Hyperplastic Polyp of the Stomach

Background

These are the most common epithelial polyps of the stomach and are found throughout the stomach, ranging in size from a few millimeters to centimeters. Hyperplastic polyps have been reported in association with various types of chronic gastritis, particularly autoimmune gastritis, Helicobacter pylori gastritis, and the postantrectomy stomach.

OUTLINE

Disease Associations

Pathogenesis

Laboratory/Radiologic/
Other Diagnostic Testing

Gross Appearance and Clinical Variants

Histopathological Features and Variants

Special Stains/
Immunohistochemistry/
Electron Microscopy

Differential Diagnosis

Prognosis

Treatment

Commonly Used Terms

Internet Links

DISEASE ASSOCIATIONS CHARACTERIZATION

PROTON PUMP THERAPY

Proton pump inhibitor-associated gastric polyps: a retrospective analysis of their frequency, and endoscopic, histologic, and ultrastructural characteristics.

Choudhry U, Boyce HW Jr, Coppola D.

Center for Swallowing Disorders, Division of Digestive Diseases, University of South Florida College of Medicine, Tampa 33612-9497, USA.

Am J Clin Pathol 1998 Nov;110(5):615-21 Abstract quote

Since 1992 there have been reports of proton pump inhibitors being associated with fundic gland-type gastric polyps. Endoscopic and histologic characteristics and natural history of these polyps have not been clearly defined.

We performed a retrospective study of patients on long-term treatment with proton pump inhibitors who developed gastric polyps. Gastric polyps developed in 17 (10 males and 7 females, 7.3%) of the 231 patients who underwent 2 or more upper endoscopies for complicated gastroesophageal reflux disease and who were receiving long-term treatment with proton pump inhibitors.

The mean interval of proton pump inhibitor use after which an endoscopy revealed gastric polyps was 32.5 months. In 1 patient, discontinuation of treatment resulted in disappearance of the polyps within 3 months. The polyps recurred 4 months after the treatment was restarted. Endoscopy established that typical polyps were generally small (<1 cm), sessile, multiple, and whitish pink with a mottled partially translucent surface. The polyps were most often present in the proximal/midgastric body. Of the 15 polyps removed endoscopically, 9 were of the fundic gland type, 4 were of the hyperplastic type, and 2 were of the inflammatory type. Eight of 9 polyps with typical endoscopic appearance were of the fundic gland type. None of the polyps contained dysplasia or carcinoma.

Long-term use of proton pump inhibitors may be associated with the presence of small gastric fundic gland polyps and hyperplastic polyps. A prospective study is required to establish their incidence, natural history, and clinical significance.

XANTHELASMA

Gastric xanthelasma in hyperplastic gastric polyposis.

Lin PY, Brown DB, Deppisch LM.

Department of Pathology, Western Reserve Care System, North Side Hospital, Youngstown, OH 44501.

Arch Pathol Lab Med 1989 Apr;113(4):428-30 Abstract quote

Hyperplastic polyps of the stomach are uncommon, while xanthelasma of the gastric mucosa has a variable reported frequency. The frequency of both lesions appear increased in association with chronic gastritis and previous gastrointestinal anastomosis.

The present article consists of a case report that documents for the first time (to our knowledge) the coexistence of these two lesions in a patient with a history of erosive gastritis.

PATHOGENESIS CHARACTERIZATION

MALIGNANT TRANSFORMATION

p53, but not c-Ki-ras, mutation and down-regulation of p21WAF1/CIP1 and cyclin D1 are associated with malignant transformation in gastric hyperplastic polyps.

Murakami K, Mitomi H, Yamashita K, Tanabe S, Saigenji K, Okayasu I.

Departments of Internal Medicine, School of Medicine, Kitasato University, Sagamihara, Japan.

Am J Clin Pathol 2001 Feb;115(2):224-34 Abstract quote

To investigate tumorigenesis in the gastric hyperplastic polyp (HP), we evaluated 19 HPs with and 50 HPs without dysplasia (including carcinoma in situ), as compared with normal mucosa and fundic gland polyps.

