Gastric inverted hyperplastic polyp. Report of four cases and relation to gastritis cystica profunda

Clinicopathologic and endoscopic characteristics of ten patients with gastric hamartomatous inverted polyp: a single center case series

BACKGROUND

Gastric hamartomatous inverted polyps (GHIPs) are not well characterized and remain diagnostically challenging due to rarity. Therefore, this study aims to investigate the clinicopathologic and endoscopic characteristics of patients with GHIP.

METHODS

We retrospectively reviewed clinicopathologic and endoscopic features of ten patients with GHIP who were admitted to Beijing Friendship Hospital from March 2013 to July 2022. All patients were treated successfully by endoscopic resection.

RESULTS

GHIPs were usually asymptomatic and found incidentally during gastroscopic examination. They may be sessile or pedunculated, with diffuse or local surface redness or erosion. On endoscopic ultrasonography, the sessile submucosal tumor-type GHIP demonstrated a heterogeneous lesion with cystic areas in the third layer of the gastric wall. Histologically, GHIPs were characterized by a submucosal inverted proliferation of cystically dilated hyperplastic gastric glands accompanied by a branching proliferation of smooth muscle bundles. Inflammatory cells infiltration was observed in the stroma, whereas only one patient was complicated with glandular low-grade dysplasia. Assessment of the surrounding mucosa demonstrated that six patients (60%) had atrophic gastritis or Helicobacter pylori-associated gastritis, and four patients (40%) had non-specific gastritis. Endoscopic resection was safe and effective.

CONCLUSIONS

GHIPs often arise from the background of abnormal mucosa, such as atrophic or H.pylori-associated gastritis. We make the hypothesis that acquired inflammation might lead to the development of GHIPs. We recommend to make a full assessment of the background mucosa and H. pylori infection status for evaluation of underlying gastric mucosal abnormalities, which may be the preneoplastic condition of the stomach.

Large gastric hamartomatous inverted polyp accompanied by advanced gastric cancer: A case report

BACKGROUND

Gastric hamartomatous inverted polyps (GHIPs) are benign polyps of the gastric submucosal layer. Currently there are 52 reported cases in the English literature. According to a literature review, approximately 27% of GHIPs show a coexisting carcinoma.

CASE SUMMARY

A 66-year-old man was referred to our institution with ulcerative lesions detected on esophagogastroduodenoscopy (EGD) during a regular check-up. Other medical findings were nonspecific. The lesions had borderline histologic features that could not exclude malignancy and were followed up with three EGDs and biopsies at intervals of 3 mo. The latest biopsy was revealed as an adenocarcinoma. A total gastrectomy was performed to remove the tumor. The surgical specimen revealed a 6.9 cm × 4.5 cm sized GHIP with a coexisting 1.6 cm sized well-differentiated adenocarcinoma which extended to the muscularis propria. The malignancy did not originate from the GHIP but showed an overlap.

CONCLUSION

A large GHIP, which was unusually presented as an ulcerative lesion, was surgically removed, and was accompanied by advanced gastric cancer. Regular follow-up and thorough examinations of ulcerative lesions with equivocal biopsy have resulted in appropriate diagnosis and treatment. Therefore, aggressive intervention may be beneficial if GHIP is suspected.

Synchronous gastric MALT lymphoma and gastric adenocarcinoma of fundic gland type arising from a hamartomatous inverted polyp in a Helicobacter pylori naive patient

We present a rare case that showed the coexistence of gastric cancer and mucosa-associated lymphoid tissue (MALT) lymphoma in Helicobacter pylori-naive stomach. A 72-year-old man was followed up after surgery for epithelial carcinoma of the glottis at the Department of Otolaryngology. He underwent an upper gastrointestinal endoscopy for an abnormal PET-CT accumulation, which revealed gastric adenocarcinoma of fundic gland type in the gastric fundus and MALT lymphoma in the upper gastric body. Hence, we performed an endoscopic submucosal dissection for gastric cancer and diagnosed gastric adenocarcinoma of fundic gland type derived from a hamartomatous-inverted polyp. Subsequently, Gastric MALT lymphoma was treated with radiation therapy because the API2-MALT1 gene was positive and the Helicobacter pylori infection was negative. A complete response was observed. Even in Hp-naive stomachs, cases such as the present case are complicated by special types of gastric cancer and MALT lymphoma, and endoscopic examination should be performed with these diseases in mind.

