Gastric Fundic Gland Adenocarcinoma: Clinical, Histological and Immunohistochemical Characterization.
Mohammad Raoufi, Anli Chen, Noam Harpaz. Mount Sinai School of Medicine, New York, NY
Background: Gastric fundic gland adenocarcinoma (FGA) is a newly recognized entity reported in the Japanese population. We report the first series of U.S. cases and describe the tumor's clinical, histological and immunohistochemical characteristics.
Design: Three patients were diagnosed with FGA in consultation within a 1-year interval. The clinical records were reviewed and paraffin-embedded tissue was obtained for further study. All lesions underwent immunohistochemical staining for the following: pepsinogen II (Novus Biologicals); sodium channel antigen ACCN5 (Sigma-Aldrich); MUC2, MUC5A/C and MUC6 (Dako); and Dolichos biflorus lectin (DBA, Vector).
Results: The patients, all females between 48-81y of age, underwent upper endoscopy for nonspecific symptoms. None had any history of gastric neoplasia or gastrointestinal polyposis. One was on chronic PPI therapy. Endoscopically, each presented a sessile polyp of 3-8mm in diameter in the gastric body or fundus. Two patients underwent complete endoscopic polypectomy and the 3rd underwent a biopsy followed by surgical wedge resection without lymph nodes. The referring diagnoses were inconclusive, proposing an unusual gastric adenoma or atypical glandular proliferation. Microscopically, each of the tumors comprised anastomosing tubular and cribriform glands arising directly from the deep fundic gland compartment and infiltrating the submucosa. The neoplastic epithelium featured 2 distinct phenotypes, a predominant chief cell-like component, i.e, columnar cells with basophilic cytoplasm and round basal nuclei, and a smaller component of interspersed parietal-like cells, i.e., pyramidal eosinophilic cells with round central nuclei. Nuclear atypia ranged from mild to moderate. Abundant mitotic activity with MIB1 index of 20% was noted in 1 case. In 2 patients the adjacent and overlying mucosa were unremarkable, whereas the 3rd, who was taking PPIs, had superimposed features of a fundic gland polyp with parietal cell hyperplasia. Immunohistochemically, the neoplastic chief cell-like epithelium was positive for MUC6 and pepsinogen II and negative for MUC2 and MUC5AC, whereas the parietal-like cells were positive for ACCN5 and/or DBA. One lesion was negative for chromogranin but variably positive for synaptophysin. All the patients are clinically tumor-free after 3-15m of endoscopic follow-up
Conclusions: FGA is a distinct but as yet poorly recognized type of well-differentiated gastric carcinoma. Although conservative modalities may afford adequate therapy, further experience with this entity may better define its clinical behavior.
Tuesday, March 1, 2011 9:30 AM
Poster Session III # 152, Tuesday Morning