Helicobacter pylori density was highest in HPs without dysplasia. Apoptotic activity and Ki-67 and p53 expression also were higher in dysplasia in HPs than in normal mucosa, fundic gland polyps, or HPs themselves. The p21WAF1/CIP1 and cyclin D1 levels, in contrast, were highest in HPs. In HPs without dysplasia, size was correlated positively with the degree of stromal inflammation and with p53 and cyclin D1 expression. p53 and c-Ki-ras mutations were detected in 41% (8/19) and 5% (1/19) of dysplasia (including carcinoma in situ) in HPs.

Our results demonstrate that the HP enlarges with enhanced cell turnover and overexpression of p53, p21WAF1/CIP1, and cyclin D1, associated with H pylori-related inflammation, and that p53 but not c-Ki-ras mutations may have an important role in dysplastic change in HPs.

Malignant transformation of gastric hyperplastic polyps: Alteration of phenotypes, proliferative activity, and p53 expression.

Yao T, Kajiwara M, Kuroiwa S, Iwashita A, Oya M, Kabashima A, Tsuneyoshi M.

Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan and the Department of Pathology, Chikushi Hospital, Fukuoka University, Fukuoka, Japan.
Hum Pathol 2002 Oct;33(10):1016-22 Abstract quote
The aim of this study was to clarify the mechanism of malignant transformation of gastric hyperplastic polyps, focusing on phenotypic expression, cell proliferation, and p53 overexpression.

Twenty-two lesions of gastric hyperplastic polyps with neoplastic foci were selected for this study. The phenotypes were divided into 3 types (G, gastric; incomp I, incomplete intestinal; and comp I, complete intestinal), according to immunohistochemical stains (human gastric mucin [HGM], MUC2, and CD10). The cell proliferative activity by Ki-67 and overexpression of p53 protein were also examined. Eleven of these lesions contained carcinoma components (CA, category 5 by the Vienna classification), 6 of which were accompanied by low-grade dysplasia (LGD, category 3) and 4 of which were accompanied by high-grade dysplasia (HGD, category 4). Another 2 were composed only of HGD, and the remaining 9 were composed of both LGD and HGD components. As a result, 15 LGD, 15 HGD, and 11 CA components were recognized. The 15 LGD components were classified as 1 G type and 14 incomp I type. All hyperplastic components expressed HGM, 5 (22.7%) of which were accompanied by focal intestinal metaplasia demonstrated by MUC2 expression, whereas intestinalization frequently occurred in neoplastic components (93% of LGD, 53% of HGD, and 64% of CA components). The labeling index was 22.2% in hyperplastic, 42.2% in LGD, 55.7% in HGD, and 53.9% in CA components. p53 protein overexpression was recognized in none of hyperplastic, in 40% of the LGD, in 60% of the HGD, and in 45% of the CA components.

These results suggest the importance of the dysplasia-carcinoma sequence in malignant transformation of hyperplastic polyps. Interestingly, intestinalization frequently occurs during neoplastic transformation, although it is not common in the surrounding hyperplastic components.

HISTOLOGICAL TYPES CHARACTERIZATION

General
Hyperplastic, elongated, or dilated foveolae that are admixed with variable amounts of inflamed stroma

Lining of the foveolae is composed of mature gastric mucous cells with abundant cytoplasm, except in areas of surface erosions, where nuclear enlargement and depletion of cytoplasmic mucin may lend a markedly regenerative appearance

Gastric Polyps: Classification and Meaning

Susan C. Abraham, MD

From the Division of Gastrointestinal/Liver Pathology, Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD.

Pathol Case Rev 2002;7:2-11 Abstract quote

Gastric polyps encompass a wide variety of lesions that most commonly arise from the gastric epithelium. This review focuses on the histologic features, significance, and differential diagnosis of the two most common epithelial polyps: hyperplastic polyps and fundic gland polyps.

Hyperplastic polyps are characterized by prominent foveolar hyperplasia, tortuosity, and edema and inflammation of the intervening lamina propria. They are associated with abnormalities of the background gastric mucosa, particularly chronic atrophic gastritis of autoimmune or environmental type. Although they uncommonly undergo neoplastic progression (dysplasia or adenocarcinoma), they denote an increased risk of neoplasia in the surrounding abnormal gastric mucosa. Hyperplastic polyps overlap in their histologic appearance with hamartomas (e.g., juvenile polyps, Peutz-Jeghers polyps, Cowden�s disease) and with more generalized hyperplastic or inflammatory conditions (e.g., Menetrier�s disease).