Gastric hamartomatous inverted polyp: Report of three cases with a review of the endoscopic and clinicopathological features

Objectives

A gastric hamartomatous inverted polyp (GHIP) is a rare submucosal tumor characterized histopathologically by a submucosal inverted proliferation of cystically dilated hyperplastic gastric glands. Only 42 GHIPs have been reported in English literature. Few GHIPs have been reported to accompany adenocarcinomas. We reported on three patients with a GHIP and reviewed the clinicopathological and endoscopic features of GHIPs.

Methods

This study included two men and one woman with a GHIP. The endoscopic, histopathological, and immunohistochemical features of the endoscopically resected specimens were analyzed. A gene mutation analysis was also performed.

Results

All the tumors were located in the body of the stomach, with a median size of 20 mm. Two tumors were sessile, and the remaining tumor had a pedunculated appearance. The overlying mucosa mainly appeared normal but was reddish in one tumor. The histopathological examination of the tumors revealed a well-circumscribed and lobular submucosal proliferation of cystically dilated hyperplastic glands. The immunohistochemical analysis revealed that the MUC5AC-positive foveolar epithelium was located in the center, and MUC6-positive pseudo-pyloric or pepsinogen-I and H⁺/K⁺ ATPase-positive fundic-type glands were located at the periphery of two tumors. No carcinomatous components were noted in any of the tumors. Moreover, no significant mutations in oncogenes or tumor suppressor genes were noted.

Conclusions

Our review revealed that approximately three fourths of GHIP cases showed an submucosal tumor-like feature, whereas endoscopic features, including the endoscopic ultrasonography findings, were not characteristic. Because an endoscopic diagnosis of a GHIP may be difficult, complete endoscopic resection may be required for a pathological diagnosis.

Activating KRAS and GNAS mutations in heterotopic submucosal glands of the stomach

BACKGROUND

The heterotopic submucosal gland (HSG) is a common incidental finding in gastrectomy specimens. The majority of HSGs are small incidental lesions, which are also known as gastritis cystica profunda. However, larger lesions may appear as an inverted growth of well-organized mucosa referred to as gastric inverted polyps.

METHODS

To determine whether genetic alterations are involved in HSG development, we analyzed 63 gastric HSG lesions using targeted next-generation sequencing and immunohistochemistry.

RESULTS

Histologically, HSG lesions consistently had areas of pyloric gland differentiation with variable extent of foveolar differentiation. Although the background mucosa showed intestinal metaplasia in most cases (98%), intestinal-type epithelium was seen in only one HSG lesion (2%). Sequencing analysis identified activating KRAS, BRAF, CTNNB1, and GNAS mutations in 34 (54%), 1 (2%), 1 (2%), and 7 (11%) lesions, respectively. HSG lesions harboring a KRAS mutation were more likely to present extensive foveolar differentiation (P = 0.013) and absence of parietal cells (P = 0.0081). Five HSG lesions had a dysplastic component, and concordant genetic alterations were detected between the non-dysplastic and dysplastic areas of two lesions that were successfully analyzed. Immunohistochemical staining demonstrated diffuse expression of mutant KRAS protein in lesions with the most common genetic alteration, KRAS G12D.

CONCLUSIONS

Our study demonstrated that a major proportion of HSGs were proliferative lesions associated with oncogenic mutations, with more than half of lesions harboring activating KRAS mutations.

