Depressed gastric-type adenoma in nonatrophic gastric mucosa without Helicobacter pylori infection

Gastric adenoma is a benign epithelial tumor and is frequently observed as an elevated rather than a depressed lesion and in Helicobacter pylori-infected mucosa [1]. We describe a rare case of depressed gastric-type adenoma in nonatrophic gastric mucosa without H. pylori infection.

A 59-year-old man was referred to our hospital for further examination and treatment of gastric neoplasia. Endoscopy revealed a whitish depressed lesion, 10 mm in diameter, in the greater curvature of the lower gastric body ([Fig. 1]). Atrophy and intestinal metaplasia were not observed in the background gastric mucosa ([Fig. 2]). Furthermore, serum H. pylori antibody, serum pepsinogen, and urea breath tests were all negative, indicating that the gastric mucosa was not infected by H. pylori.

Fig. 1 Endoscopic image showing a whitish depressed lesion, 10 mm in diameter, in the greater curvature of the lower gastric body.

Fig. 2 a, b Atrophy and intestinal metaplasia were not observed in the background gastric mucosa.

Magnifying endoscopy using narrow-band imaging showed an irregular microsurface pattern with round and oval pits and a slightly irregular microvascular architecture with discordant looped vessels ([Fig. 3]) in the lesion. In accordance with the vascular pattern, surface pattern (VS) classification system [2], these findings were categorized as an irregular microsurface pattern and an irregular microvascular pattern with a demarcation line, which were indications of malignancy. Thus, although the biopsy specimen showed adenoma ([Fig. 4]), endoscopy revealed malignant findings. Endoscopic submucosal resection was performed for histologic evaluation ([Video 1]).

Fig. 3 Magnifying endoscopy with narrow-band imaging showed an irregular microsurface pattern with round and oval pits and slightly irregular microvascular architecture with discordant looped vessels.

Fig. 4 a, b Histological examination showed gastric-type adenoma.

Video 1 Depressed gastric-type adenoma in nonatrophic gastric mucosa without Helicobacter pylori infection: endoscopic submucosal resection performed for histologic evaluation.

Histologically, the tumor cells showed gastric-type adenoma. Immunohistochemically, the tumor cells were positive for mucin (MUC) 5AC and MUC6 but negative for MUC2 and CD10 ([Fig. 5 a – d]).

Fig. 5 Immunohistochemical analysis indicated that the lesion was a gastric-type adenoma. The tumor cells were: a mucin (MUC) 5AC-positive; b MUC6-positive; c MUC2-negative; and d CD10-negative.

There are a few reports on depressed-type gastric adenomas in H. pylori-noninfected gastric mucosa, and some reports state that some gastric adenomas may progress to adenocarcinoma [3]. There is no consensus about the treatment for gastric adenoma in H. pylori-noninfected gastric mucosa. However, we recommend that endoscopic submucosal dissection as a total biopsy is also necessary. It is important to accumulate further cases to clarify the characteristics of gastric adenomas in H. pylori-noninfected gastric mucosa.

Endoscopy_UCTN_Code_CCL_1AB_2AD_3AB

• References

• 1 Tamai N, Kaise M, Nakayoshi T. et al. Clinical and endoscopic characterization of depressed gastric adenoma. Endoscopy 2006; 38: 391-394
• 2 Yao K, Anagnostopoulos GK, Ragunath K. Magnifying endoscopy for diagnosing and delineating early gastric cancer. Endoscopy 2009; 41: 462-467
• 3 Taniyama D, Taniyama K, Kuraoka K. et al. Long-term follow-up study of gastric adenoma; tumor-associated macrophages are associated to carcinoma development in gastric adenoma. Gastric Cancer 2017; 20: 929-939