Fundic gland polyps can be sporadic or associated with familial adenomatous polyposis (FAP). FAP-associated polyps occur at earlier ages (including children) and are more frequently multiple. Both sporadic and FAP-associated fundic gland polyps are characterized by ectatic glands lined by attenuated parietal cells, chief cells, and mucus neck cells. The surface epithelium is dysplastic in 25% of FAP-associated fundic gland polyps but only rarely in sporadic polyps. Despite this, the risk of gastric adenocarcinoma does not appear to be significantly increased among Western patients with FAP.

VARIANTS

DYPLASIA Prevalence of true dysplasia arising in hyperplastic polyps is debated, but reported rates have varied from 1.9% to 19%

GASTRITIS

Hyperplastic Polyps of the Stomach Associations With Histologic Patterns of Gastritis and Gastric Atrophy

Susan C. Abraham, etal.

Am J Surg Pathol 2001;25:500-507 Abstract quote

Hyperplastic polyps are common gastric lesions characterized by hyperplastic foveolae with variable amounts of inflamed stroma. Their pathogenesis is unknown, but they have been reported to occur in association with various forms of chronic gastritis, particularly autoimmune gastritis and Helicobacter pylori gastritis. Comprehensive histologic evaluation of the background mucosal pathology in patients with hyperplastic polyps has not been previously performed.

We studied 160 patients with gastric hyperplastic polyps and characterized endoscopic and histologic features of the polyps (i.e., location, multiplicity, and presence of dysplasia and adenocarcinoma) and the background gastric mucosa (i.e., intestinal metaplasia, dysplasia, carcinoma, and presence and classification of gastritis).

Hyperplastic polyps were most common in the antrum (60%) and were multiple in 20% of patients. Focal intestinal metaplasia of the polyp was present in 16% and dysplasia in 4% of patients. Only one patient (0.6%) had adenocarcinoma within the polyp. Evaluation of the surrounding gastric mucosa showed at least focal intestinal metaplasia in 37% of patients, adenoma or low-grade flat epithelial dysplasia in 2%, and synchronous or metachronous adenocarcinoma in 6%. Eighty-five percent of patients had inflammatory mucosal pathology, most commonly active chronic H. pylori gastritis (25%), reactive or chemical gastropathy (21%), and metaplastic atrophic gastritis of the autoimmune (12%) or environmental (8%) type.

These results indicate a strong association between various forms of gastritis and the development of hyperplastic polyps and further emphasize the importance of biopsy of the nonpolypoid gastric mucosa during endoscopic examination.

PROGNOSIS AND TREATMENT CHARACTERIZATION

PROGNOSIS

GENERAL

Histologic types and surveillance of gastric polyps: a seven year clinico-pathological study.

Papa A, Cammarota G, Tursi A, Montalto M, Cuoco L, Certo M, Fedeli G, Gasbarrini G.

Department of Internal Medicine, Catholic University of Rome, Italy.

Hepatogastroenterology 1998 Mar-Apr;45(20):579-82 Abstract quote

BACKGROUND/AIMS: This is a seven-year prospective study based on all gastroscopic examinations of our patient population in order to study gastric polyps.

METHODOLOGY: One hundred and twenty-one polyps, removed from 96 patients were analysed. All polyps, after endoscopic polypectomy, were classified according to their histotype. The follow-up was carried out in 49 patients for a mean time of 40 months.

RESULTS: Polypoid lesions were more frequent in females (57.3%) and they were preferentially located in antrum (60.3%). Hyperplastic and inflammatory polyps were 55.4% and 28.9%, respectively, while adenomatous lesions were 9.9%. Four fundic gland polyps, 1 carcinoid, 1 type I early gastric cancer and 1 pancreatic heterotopia were also found. During the follow-up no malignant lesion was encountered. On the other hand 25 benign polyps were found in 19 patients.