Gastric Inverted Polyps-Distinctive Subepithelial Lesions of the Stomach: Clinicopathologic Analysis of 12 Cases With an Emphasis on Neoplastic Potential

Gastric inverted polyps (GIPs) are rare gastric polyps characterized by a submucosal inverted growth of mucosal components. Because of their rarity, they are not well characterized and are diagnostically challenging. We examined 12 cases of GIPs arising in 8 male and 4 female patients (mean age: 56 y). Most GIPs (11/12, 92%) occurred as a single, rounded subepithelial lesion in the body or fundus (mean size: 14.9 mm). Histologically, GIPs consisted of gastric-type glandular epithelium and smooth muscle component, growing in an endophytic manner; however, they displayed significant morphologic variations. We classified GIPs into 3 subtypes by the following features: communication with the mucosal surface, smooth muscle boundary, and tissue organization. The defining characteristics of type 1 were a mucosal communicating structure at the center and a well-defined smooth muscle boundary, resulting in a characteristic low-magnification morphology of a round vase. Type 2 had an organized glandular proliferation with smooth muscle boundary and no central communicating structure. Type 3 GIPs had no mucosal communicating structure or smooth muscle boundary; its key histologic feature was the lobular organization pattern produced by proliferations of cystic or hyperplastic glands and smooth muscle. All type 1 GIPs exhibited coexisting adenocarcinoma (3 cases) or stromal proliferation (3 cases). Three patients with type 2 GIP had separate adenocarcinoma. None of the type 3 GIPs had accompanying carcinoma. In conclusion, GIPs are a heterogenous group showing different morphology and clinical behavior. Notably, type 1 GIP could be considered a precancerous lesion with the potential to develop adenocarcinoma.

Diagnosis and treatment of gastric hamartomatous inverted polyp (GHIP) using a modified combination of laparoscopic and endoscopic approaches to neoplasia with a non-exposure technique (modified CLEAN-NET): a case report

BACKGROUND

Gastric hamartomatous inverted polyp (GHIP) is a pathological condition where enlarged gastric glands with cystic dilatation grow in the submucosa. It is difficult to excise the tissue due to its location. In addition, even if the tissue is taken correctly, making an accurate diagnosis is difficult due to foveolar epithelium in the tissue, which can be misdiagnosed as gastric mucosal epithelium. Thus, an accurate diagnosis of GHIP is rarely established from a biopsy alone preoperatively. We here report a case of GHIP with a central dimple, which was diagnosed and treated using a modified combination of laparoscopic and endoscopic approaches to neoplasia with a non-exposure technique (modified CLEAN-NET).

CASE PRESENTATION

A 60-year-old man with a submucosal tumor (SMT) in the stomach was referred to our hospital by a primary care doctor. On examination, a gastrointestinal stromal tumor was suspected. Modified CLEAN-NET was performed for diagnostic and therapeutic purposes. The histopathological examination of the resected specimen showed an enlarged gland duct in the submucosal layer. This finding, along with immunostaining results, led to the diagnosis of GHIP. The postoperative course was uneventful without any symptoms.

CONCLUSIONS

GHIP should be considered among the differential diagnoses of SMT of the stomach. Modified CLEAN-NET may be beneficial in the removal of SMTs such as GHIP with a central dimple because it can avoid stomach deformation of the stomach and tumor dissemination.

Bile reflux gastritis cystica profunda: A case report and literature review

RATIONALE

Gastritis cystica profunda (GCP) is a rare gastric lesion involving cystic dilation of the gastric glands extending into the submucosa. It is usually observed at anastomotic sites in the stomach of patients who have undergone gastric procedures. Bile reflux GCP is rare in patients who have not undergone gastric surgery. Here, we report a rare case of a patient with GCP associated with bile reflux, who had no history of gastric surgery.

PATIENT CONCERNS

A 50-year-old man presented with intermittent abdominal fullness for 2 years, along with nausea. He had never undergone gastric surgery. Endoscopic ultrasonography (EUS) showed a thickened gastric wall and an echo-poor submucosal layer of the gastric fundus. A 3 cm × 2 cm × 1.5 cm lesion was noted.

