A 75-year-old woman presented with a positive fecal occult blood test. She had no previous personal or family history of malignancy. Colonoscopy revealed a slightly yellowish 6-mm protrusion in the rectum resembling a submucosal tumor (SMT) (Fig. 1A). Narrow-band imaging showed dilated vessels with branching architectures on the surface and a nonstructural area (Fig. 1B), suggestive of mucosa-associated lymphoid tissue (MALT) lymphoma. However, the color of the lesion was indicative of a carcinoid tumor, which was therefore suspected. Owing to the overlapping features of MALT lymphoma and carcinoid tumor, optical diagnosis of the SMT-like protrusion would be of low confidence. Therefore, it was removed by endoscopic submucosal resection with band ligation (ESMR-L) for diagnosis and treatment (Fig. 1C). Histopathologic examination showed diffuse infiltration of monotonous small-sized lymphoid cells in the mucosa (Fig. 2), positive for CD20 but negative for CD3 and CD10. The lesion was diagnosed as rectal MALT lymphoma. The resected margin was negative. The patient recovered with no complications and remains in complete remission at the five-year follow up.
Figure 1 (A) Colonoscopy showed a slightly yellowish, 6-mm submucosal tumor-like protrusion in the rectum. (B) Narrow-band imaging showed dilated vessels with branching architectures on the surface and a nonstructural area. (C) The lesion was removed by endoscopic submucosal resection with band ligation
Figure 2 Histopathologic examination revealed a mucosa-associated lymphoid tissue lymphoma
Whereas ESMR-L is widely used for the treatment of carcinoid tumors , our result demonstrates that the technique can also be used for the precise evaluation and safe treatment of a localized, small MALT lymphoma. For an SMT-like protrusion, endoscopic treatment requires special techniques for deeper resection, such as ESMR-L, to achieve clear margins . In the case of a single small SMT-like protrusion in the rectum with low-confidence diagnosis, the lesion should be removed by ESMR-L and sent for precise assessment, difficult with biopsy and endoscopic ultrasound.