CONCLUSIONS: Our experience confirms that there is a close relationship between the size of the polyps and the neoplastic change. In fact, in our series all polyps were smaller than 2 cm and only one malignancy was found (an early gastric cancer). None of adenomatous polyps was associated with gastric adenocarcinoma. Our data also indicates that when a polypectomy is carried out for small polyps (smaller than 2 cm.) a strict follow-up is necessary for the neoplastic polyps only.

MALIGNANT TRANSFORMATION Cases of adenocarcinoma developing in association with hyperplastic polyps have occasionally been reported ranging from 0% to 13.5%

Histoclinical long-standing follow-up study of hyperplastic polyps of the stomach.

Kamiya T, Morishita T, Asakura H, Munakata Y, Miura S, Tsuchiya M.
Am J Gastroenterol 1981 Apr;75(4):275-81 Abstract quote
In a series of 2,013 gastric polyps in 1,201 patients, morphological and histopathological studies have been performed. Ninety-three hyperplastic polyps in 56 patients have been followed-up endoscopically and histopathologically for five to 12 years. The incidence of detection of gastric polyps has increased: 1.4% in 1967 to 8.7% in 1979 year by year. Thirty patients (54%) among the 56 showed changes in number, size or shape of polyps during follow-up. Twenty patients (37%) revealed numerical changes (increase in 16 patients, reversion in three patients and vanishing in two patients). Twenty-eight polyps (30%) showed morphological changes, six of them showed continuous enlargement, 18 lesions repeated enlargement, stationary or reduction stages, three lesions were reversed and two polyps disappeared.

Histopathologically, three lesions showed transformation from the hyperplastic type to adenoma while demonstrating morphological enlargement. Two of these showed increase in cellular atypia, from the hyperplastic type through adenoma with severe atypia and finally to carcinoma in the polypectomy specimens.

From this study, it was concluded that although hyperplastic polyps show changes in size, shape or number with passage of time, malignant changes occur in only a few cases.

TREATMENT Removal

Henry JB. Clinical Diagnosis and Management by Laboratory Methods. Twentieth Edition. WB Saunders. 2001.
Rosai J. Ackerman's Surgical Pathology. Ninth Edition. Mosby 2004.
Sternberg S. Diagnostic Surgical Pathology. Fourth Edition. Lipincott Williams and Wilkins 2004.
Robbins Pathologic Basis of Disease. Seventh Edition. WB Saunders 2005.
DeMay RM. The Art and Science of Cytopathology. Volume 1 and 2. ASCP Press. 1996.
Weedon D. Weedon's Skin Pathology Second Edition. Churchill Livingstone. 2002
Fitzpatrick's Dermatology in General Medicine. 5th Edition. McGraw-Hill. 1999.
Weiss SW and Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors. Fourth Edition. Mosby 2001.

