Multiple Primary Rectal and Gastric Mucosa Lymphoid Lesions – Marginal Zone Non-Hodgkin B-Cell Lymphoma

Excerpt

A 56-year-old man was referred to our hospital with a 2-year history of abdominal pain and increased stool frequency. Colonoscopy showed a non-granular laterally spreading tumor (LST)-like elevated lesion in the upper rectum, about 2.0 cm in diameter (Fig. 1A and B). Endoscopic mucosal resection was performed to remove the tumor (Fig. 1C). The histopathological detection of the specimen showed lymphoepithelial proliferation (Fig. 1D). On immunostaining, the lesion stained strongly with CD20 (Fig. 1E), which was consistent with mucosa-associated lymphoid tissue (MALT) lymphoma. Four months later, a follow-up colonoscopy showed regression of the lesion (Fig. 1F). Considering the ill-defined rectal lesions and potential systemic involvement of MALT lymphomas in the patient, 18F-FDG PET-CT was evaluated and showed normal features of the rectum but diffuse lesions in the stomach. Then, we performed esophagogastroduodenoscopy, which presented discolored mucosa and redness with clear boundary in the gastric fundus and gastric body (Fig. 2A), as well as multiple erythema and diffuse granular flat ridges in the gastric antrum and gastric angle (Fig. 2B). Surprisingly, microscopic examination of the multiple gastric lesions confirmed MALT lymphomas, specifically characterized by lymphoepithelial proliferation (Fig. 2C and D) and the strong positive expression of CD20 (Fig. 2E and F). The patient had no history of autoimmune diseases, and human immunodeficiency virus is definitively excluded by serologic test. White blood cell counts, CA19.9, and CEA values were normal. Serum electrophoresis confirmed no monoclonal band. Bone marrow aspiration revealed no lymphoma cells. Finally, the patient received the diagnosis of multiple primary rectal and gastric MALT lymphoma based on these findings. After the failure of repeated Helicobacter pylori eradication and the persistence of lesions in the stomach, rituximab initiation was commenced. MALT lymphoma arising in lymphoid populations is considered as marginal zone non-Hodgkin B-cell lymphomas. The rectum is the rarely affected organ although the most common site of involvement is the stomach [1]. Colorectal MALT lymphomas may present as a submucosal tumor or coarse granular lesions [2, 3]. Chemotherapy or radiotherapy is considered as the second-line therapy after the failure of Helicobacter pylori eradication or positive resection margin. It is a rare case for this patient with MALT lymphomas involving both the stomach and rectum. The patient received 3 intravenous injection doses of rituximab 600 mg on days 1, 7, and 15. After the rituximab administration, he clinically recovered with multi-organ lesions disappeared. We plan to repeat endoscopic surveillance in 1 year.

…