Carcinoma in hyperplastic polyps of the stomach. An underestimated possibility. Case reports

Poorly differentiated adenocarcinoma with signet-ring cell carcinoma in a hyperplastic polyp of the stomach: report of a case

Hyperplastic polyps (HPs) of the stomach have been reported to be mostly benign. However, in rare cases, carcinomas have been found in HPs. We treated a 59-year-old Japanese male who underwent a total gastrectomy, and a gross examination of the resected stomach revealed a 4.8 x 3.8-cm polyp on the greater curvature of the antrum and multiple small polyps in the whole gastric mucosa. Histologically, the large polyp consisted mainly of hyperplastic foveolar epithelium, while the presence of variously colored lobules demonstrated a poorly differentiated adenocarcinoma mixed with signet-ring cell carcinoma. Hyperplastic polyps should therefore be carefully examined microscopically as a polypectomy specimen and in resected stomach specimens.

Acquired hyperplastic gastric polyps in solid organ transplant patients

OBJECTIVE

We report a series of patients who developed hyperplastic gastric polyps after solid organ transplantation.

METHODS

A retrospective review of patients with solid organ transplantation from January 1997 to December 1999 was performed. Patients with gastric polyps found during endoscopy were included. Demographic data, polyp characteristics (endoscopic and histological), time of endoscopy, and treatment regimens were analyzed.

RESULTS

A total of 10 (seven men, three women) transplanted patients (six cardiac, three liver, and one kidney) with gastric polyps were identified. The median age was 61 yr (27-71 yr), and median time of endoscopy after transplantation was 11 months (3-28 months). Eight patients had endoscopy before or soon after transplantation, with no evidence of polyps. Nine patients had multiple polyps (three or more), and one had a single pedunculated polyp. Polyps were confined to the antrum in eight patients, antrum and body in one patient, and fundus in one patient. All polyps biopsied were found to be hyperplastic and without adenomatous or malignant changes. Cytomegalovirus serology was negative in nine patients. Each patient received standard immunosuppression that included a calcineurin inhibitor and steroids. Steroids were tapered and stopped by 3 months. Azathioprine was added in five patients and mycophenolate mofetil in one patient.

CONCLUSIONS

The development of gastric polyps after organ transplantation has not been previously reported. The development of these gastric polyps (hyperplastic and multiple) is concerning as a malignant potential has been recognized in patients harboring multiple hyperplastic gastric polyps. The exact cause of these polyps is unknown. The association with immunosuppressive therapy as well as the natural history of these acquired hyperplastic gastric polyps needs further investigation.

Hyperplastic polyps of the stomach: associations with histologic patterns of gastritis and gastric atrophy

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.

Carcinoma in gastric hyperplastic polyps. A phenotypic study

One-hundred twelve hyperplastic polyps were analyzed. The aim was to study their malignant transformation. Among them, four hyperplastic polyps harbored adenocarcinoma; two were from our own institution (1.8%). The majority were pedunculated and located in the antrum with an average of 14.5 mm in diameter. The four polyps bore well-differentiated adenocarcinoma. Dysplasia and intestinal metaplasia were detected in two and three polyps, respectively. The cancer and dysplastic foci shared the same type of neutral and acid mucosubstances. p53 oncoprotein was positive in three cancer foci and in the dysplastic areas, and nucleolar organizer region counts were higher in the cancer foci. In conclusion, hyperplastic polyps have malignant potential. Such possibility increases in polyps larger than 14.5 mm. In our cases, the carcinoma foci may have arisen from dysplastic areas. Once the neoplastic changes occur, the cancer cells proliferate and behave as other adenocarcinomas of the stomach.

Possible neoplastic transformation within gastric hyperplastic polyp. Application of endoscopic polypectomy

A total of 263 gastric hyperplastic polyps, which had been removed endoscopically from 202 patients, were clinicopathologically analyzed. Among these polyps, there were nine polyps with neoplastic components (3.4%), corresponding to adenoma in five lesions and mucosal adenocarcinoma in four lesions. Comparing the neoplastic transformed polyps with the pure hyperplastic polyps, there was no significant difference according to age, gender, location, gross appearance, or size. However, the transformed polyps which were located in the lower third of the stomach were larger in size (mean, 20.8 mm) and were more likely to be found among older patients (mean, 75.8 years) than were the pure hyperplastic polyps (mean size and age: 14.5 mm and 61.8 years). These results may indicate the possibility of a different carcinogenesis belonging to gastric hyperplastic polyps by location, and this finding seems to be significant in the application of endoscopic polypectomy.

Signet ring cell carcinoma in hyperplastic polyp

BACKGROUND

A polypectomy was performed on a 68-year-old woman who had three gastric hyperplastic polyps. A focal signet ring cell carcinoma was discovered in one of the polyps, which was 2.2 cm in diameter and was located in the antrum.

METHODS

To study the carcinoma's phenotype expression, special mucin histochemical stainings were performed.

RESULTS

The carcinoma infiltrated only into the mucosa. Intestinal metaplasia was scant. In the neoplasm neutral and foveolar mucin was predominant over acid mucin. The surrounding hyperplastic foveolar epithelium showed positivity for neutral mucin, and the intestinal metaplasia foci for acid mucin.

CONCLUSIONS

This neoplasm has a mixed composition of mucins and shares histochemical characteristics with the surrounding hyperplastic foveolar epithelium.

Case report of a patient with multiple lesions of the stomach, including multiple cancers and an adenomatous polyp

This paper describes an unusual case of an 80-year-old man followed up for multifocal gastric cancers. There were three separate polypoid carcinomas and one adenomatous polyp with no sign of malignancy. We measured the DNA content of the gastric cancer and adenomatous cells obtained from endoscopically biopsied specimens. The adenomatous polyp and one of the cancerous lesions showed DNA diploidy. The other two cancerous lesions showed DNA aneuploidy, with different DNA index (DI) values (1.12 and 1.64, respectively). It is considered that the three cancers arose from different stem lines. However, an operation was not performed because the patient refused gastrectomy, and therefore only conservative follow up has been continued. Presentation of this case is followed by a detailed discussion focusing on the possible development of carcinoma in gastric adenomatous polyps in view of the data from the literature.