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Last Updated 11/7/2002

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PATHOGENESIS	CHARACTERIZATION
MALIGNANT TRANSFORMATION
p53, but not c-Ki-ras, mutation and down-regulation of p21WAF1/CIP1 and cyclin D1 are associated with malignant transformation in gastric hyperplastic polyps. Murakami K, Mitomi H, Yamashita K, Tanabe S, Saigenji K, Okayasu I. Departments of Internal Medicine, School of Medicine, Kitasato University, Sagamihara, Japan.	Am J Clin Pathol 2001 Feb;115(2):224-34 Abstract quote To investigate tumorigenesis in the gastric hyperplastic polyp (HP), we evaluated 19 HPs with and 50 HPs without dysplasia (including carcinoma in situ), as compared with normal mucosa and fundic gland polyps. Helicobacter pylori density was highest in HPs without dysplasia. Apoptotic activity and Ki-67 and p53 expression also were higher in dysplasia in HPs than in normal mucosa, fundic gland polyps, or HPs themselves. The p21WAF1/CIP1 and cyclin D1 levels, in contrast, were highest in HPs. In HPs without dysplasia, size was correlated positively with the degree of stromal inflammation and with p53 and cyclin D1 expression. p53 and c-Ki-ras mutations were detected in 41% (8/19) and 5% (1/19) of dysplasia (including carcinoma in situ) in HPs. Our results demonstrate that the HP enlarges with enhanced cell turnover and overexpression of p53, p21WAF1/CIP1, and cyclin D1, associated with H pylori-related inflammation, and that p53 but not c-Ki-ras mutations may have an important role in dysplastic change in HPs.
Malignant transformation of gastric hyperplastic polyps: Alteration of phenotypes, proliferative activity, and p53 expression. Yao T, Kajiwara M, Kuroiwa S, Iwashita A, Oya M, Kabashima A, Tsuneyoshi M. Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan and the Department of Pathology, Chikushi Hospital, Fukuoka University, Fukuoka, Japan.	Hum Pathol 2002 Oct;33(10):1016-22 Abstract quote The aim of this study was to clarify the mechanism of malignant transformation of gastric hyperplastic polyps, focusing on phenotypic expression, cell proliferation, and p53 overexpression. Twenty-two lesions of gastric hyperplastic polyps with neoplastic foci were selected for this study. The phenotypes were divided into 3 types (G, gastric; incomp I, incomplete intestinal; and comp I, complete intestinal), according to immunohistochemical stains (human gastric mucin [HGM], MUC2, and CD10). The cell proliferative activity by Ki-67 and overexpression of p53 protein were also examined. Eleven of these lesions contained carcinoma components (CA, category 5 by the Vienna classification), 6 of which were accompanied by low-grade dysplasia (LGD, category 3) and 4 of which were accompanied by high-grade dysplasia (HGD, category 4). Another 2 were composed only of HGD, and the remaining 9 were composed of both LGD and HGD components. As a result, 15 LGD, 15 HGD, and 11 CA components were recognized. The 15 LGD components were classified as 1 G type and 14 incomp I type. All hyperplastic components expressed HGM, 5 (22.7%) of which were accompanied by focal intestinal metaplasia demonstrated by MUC2 expression, whereas intestinalization frequently occurred in neoplastic components (93% of LGD, 53% of HGD, and 64% of CA components). The labeling index was 22.2% in hyperplastic, 42.2% in LGD, 55.7% in HGD, and 53.9% in CA components. p53 protein overexpression was recognized in none of hyperplastic, in 40% of the LGD, in 60% of the HGD, and in 45% of the CA components. These results suggest the importance of the dysplasia-carcinoma sequence in malignant transformation of hyperplastic polyps. Interestingly, intestinalization frequently occurs during neoplastic transformation, although it is not common in the surrounding hyperplastic components.

Disease Associations
Pathogenesis
Laboratory/Radiologic/ Other Diagnostic Testing
Gross Appearance and Clinical Variants
Histopathological Features and Variants
Special Stains/ Immunohistochemistry/ Electron Microscopy
Differential Diagnosis
Prognosis
Treatment
Commonly Used Terms
Internet Links

DISEASE ASSOCIATIONS	CHARACTERIZATION
PROTON PUMP THERAPY
Proton pump inhibitor-associated gastric polyps: a retrospective analysis of their frequency, and endoscopic, histologic, and ultrastructural characteristics. Choudhry U, Boyce HW Jr, Coppola D. Center for Swallowing Disorders, Division of Digestive Diseases, University of South Florida College of Medicine, Tampa 33612-9497, USA.	Am J Clin Pathol 1998 Nov;110(5):615-21 Abstract quote Since 1992 there have been reports of proton pump inhibitors being associated with fundic gland-type gastric polyps. Endoscopic and histologic characteristics and natural history of these polyps have not been clearly defined. We performed a retrospective study of patients on long-term treatment with proton pump inhibitors who developed gastric polyps. Gastric polyps developed in 17 (10 males and 7 females, 7.3%) of the 231 patients who underwent 2 or more upper endoscopies for complicated gastroesophageal reflux disease and who were receiving long-term treatment with proton pump inhibitors. The mean interval of proton pump inhibitor use after which an endoscopy revealed gastric polyps was 32.5 months. In 1 patient, discontinuation of treatment resulted in disappearance of the polyps within 3 months. The polyps recurred 4 months after the treatment was restarted. Endoscopy established that typical polyps were generally small (<1 cm), sessile, multiple, and whitish pink with a mottled partially translucent surface. The polyps were most often present in the proximal/midgastric body. Of the 15 polyps removed endoscopically, 9 were of the fundic gland type, 4 were of the hyperplastic type, and 2 were of the inflammatory type. Eight of 9 polyps with typical endoscopic appearance were of the fundic gland type. None of the polyps contained dysplasia or carcinoma. Long-term use of proton pump inhibitors may be associated with the presence of small gastric fundic gland polyps and hyperplastic polyps. A prospective study is required to establish their incidence, natural history, and clinical significance.
XANTHELASMA
Gastric xanthelasma in hyperplastic gastric polyposis. Lin PY, Brown DB, Deppisch LM. Department of Pathology, Western Reserve Care System, North Side Hospital, Youngstown, OH 44501.	Arch Pathol Lab Med 1989 Apr;113(4):428-30 Abstract quote Hyperplastic polyps of the stomach are uncommon, while xanthelasma of the gastric mucosa has a variable reported frequency. The frequency of both lesions appear increased in association with chronic gastritis and previous gastrointestinal anastomosis. The present article consists of a case report that documents for the first time (to our knowledge) the coexistence of these two lesions in a patient with a history of erosive gastritis.

