The presentation of HL with an extranodal location is quite uncommon [3
]. Primary HL involving the gastrointestinal tract is exceedingly rare and has been reported (in descending order) in the stomach, small intestine, large intestines, and esophagus [3
]. In 1961, Dawson et al. [10
] proposed a set of criteria for the diagnosis of primary gastrointestinal HL from secondary involvement because lymphoma of the gastrointestinal tract is seen more commonly in the context of disseminated disease. These criteria included 1) absence of peripheral lymphadenopathy at the time of presentation, 2) lack of enlarged mediastinal lymph nodes, 3) normal results for a complete blood count and differential, 4) predominance of the bowel lesion, despite the presence of disease in adjacent lymph nodes, and 5) absence of any lymphomatous involvement of the liver or spleen. Our case fulfilled all of the aforementioned criteria. Based on immunohistochemical results, in addition to those criteria listed above, the frequency of primary gastric HL has been reported as approximately less than 1% of all gastric lymphomas [2
Histologically, the lymph node architecture of HL is effaced by a variable number of mononuclear Hodgkin's cells and multinucleated Reed-Sternberg (HRS) cells admixed with a rich inflammatory background. However, in some cases, careful differential diagnosis through the use of a full panel of immunohistochemical markers is necessary to exclude other disease entities, in which there are similarities with both histopathological features and the presence of HRS-like cells in tumors [4
]. Phenotypically, the HRS cells were positive for CD30 in nearly all cases, for CD15 in the majority (75 to 85%) of cases and variable expressions of B-cell markers such as CD20 and CD79a [4
]. In addition, these cells are negative for EMA, T-cell markers and ALK-1. Morphologically, our case can be differentiated from anaplastic large cell lymphoma (ALCL), undifferentiated carcinoma, and the anaplastic variant of diffuse large B-cell lymphoma (DLBCL). Since our patient demonstrated CK-negative, CEA-negative and diffuse CD30-positive with the immunohistochemical staining results, we easily excluded the diagnosis of undifferentiated carcinoma and the anaplastic variant of DLBCL. We eliminated the possible diagnosis of ALCL, since the CD15 status of HRS cells was different in our case from that observed in previous reports [3
]. However, we finally diagnosed our case as HL of the stomach, because EMA and ALK-1 were negative, and B-cell markers, such as CD20 and CD79a, were positive, which was in accordance with results from a previous report [4
The epidermiologic and pathogenic association of HL with the EBV has been established even though its presence is not diagnostic of HL [8
]. However, EBV infection was not present in the pathologic portion of the stomach analyzed in our case. Regarding cases of HL located at unusual sites, such as gastric HL, some authors have suggested that the gastric marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT) type, which is similar to DLBCL, may be a precursor lesion for CHL [9
]. The results of tests for H. pylori
were positive in our case; however, none of our findings suggested the presence of gastric MALT lymphoma. Therefore, the pathogenesis of our case is not clear because the EBV infection was not proven and the absence of gastric MALT lymphoma.
The prognosis of gastric HL is poor with 45 to 60% of patients dying within the first year of diagnosis [4
]. Therefore gastric HL has been treated surgically with postoperative chemo- or radiotherapy [4
]. Postoperative therapy may be necessary because gastric HL may represent only one expression of systemic lymphoma, and another portion of the lymphatic system may develop malignancy postoperatively. Our patient underwent laparoscopic gastric wedge resection and then received six cycles of adriamycin-vincristine-doxorubicin chemotherapy, as a precautionary measure. No recurrent disease was observed after four months of follow-up.
In conclusion, when we encounter a case involving anaplastic tumors of the stomach, we must be aware of the existence of gastric HL in spite of its rarity and make a precise diagnosis on the basis of histological findings and essential immunohistochemical analyses.