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Lee and Kang: A focally flat-elevated lesion in distal transverse colon resembling a subepithelial tumor


A 72-year-old male with intermittent left upper quadrant pain was admitted to our hospital with an abnormal lesion in the distal transverse colon detected by abdominopelvic computed tomography (APCT) at a local clinic. He had undergone a surveillance colonoscopy one year previously. At that time, his colonoscopy finding was completely normal. Physical examination of the abdomen revealed mild tenderness on the left upper quadrant of the abdomen. The complete blood count and blood chemistry results were normal. However, the carcinoembryonic antigen was 4.8 ng/mL, which was slightly elevated compared to the reference range (0–3.5 ng/mL).
APCT revealed focal thickening of the distal transverse colon, with enlarged pericolic lymph nodes (Fig. 1). Colonoscopy and narrow-band imaging (NBI) revealed a focally elevated lesion in the distal transverse colon resembling a subepithelial tumor (Fig. 2). Biopsies were performed, and pathological findings with hematoxylin and eosin and immunohistochemical (IHC) staining for CD20, CD3 and Ki-67 are as follows (Fig. 3). What was the most likely diagnosis?


Conflicts of Interest
Sang-Bum Kang is currently serving as a KSGE Publication Committee member; however, he had not involved in the peer reviewer selection, evaluation, or decision process of this article. Shin-Hee Lee has no potential conflicts of interest.
The patient provided informed consent and agreed to publication of the images.
Author Contributions
Conceptualization: SBK; Data curation: SHL, SBK; Supervision: SBK; Writing–original draft: SHL, SBK; Writing–review & editing: SBK.

Fig. 1.
Abdominopelvic computed tomography with axial view (A) and coronal view (B) revealed wall thickening of the distal transverse colon (white arrows) and infiltration along the mesentery around the distal transverse colon.
Fig. 2.
Colonoscopy. A flat, elevated lesion was observed in the distal transverse colon on colonoscopy (A), and an abnormal vasculature was observed on narrow-band imaging (B).
Fig. 3.
Histological findings. (A) Atypical lymphoid cell proliferation was seen in the deep mucosa and submucosa, and many lymphoepithelial lesions were observed (hematoxylin and eosin stain, ×100). (B, C) Lymphoid cells was positive for CD20 and negative for CD3 (immunohistochemical stain, x100). (D) Ki-67 labeling index was 7% (Ki-67 stain, x200).


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