HISTOLOGICAL TYPES	CHARACTERIZATION
General	Hyperplastic, elongated, or dilated foveolae that are admixed with variable amounts of inflamed stroma Lining of the foveolae is composed of mature gastric mucous cells with abundant cytoplasm, except in areas of surface erosions, where nuclear enlargement and depletion of cytoplasmic mucin may lend a markedly regenerative appearance
Gastric Polyps: Classification and Meaning Susan C. Abraham, MD From the Division of Gastrointestinal/Liver Pathology, Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD.	Pathol Case Rev 2002;7:2-11 Abstract quote Gastric polyps encompass a wide variety of lesions that most commonly arise from the gastric epithelium. This review focuses on the histologic features, significance, and differential diagnosis of the two most common epithelial polyps: hyperplastic polyps and fundic gland polyps. Hyperplastic polyps are characterized by prominent foveolar hyperplasia, tortuosity, and edema and inflammation of the intervening lamina propria. They are associated with abnormalities of the background gastric mucosa, particularly chronic atrophic gastritis of autoimmune or environmental type. Although they uncommonly undergo neoplastic progression (dysplasia or adenocarcinoma), they denote an increased risk of neoplasia in the surrounding abnormal gastric mucosa. Hyperplastic polyps overlap in their histologic appearance with hamartomas (e.g., juvenile polyps, Peutz-Jeghers polyps, Cowden�s disease) and with more generalized hyperplastic or inflammatory conditions (e.g., Menetrier�s disease). Fundic gland polyps can be sporadic or associated with familial adenomatous polyposis (FAP). FAP-associated polyps occur at earlier ages (including children) and are more frequently multiple. Both sporadic and FAP-associated fundic gland polyps are characterized by ectatic glands lined by attenuated parietal cells, chief cells, and mucus neck cells. The surface epithelium is dysplastic in 25% of FAP-associated fundic gland polyps but only rarely in sporadic polyps. Despite this, the risk of gastric adenocarcinoma does not appear to be significantly increased among Western patients with FAP.
VARIANTS
DYPLASIA	Prevalence of true dysplasia arising in hyperplastic polyps is debated, but reported rates have varied from 1.9% to 19%
GASTRITIS
Hyperplastic Polyps of the Stomach Associations With Histologic Patterns of Gastritis and Gastric Atrophy Susan C. Abraham, etal.	Am J Surg Pathol 2001;25:500-507 Abstract quote Hyperplastic polyps are common gastric lesions characterized by hyperplastic foveolae with variable amounts of inflamed stroma. Their pathogenesis is unknown, but they have been reported to occur in association with various forms of chronic gastritis, particularly autoimmune gastritis and Helicobacter pylori gastritis. Comprehensive histologic evaluation of the background mucosal pathology in patients with hyperplastic polyps has not been previously performed. We studied 160 patients with gastric hyperplastic polyps and characterized endoscopic and histologic features of the polyps (i.e., location, multiplicity, and presence of dysplasia and adenocarcinoma) and the background gastric mucosa (i.e., intestinal metaplasia, dysplasia, carcinoma, and presence and classification of gastritis). Hyperplastic polyps were most common in the antrum (60%) and were multiple in 20% of patients. Focal intestinal metaplasia of the polyp was present in 16% and dysplasia in 4% of patients. Only one patient (0.6%) had adenocarcinoma within the polyp. Evaluation of the surrounding gastric mucosa showed at least focal intestinal metaplasia in 37% of patients, adenoma or low-grade flat epithelial dysplasia in 2%, and synchronous or metachronous adenocarcinoma in 6%. Eighty-five percent of patients had inflammatory mucosal pathology, most commonly active chronic H. pylori gastritis (25%), reactive or chemical gastropathy (21%), and metaplastic atrophic gastritis of the autoimmune (12%) or environmental (8%) type. These results indicate a strong association between various forms of gastritis and the development of hyperplastic polyps and further emphasize the importance of biopsy of the nonpolypoid gastric mucosa during endoscopic examination.