DIAGNOSIS

Bile reflux GCP INTERVENTIONS:: Endoscopic retrograde cholangiopancreatography and endoscopic submucosal dissection (ESD) were performed, and the lesion was removed. Conventional pathological examination revealed GCP with glands hyperplasia and a yellow-brown deposit, which was considered bile. The findings were consistent with a diagnosis of GCP without malignancy.

OUTCOMES

Upper gastrointestinal barium meal revealed postoperative changes at the gastric fundus. Gastroscopy performed at 6 months after surgical resection showed superficial gastritis with bile reflux.

LESSONS

The findings suggest that GCP etiology varies and that GCP can be caused by bile reflux but without malignancy. Additionally, GCP is not limited to patients who have previously undergone gastric surgery. Moreover, it is difficult to identify. EUS and ESD might be good approaches for the diagnosis and treatment of GCP.

Inverted gastric adenocarcinoma of fundic gland mucosa type colliding with well differentiated adenocarcinoma: A case report

RATIONALE

Gastric adenocarcinoma of fundic gland mucosa type (GA-FGM) is a rare tumor composed of atypical cells with differentiation toward the fundic gland as well as the foveolar epithelium. Including our case, only 9 cases of GA-FGMs were reported from 2010 to 2016.

CONCERNS OF THE PATIENT

An 87-year-old man was referred to our institution for endoscopic resection of a gastric lesion. The tumor was classified as type 0-I + IIa according to the Paris classification. Magnifying endoscopy with narrow band imaging (ME-NBI) revealed different structures of crypts and vessels among the components, illustrating the collision of 2 types of gastric cancer.

INTERVENTIONS

We performed endoscopic submucosal dissection and successfully removed the tumor en bloc.

OUTCOMES

The histological findings differed markedly between the 0-I lesion and the 0-IIa lesion. The superficial part of the 0-I lesion consisted of a papillary structure, and the deeper part consisted of a tubular structure that showed inverted downward growth to the submucosal layer with the lamina muscularis mucosae. Immunohistochemically, the superficial part of the 0-I lesion was positive for MUC5AC, which had differentiated to foveolar epithelium. The deeper part was positive for pepsinogen-I and MUC6, which had differentiated to fundic gland. The 0-I lesion was diagnosed as gastric phenotype of adenocarcinoma differentiated to fundic gland mucosa with upward growth in the superficial part and downward growth in the deeper part. The 0-IIa lesion was composed of a tubular structure positive for MUC2, and it was diagnosed as an intestinal phenotype of well differentiated adenocarcinoma. The boundary was clear, and no transitional tissue was observed between the 0-I and 0-IIa lesions, suggesting that the 0-I + IIa lesion was a gastric collision tumor of GA-FGM and well differentiated adenocarcinoma.

LESSONS

We herein report the first case of inverted GA-FGM colliding with well differentiated adenocarcinoma. ME-NBI can be used to diagnose GA-FGM even if the lesion collides with other types of adenocarcinoma.

[Inverted Hyperplastic Polyp in Stomach: A Case Report and Literature Review]

An inverted hyperplastic polyp (IHP) found in stomach is rare and characterized by downward growth of hyperplastic mucosal component into the submucosa. Because of such characteristic, IHP can be misdiagnosed as subepithelial tumor or malignant tumor. In fact, adenocarcinoma was reported to have coexisted with gastric IHP in several previous reports. Because only 18 cases on gastric IHP have been reported in English and Korean literature until now, pathogenesis and clinical features of gastric IHP and correlation with adenocarcinoma have not been clearly established. Herein, we report a case of gastric IHP which was initially misdiagnosed as gastrointestinal stromal tumor and resected using endoscopic submucosal dissection. Literature review of previously published case reports on gastric IHP is also presented.

