Carcinoid Tumor, Stomach



Carcinoid Tumor, Stomach


Gregory Y. Lauwers, MD





Key Facts


Clinical Issues



  • Gastric carcinoids represent 5% of all gastrointestinal carcinoids


  • Most carcinoids (type 1, 2, and 4) are fundic


  • Type 3 can arise anywhere in gastric mucosa


  • Majority of gastric carcinoids are slowly growing, locally infiltrative, and generally of low-grade malignancy


  • Endoscopic resection advocated for small tumors limited in numbers


  • Antrectomy that removes hypergastrinemic drive advocated for type 1 carcinoid


  • Metastases do not preclude long-term survival


Macroscopic Features



  • Commonly multiple


  • Small, smooth, firm, circumscribed, polypoid elevations of mucosa and submucosa


Microscopic Pathology



  • Small cuboidal cells with round nuclei with evenly dispersed chromatin


  • Solid, trabecular, and ribbon-like arrangement


  • Commonly infiltrate submucosa but seldom deeper


  • High-grade sporadic carcinoid tumor may resemble small cell carcinoma


  • Immunocytochemistry positive for chromogranin-A, synaptophysin, Leu-7 and PGP9.5, and CEA-M


  • Background corpus mucosa of type 1, 2, and 4 carcinoids shows various patterns of ECL-cell hyperplasia







Hematoxylin & eosin shows a distinct invasive carcinoid extending the submucosa. Even at this low power, the insular and trabecular organization can be recognized.






Synaptophysin of the corresponding case confirms the histologic diagnosis and highlights the architecture of the tumor.


TERMINOLOGY


Definitions



  • Neuroendocrine neoplasms arising from enterochromaffin-like (ECL) cells



    • > 0.5 mm in size or invading submucosa


ETIOLOGY/PATHOGENESIS


Autoimmune Gastritis



  • Related to type 1 carcinoid (75% of cases)


  • Gastrin hypersecretion causes hyperplasia and neoplastic transformation of gastric ECL cells


Zollinger-Ellison Syndrome Associated with MEN1



  • Related to type 2 carcinoid (5-10% of cases)


  • Gastrin hypersecretion by gastrin-secreting tumor causes hyperplasia and neoplastic transformation of gastric ECL cells


Sporadic



  • Related to solitary and larger type 3 carcinoids


Defect of Acid Secretion by Parietal Cells



  • Related to type 4 carcinoids


  • Hypergastrinemia is secondary to achlorhydria


CLINICAL ISSUES


Epidemiology



  • Incidence



    • 5% of all gastrointestinal carcinoids


    • 1% of all gastric tumors


  • Age



    • Middle-aged adults


  • Gender



    • Type 1 and 2 tumors more common in women


    • Men overrepresented in type 3 tumors


Site



  • Most carcinoids (type 1, 2, and 4) are fundic


  • Type 3 carcinoids can arise anywhere in gastric mucosa


Presentation



  • 50% of patients with type 1 carcinoids have pernicious anemia


  • Patients with type 2 carcinoids will present with symptoms of Zollinger-Ellison and MEN1


  • Sporadic type 3 tumors are larger and may produce symptoms suggestive of gastric carcinoma



    • Hemorrhage, obstruction, or metastasis


  • Peptide hormone hypersecretion-related symptoms are uncommon



    • Atypical carcinoid syndrome has been reported


    • Cushing syndrome from ectopic corticotrophin secretion has been reported


Endoscopic Findings



  • Type 1, 2, and 4 carcinoids present as polypoid, yellowish nodules



    • Central erythematous depression


    • Multiple and limited to gastric corpus


  • Sporadic carcinoids tend to be solitary and larger


Natural History



  • Majority of gastric carcinoids are generally of low-grade malignancy



    • Slow growing and locally infiltrative



      • Tumors < 1 cm in diameter and confined to mucosa and submucosa rarely metastasize


      • Multiple type 1, 2, and 4 carcinoids are usually small (< 1 cm)


      • Type 1 carcinoids can regress with time


  • Large (usually type 3) tumors with vascular or muscularis propria invasion can spread to lymph nodes and liver


  • Rare functioning tumors that lead to clinical hypersecretion syndrome are always malignant



Treatment



  • Local excision or endoscopic resection



    • Advocated for small tumors up to 5 in number



      • Extirpation of new lesions as they arise


  • Antrectomy



    • Removal of antral G cells (which provide hypergastrinemic drive) advocated for type 1 carcinoid


    • Numerous or large carcinoid tumors, which cannot be managed endoscopically


  • Aggressive resection



    • Large and invasive sporadic type 3 carcinoid


    • Numerous small lesions that cannot be managed conservatively


Prognosis

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Jul 6, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Carcinoid Tumor, Stomach

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