A mucosa-associated lymphoid tissue (MALT) lymphoma of the small intestine that was difficult to diagnose endoscopically

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A 75-year-old man was admitted with bloating, distension, and diarrhea since the past 2 months. He was not taking nonsteroidal anti-inflammatory agents (NSAIDs) on a regular basis. Abdominal computed tomography (CT) revealed a stricture in the jejunum. A small-bowel contrast study showed a severe stricture in the jejunum, which was dilated on its proximal side. Upper gastrointestinal endoscopy revealed gastritis and Helicobacter pylori. A colonoscopy revealed no abnormal findings. Oral single-balloon enteroscopy revealed a stricture 120 cm distal to the pylorus. Irregularity of the small-bowel mucosa was observed but there was no ulceration ([Fig. 1]). Histological examination of a biopsy specimen revealed interstitial atypical lymphoid hyperplasia.

Two weeks later, the patient was still symptomatic and a second enteroscopy was carried out for another biopsy specimen; during this procedure, a shallow ulcer was observed on the proximal side of the stricture ([Fig. 2]). The biopsy revealed a lymphoepithelial lesion that was positive for CD20 and CD79a ([Fig. 3]) and negative for CD10 and CD5. On the basis of these findings, the patient was diagnosed as having marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT).

After antibiotic treatment for H. pylori eradication, the patient was treated with three cycles of rituximab and four cycles of rituximab plus R-CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone) chemotherapy. A third enteroscopy showed that the ulcer had healed and the stricture had reduced in size ([Fig. 4]).

In the present case, a change in the form of the lesion was observed within a short time period, because of which a pathological diagnosis was possible. Although enteroscopy is widely used for detection and diagnosis, the procedure should be done more than once to obtain a reliable diagnosis.

Fig. 1 The first enteroscopy showing a stricture 120 cm distal to the pylorus. There is irregularity of the small-bowel mucosa, but with no ulceration.

Fig. 2 The second enteroscopy showing a shallow ulcer on the proximal side of the stricture.

Fig. 3 a Histological section showing interstitial atypical lymphoid hyperplasia and lymphoepithelial lesions. The cells were positive for b CD20 and c CD79a.

Fig. 4 The third enteroscopy carried out after chemotherapy showing absence of ulceration and reduced stricture.

Endoscopy_UCTN_Code_CCL_1AC_2AC