Multiple occurrences of primary gastric neoplasma are relatively well known, but few reports have been published regarding the simultaneous presence of gastric carcinoma and gastric malignant lymphoma. A previous study reported that the incidence of coexisting primary malignant lymphoma and adenocarcinoma of the stomach was 0.08% (two of 2 438 adenocarcinoma cases).1 Moreover, most of the adenocarcinomas were smaller and penetrated less than coexisting mucosal-associated lymphoid tissue (MALT) lymphoma. Here, we report a case of synchronous adenocarcinoma and MALT lymphoma of the stomach, but the lesion with lymphoma was focal and smaller than that of adenocarcinoma in size.
A 48-year-old male was referred to our hospital with chief complaint of epigastric pain for three months. Endoscopic examination revealed an elevated lesion located at pylorus, and the biopsy demonstrated a moderately differentiated adenocarcinoma with superficial lamina muscularis invasion. Simultaneously, Helicobacter pylori infection was detected by urease reagent paper. Thus, the patient underwent total gastrectomy. Macroscopically, an ulcer with 2.0 cm in diameter was found, and the cut surface was grayyellow color. We prepared eight pieces of lesional tissues for paraffin embedding and HE section. Microscopically, the lesion was mainly composed of adenocarcinoma. However, metatypical hyperplastic lymphoma cells were found in only one section. Immunohistochemical staining showed positivity for LCA and CD20 in the infiltrated lymphoid cells (Figure 1), but negativity for CD3, CD5, CD45RO, CD10, CK, EMA, CEA, and CK18. Moreover, the lesion with lymphoma was focal and smaller than that of adenocarcinoma in size, which was different from most of the adenocarcinomas that were smaller and penetrated less than coexisting MALT lymphoma reported in literatures.
Since the first case reported by Rabinovitch et al2 less than 100 cases of synchronous occurrence of gastric adenocarcinoma and lymphoma have been published in English medical literatures. The age ranged from 27 to 85 years. Male predominance was observed in both Western and Eastern populations.
The precise mechanism of the coexistence of these neoplasms is unclear. On the one hand, it might be a coincidence rather than a direct relationship, because most of these synchronous tumors reported in literatures arise independently and located at separate areas in stomach. Moreover, some studies proposed that these synchronous tumors develop because one preexisting tumor provokes the other, or the two tumors arise independently as a result of the same carcinogenic agent. Sun-Young Lee et al presented an analysis of the findings of synchronous gastric adenocarcinoma and primary gastric MALT lymphoma cases from 6 012 gastric adenocarcinoma patients and 25 primary gastric MALT lymphoma patients who were operated and found that most of these synchronous tumors were discrete. Moreover, the adenocarcinomas were smaller and penetrated less than coexisting MALT lymphoma reported in previous reports. Their findings suggested that adenocarcinoma might develop after the MALT lymphoma through carcinomatous changes resulted from the chronic irritation of the mucosa. It is considered that lymphomaassociated immunosuppressive state might be a key to the subsequent development of gastric carcinoma. Accordingly, they concluded that there is a possibility that the presence of a primary gastric MALT lymphoma increases the risk of development of gastric adenocarcinoma, as has been suggested by previous studies.
In the present study, only one lesion with ulcer was found. However, microscopic examination revealed that these two tumors were separate, namely adenocarcinoma cells were not found in lymphoma area, and vice versa. Furthermore, the lesion with lymphoma was focal and smaller than that of adenocarcinoma in size, which was different from most of the adenocarcinomas that were smaller and penetrated less than coexisting MALT lymphoma reported in literatures. It seemed to suggest that two lesions were primarily separate, but they integrated into one lesion for a long time.
On the other hand, a close association between H. pylori infection and gastric malignancies not only with adenocarcinomas but also with lymphomas was reported in epidemiological studies. There have been many reports that H. pylori infection, which is thought to be causally related to chronic gastritis, may also be associated with an increased risk of gastric carcinoma.3,4 Recently, several authors have strongly suggested that H. pylori infection may play an important role in the pathogenesis of gastric lymphoma.5 In addition, the causative association with this chronic stimulus was well established for gastric MALT lymphoma, and cure of the infection can lead to complete remission of early lymphoma in about 80% of cases. However, some authors have reported low incidence of coexistence of gastric adenocarcinoma and malignant lymphoma. Ishihama et al reviewed 7 130 consecutive cases of resected gastric adenocarcinoma over 32 years and found only four cases (0.06%) coexistence of gastric malignant lymphoma. This is consistent with a report by Noda et al showing that the incidence of gastric adenocarcinoma which has coexisting primary malignant lymphoma is only 0.08% (two of 2 438 cases). In the present study, H. pylori infection was detected by urease reagent paper when endoscopic examination was performed, suggesting that the whole lesion was related to H. pylori infection. However, we could not determine whether the lesion was adenocarcinoma or lymphoma, or both of them.
In conclusion, the synchronous occurrence of both gastric adenocarcinoma and malignant gastric lymphoma in the same patient is extremely rare. In the present study, the lesion with lymphoma was focal and smaller than that of adenocarcinoma in size, which was different from most of the adenocarcinomas that were smaller and penetrated less than coexisting MALT lymphoma reported in literatures. It seemed to suggest that two lesions were primarily separate, but they integrated into one lesion for a long time.
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