serotonin/histamine etc.
What additional tests should be ordered for pt 2?
CT scan (CT shows HYPERdense lesions indicating METS from NE tumor; adenocarcinoma METs are HYPOdense)
Urine 5-HIAA and Chromogranin levels
Biopsy of liver lesion
Nuclei may have salt;pepper pattern
Carcinoid EVREYWHERE looks the same (cant tell where its coming from in histology)
What other immunostains would be positive in this tumor?
Chromogranin, synaptophysin, and CD56
What is carcinoid syndrome?
The production of vasoactive substances/serotonin from carcinoid tumors that produce episodes of cutaneous flushing, sweating, bronchospasm, colicky abdominal pain, and diarrhea
Carcinoid syndrome VERY HIGHLY suggests METs. Why?
Because tumors confined to the intestine release their vasoactive substances to be subjected to first-pass like effects in the liver
•Occurs in 10% of patients with carcinoid tumors, typically ileal tumors with liver metastases - bioactive products can be released directly into systemic circulation. Also can be overcome with large tumor burden and hormones secreted into nonportal circulation.
What urine assay is fairly diagnostic for carcinoid syndrome?
High urine 5-hydroxyindole acetic acid (5-HIAA)
What is Zollinger-Ellison Syndrome?
Gastrinoma of pancreatic, duodenual, or peripancreatic soft tissue origin that cause severe peptic ulceration (along with gastric acid hypersecretion, weight loss and diarrhea) that are:
-identical to those found in the general population but unresponsive to therapy
-may be found in the jejunum
How is ZE Syndrome diagnosed?
•Fasting gastrin level >1000 pg/ml with gastric pH below 5
•Secretin stimulation test
Gastrin levels 0, 2, 5, 10, 15 & 20 min after IV Secretin
Increase in gastrin of >200 pg/ml (In these pts secretin will paradoxically INCREASE gastrin levels)
(sensitivity 83%, specificity 100%)
Why do pts with ZE Syndrome have diarrhea?
They have diarrhea because pancreatic enzymes are activated at pH 5+ so hypergastrin levels will not allow them to be activated
How should ZE Syndrome be managed?
Surgical resection is indicated for solitary, non-metastatic disease
All pts should receive high-dose PPIs, and long acting somatostatin analogs have shown to be effective
What are the tx options for metastatic ZE Syndrome?
oStreptozocin/doxorubicin or temozolomide
oResection, Trans-arterial chemo-embolization(TACE), Radiofrequency ablation (RFA), Orthotopic liver transplantation (OLT)