Gastric Hamartomatous Polyps-Review and Update

Gastric polyps are frequently encountered on endoscopic examinations. While many of these represent true epithelial lesions, some of the polyps may result from underlying stromal or lymphoid proliferations or even heterotopic tissue. Histologic examination is essential for accurate typing of the polyps to predict malignant potential and underlying possible genetic abnormalities. The focus of this review is on gastric hamartomatous polyps, which are relatively rare and diagnostically challenging. Though most of the gastric hamartomatous polyps are benign, certain types are associated with increased malignant potential. These include certain polyps associated with specific genetic familial polyposis syndromes and gastric inverted hamartomatous polyps. Identification of these polyps can result in the prevention or early diagnosis of gastric carcinoma and also help in the identification of family members with polyposis syndromes. The aim of this review is to categorize gastric hamartomatous polyps and aid in the identification of high-risk categories.

Gastritis profunda cystica presenting as gastric outlet obstruction and mimicking cancer: A case report

Gastritis cystica profunda (GCP) is a rare, benign lesion of the stomach characterized by polypoid hyperplasia and/or ulcerated mucosal lesion and cystic dilatation of the gastric glands extending into the submucosa or muscularis propria of the stomach. Its etiology and pathogenesis are still incompletely understood. The most important factor is assumed to be a history of prior gastric surgery. We herein present a case of a young adult female with upper gastrointestinal (GI) symptoms. She underwent upper GI endoscopy twice, which revealed pyloric narrowing and intramural mass. Gastric endoscopic mucosal biopsies were performed, but no tumor was identified and her symptoms persisted. Imaging studies also revealed a mass lesion. Open laparotomy and partial gastrectomy with histopathology of the resected specimen revealed the true nature of the lesion. Surgery also improved her symptoms. GCP should be kept in the differential diagnosis of gastric mural mass lesions.

Gastric inverted hyperplasic polyp composed only of pyloric glands: a rare case report and review of the literature

Inverted hyperplastic polyp (IHP) in stomach is a rare benign gastric polypoid lesion, characterized by downward growth of hyperplastic mucosal glands into the submucosal layer. In most previous reported cases, gastric IHP showed mixtures of fundic-type gland, pyloric-type gland, and foveolar-type epithelium. Also, a case of IHP composed of only one type of gland is extremely rare. This report describes a case of a 70-year-old man with gastric IHP, composed only of pyloric-type gland. It was removed completely by endoscopic submucosal dissection, and patient showed no recurrence over 2 years after treatment.

A rare precursor of gastric tumor

Gastritis cystica profunda (GCP) is a rare tumor precursor which occurs more commonly in patients who have undergone previous gastric surgery. The non-specific symptoms and radiographic appearance of this tumor mimic those of other hyperproliferative conditions, making diagnosis difficult. This is a pre-malignant condition and may lead on to carcinoma of the stomach. Here we report a 57-year-old female with no previous gastric surgeries, who presented to us with epigastric abdominal pain. Her work-up included an upper endoscopy, which revealed fundic polyps. Her fundal biopsies were consistent with GCP.

Two rare gastric hamartomatous inverted polyp cases suggest the pathogenesis of growth

Gastric hamartomatous inverted polyps (GHIP) are difficult to diagnose accurately because of inversion into the submucosal layer. GHIP are diagnosed using the pathological characteristics of the tumor, including the fibroblast cells, smooth muscle, nerve components, glandular hyperplasia, and cystic gland dilatation. Although Peutz-Jeghers syndrome, juvenile polyposis, and Cowden disease are hereditary, it is rare to encounter 2 cases of monostotic and asymptomatic gastric hamartomas. The pathogeneses of hamartomatous inverted polyps and inverted hyperplastic polyps remain controversial because of the paucity of reported cases. There are 3 hypotheses regarding the pathogenesis of complete gastric inverted polyps. Based on our experience with 2 successive, rare GHIP cases, we affirm the hypothesis that after a hamartomatous change occurs in the submucosal layer, some of these components are exposed to the gastric mucosa and, consequently, form a hypertrophic lesion. In Case 1, our hypothesis explains why a tiny hypertrophic change was first detected on the top of the submucosal tumor using a detailed narrow band imaging-magnified endoscopy. There was no confirmation that the milky white mucous and calcification structures were exuding directly from the biopsy site like Case 1, and in Case 2 the presence of this mucous was indirectly confirmed during an endoscopic submucosal dissection (ESD). Regarding the pathogenesis of GHIP, a submucosal hamartomatous change may occur prior to the growth of hypertrophic portions. An en bloc resection using ESD is recommended for treatment.

