As mentioned above, MALT lymphomas with high grade component have known to be an advanced disease with worse prognosis than typical MALT lymphomas. de Jong et al.5
revealed only if 1-10% of all tumor cells showed high grade character with or without non-confluent clusters of blasts, the tumor would have worse outcome than pure low grade MALT lymphomas. In our case, the cells had composed an apparent cluster similar to DLBCL. It was a small area, but from biopsy specimens. We could assume larger area in the lesion was occupied by high grade components. Then, we had concluded the lesion had been a high grade MALT lymphoma, however, the tumor had disappeared only in 2 months.
It is known that some gastrointestinal lymphomas show spontaneous regression. But these reports were almost limited to gastric lymphomas, and not defined as MALT lymphomas.7-13
To the best of our knowledge, there are only 5 well-documented cases of MALT lymphoma that showed spontaneous regression; these cases are summarized in the .14-18
None of these patients showed a large-cell component in the pathological specimen. Only one of these cases relapsed with the appearance of DLBCL cells. Our case report presented herein would be the very rare case of MALT lymphoma with a high grade, large-cell component, in which the tumor showed spontaneous regression.
Summary of Spontaneous Regression Cases of the MALT Lymphoma Reported in the English-Language Literature
How could high grade MALT lymphoma can completely disappear in such a short interval? We could not have found out any good answer to this question. We had speculated that the MALT lymphoma in our case developed on a background of some infection, and it could happen that the lymphoma regressed with resolution of the infection, just like some gastric MALT lymphomas are known to regress after the eradication of H. pyrori
. There was some evidence of inflammation in this case, such as increase of the WBC count, elevation of the serum CRP, or the macroscopic appearance of an inflamed terminal ileum on colonoscopy. The association between gastric H. pylori
infection and gastric MALT lymphoma is the most firmly established,19-22
but a number of infections other than H. pylori
have been implicated in the development of MALT lymphoma. However, in our present case, we had failed in finding any evidence of H. pylori
and other infections which include Campylobacter jejuni
through serum antibody test and stool culture. On the other hand, it is believed that eradication therapy would only succeed in cases with low grade MALT lymphomas, based on the contention that only low grade lymphomas exhibit reversible reactivity to infection. The present case shows, however, high grade lymphomas may also show reversible reactivity.
We need to consider the possibility of immunoproliferative small intestinal disease (IPSID) which is endemic in Middle-Eastern and Mediterranean countries. Representative patients of IPSID usually present with malabsorption syndrome, weight loss, and abdominal pain of months' to years' duration and often reveal peripheral edema, clubbing, or an abdominal mass. In addition, the number of circulating lymphocytes is often reduced and levels of serum IgG and IgM would be abnormal. Proximal portion of small intestine is often shifted to abnormal change.23
However, in the present case with lesion at terminal ileum, since no abnormalities in physical examination and in WBC counts or serum Ig were shown, it was very difficult to diagnose the present case as a representative IPSID.
Among the 5 cases cited in , one case showed relapse of the lymphoma, with high grade transformation. Therefore, we believe that in the present case, close-follow-up by colonoscopy is necessary. Until now, 24 months after the lesion was first detected, there has been no evidence of relapse of the lesion through colonoscopic study of this patient.