PROGNOSIS AND TREATMENT	CHARACTERIZATION
PROGNOSIS
GENERAL
Histologic types and surveillance of gastric polyps: a seven year clinico-pathological study. Papa A, Cammarota G, Tursi A, Montalto M, Cuoco L, Certo M, Fedeli G, Gasbarrini G. Department of Internal Medicine, Catholic University of Rome, Italy.	Hepatogastroenterology 1998 Mar-Apr;45(20):579-82 Abstract quote BACKGROUND/AIMS: This is a seven-year prospective study based on all gastroscopic examinations of our patient population in order to study gastric polyps. METHODOLOGY: One hundred and twenty-one polyps, removed from 96 patients were analysed. All polyps, after endoscopic polypectomy, were classified according to their histotype. The follow-up was carried out in 49 patients for a mean time of 40 months. RESULTS: Polypoid lesions were more frequent in females (57.3%) and they were preferentially located in antrum (60.3%). Hyperplastic and inflammatory polyps were 55.4% and 28.9%, respectively, while adenomatous lesions were 9.9%. Four fundic gland polyps, 1 carcinoid, 1 type I early gastric cancer and 1 pancreatic heterotopia were also found. During the follow-up no malignant lesion was encountered. On the other hand 25 benign polyps were found in 19 patients. CONCLUSIONS: Our experience confirms that there is a close relationship between the size of the polyps and the neoplastic change. In fact, in our series all polyps were smaller than 2 cm and only one malignancy was found (an early gastric cancer). None of adenomatous polyps was associated with gastric adenocarcinoma. Our data also indicates that when a polypectomy is carried out for small polyps (smaller than 2 cm.) a strict follow-up is necessary for the neoplastic polyps only.
MALIGNANT TRANSFORMATION	Cases of adenocarcinoma developing in association with hyperplastic polyps have occasionally been reported ranging from 0% to 13.5%
Histoclinical long-standing follow-up study of hyperplastic polyps of the stomach. Kamiya T, Morishita T, Asakura H, Munakata Y, Miura S, Tsuchiya M.	Am J Gastroenterol 1981 Apr;75(4):275-81 Abstract quote In a series of 2,013 gastric polyps in 1,201 patients, morphological and histopathological studies have been performed. Ninety-three hyperplastic polyps in 56 patients have been followed-up endoscopically and histopathologically for five to 12 years. The incidence of detection of gastric polyps has increased: 1.4% in 1967 to 8.7% in 1979 year by year. Thirty patients (54%) among the 56 showed changes in number, size or shape of polyps during follow-up. Twenty patients (37%) revealed numerical changes (increase in 16 patients, reversion in three patients and vanishing in two patients). Twenty-eight polyps (30%) showed morphological changes, six of them showed continuous enlargement, 18 lesions repeated enlargement, stationary or reduction stages, three lesions were reversed and two polyps disappeared. Histopathologically, three lesions showed transformation from the hyperplastic type to adenoma while demonstrating morphological enlargement. Two of these showed increase in cellular atypia, from the hyperplastic type through adenoma with severe atypia and finally to carcinoma in the polypectomy specimens. From this study, it was concluded that although hyperplastic polyps show changes in size, shape or number with passage of time, malignant changes occur in only a few cases.
TREATMENT	Removal