Gastritis cystica profunda recurrence after surgical resection: 2-year follow-up

BACKGROUND

Gastritis cystica profunda (GCP) is an uncommon disease characterized by multiple cystic gastric glands within the submucosa of the stomach.

CASE DESCRIPTION

Here, we present a case of a 63-year-old man with intermittent epigastric discomfort in whom gastroscopy revealed multiple irregular elevated nodular lesions with smooth surfaces at the anterior of the antrum. Surgical resection of the nodular lesions was performed, and the diagnosis of gastritis cystica profunda (GCP) was confirmed by histological examination. Another elevated nodular lesion approximately 10 mm in diameter with an ulcer was found on the gastric side of the remnant stomach near the resection side from 6 to 24 months after the surgical resection. Endoscopic ultrasonography (EUS) and repeated biopsies of the new elevated lesion were performed. Homogeneous, anechoic masses originating from the submucosa without gastric adenocarcinoma in histological examination showed GCP recurrence may occur.

CONCLUSIONS

We report a case of GCP recurrence within 6 months after surgical resection. GCP should be considered in the differential diagnosis of elevated lesions in the stomach.

A pedunculated submucosal lesion in the stomach with inverted downgrowth

A 70-year-old man with a gastric lesion was referred to our hospital because of an unusual pedunculated lesion in the gastric body. Endoscopic ultrasound showed scattered cystic lesions within a heterogeneous area confined to the submucosal layer. Endoscopic mucosal resection was performed to obtain a precise diagnosis, as well as for removal. The lesion was histopathologically diagnosed as a heterotopic submucosal gland. We herein describe this rare type of gastric polyp and provide a literature review.

A case of gastric inverted hyperplastic polyp found with gastritis cystica profunda and early gastric cancer

A gastric inverted hyperplastic polyp is a rare type of gastric polyp and is characterized by downward growth of a variety of mucosal components into the submucosa. The polyp consists of columnar cells resembling foveolar epithelium and pyloric gland epithelium and can coexist with gastritis cystica profunda. Frequently, adenocarcinoma can coexist, but the relation is not clear. A 77-year-old male underwent endoscopic submucosal dissection due to early gastric cancer. A gastric inverted hyperplastic polyp was found in the removed specimen and gastric cystica profunda was also found. We report a case of gastric inverted hyperplastic polyp coexisting with gastric cystica profunda and gastric adenocarcinoma.

Multifocal Adenocarcinomas Arising within a Gastric Inverted Hyperplastic Polyp

We present herein the occurrence of multifocal adenocarcinomas with a minute signet ring cell carcinoma that arose within a gastric inverted hyperplastic polyp (IHP) in a 40-year-old woman. Endoscopic ultrasonography demonstrated a heterogeneous hypoechoic mass in the third layer of the gastric wall. The endoscopic submucosal dissection specimen measuring 3.5×3.2×1.8 cm was a well-circumscribed protruding lesion that had a slit-shaped cavity. Histologically, the lesion consisted mainly of endophytic proliferation of hyperplastic columnar cells resembling normal foveolar epithelium. In addition, six foci of adenocarcinomas and a minute focus of signet ring cell carcinoma were randomly distributed in the superficial and deep regions. The adenocarcinoma was gradually transitioning from dysplasia, while the signet ring cell carcinoma was surrounded by hyperplastic foveolar epithelium. This is the first report of a gastric IHP with multifocal intramucosal adenocarcinomas and a signet ring cell carcinoma, and endoscopic submucosal dissection is used to completely resect it.

Targeted deletion of Kcne2 causes gastritis cystica profunda and gastric neoplasia

Gastric cancer is the second leading cause of cancer death worldwide. Predisposing factors include achlorhydria, Helicobacter pylori infection, oxyntic atrophy and TFF2-expressing metaplasia. In parietal cells, apical potassium channels comprising the KCNQ1 α subunit and the KCNE2 β subunit provide a K⁺ efflux current to facilitate gastric acid secretion by the apical H⁺K⁺ATPase. Accordingly, genetic deletion of murine Kcnq1 or Kcne2 impairs gastric acid secretion. Other evidence has suggested a role for KCNE2 in human gastric cancer cell proliferation, independent of its role in gastric acidification. Here, we demonstrate that 1-year-old Kcne2^−/− mice in a pathogen-free environment all exhibit a severe gastric preneoplastic phenotype comprising gastritis cystica profunda, 6-fold increased stomach mass, increased Ki67 and nuclear Cyclin D1 expression, and TFF2- and cytokeratin 7-expressing metaplasia. Some Kcne2^−/−mice also exhibited pyloric polypoid adenomas extending into the duodenum, and neoplastic invasion of thin walled vessels in the sub-mucosa. Finally, analysis of human gastric cancer tissue indicated reduced parietal cell KCNE2 expression. Together with previous findings, the results suggest KCNE2 disruption as a possible risk factor for gastric neoplasia.

Hamartomatous inverted polyp successfully treated by endoscopic submucosal dissection

We report a case of gastric hamartomatous inverted polyps that are a rare histological type of gastric polyp and difficult to diagnose. Gastric submucosal tumor was detected by upper gastrointestinal X-ray series in 37-year-old man. Endoscopy revealed a submucosal tumor (SMT) , which eroded with a depression on its surface in the fornix. Endoscopic ultrasonography showed a heterogeneous tumor in the third layer. Endoscopic submucosal dissection (ESD) was performed to resect the tumor completely. The pathological diagnosis was a gastric hamartomatous inverted polyp. The patient was later discharged without any complications. Hamartomatous inverted polyps without a stalk are classified as the SMT type because the tumor is inverted down growth into the submucosal layer, otherwise polyps with a stalk are classified as the polyp type. All of the polyps were resected endoscopically, however, surgical resection was performed for those of the SMT type, because it is difficult to remove this type completely by en-block resection using conventional EMR technique. ESD method may be indicated for SMT-type hamartomatous inverted polyps.

Adenocarcinoma arising in gastric inverted hyperplastic polyp: a case report and review of the literature

A 54-year-old man, found to have a submucosal tumor in the stomach by double contrast roentgenography, endoscopy, and endoscopic ultrasonography, underwent a laparoscopic partial gastrectomy. The pathological examination revealed that the lesion, measuring 45 mm x 35 mm, was an inverted hyperplastic polyp (IHP) located in the submucosal layer and consisting mostly of columnar cells resembling foveolar epithelium and pyloric gland cells. Notably, adenocarcinoma with adjacent dysplasia was observed in the submucosal glands. Transition from hyperplasia to dysplasia and from dysplasia to adenocarcinoma was noted. The adenocarcinoma component was intensely and diffusely positive for p53 overexpression, while the dysplasia component showed only weak and focal positivity, suggesting a role of p53 mutation in the dysplasia-carcinoma sequence. Gastric IHP is very rare, and only 31 cases (in 29 patients) have been reported. Five of these IHPs coexisted with gastric adenocarcinomas, which had all developed separately from the IHP lesions. Therefore, this is the first case of adenocarcinoma arising within gastric IHP itself.