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case_images: The longitudinal US of the supra-umbilical region (A) shows an anechoic cyst with multiple internal septa (short arrows), strongly demarcated by the intestinal wall structures (long arrows), suggestive of a cystic lesion located in the transverse colon. Color Doppler (B) demonstrated no hypervascularity of this multicellular cyst as well as of the colonic wall surrounding it.
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case_images: This lesion manifested as a multilocular anechoic cystic mass with internal septa of varying thickness, and no hypervascularity on echocardiography (Figure 1).
case_images: Abdominal CT with late venous phase, axial (A) and coronal (B) views of the transverse colon found fluid-attenuation density mass (10-12HU) with low enhanced septa ((A), arrow) measuring 42x47 x 63 mm. The mass is partially surrounded by air in the colon and this site revealed a very thin unenhanced wall ((B), short arrow). The colonic segment upstream to the mass is thick-walled with enhanced thin mucosa and without clear pericolonic fat stranding ((B), long arrow).
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case_images: An abdominal CT scan revealed a low-density multilocular mass, with a low contrast-enhanced wall and internal septa located in the transverse colon; the proximal transverse colon showed thickened submucosal edema (Figure 2).
case_images: Colonoscopic view (A and B) demonstrated a large smooth-surfaced sub-pedunculated polyp with glossy, pinkish mucosal coating located in the transverse colon presenting as a submucosal tumor.
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case_images: Flexible colonoscopy documented a broad-based smooth polypoid mass with glossy pinkish mucosal coating in the middle part of the transverse colon (Figure 3).
case_images: Gross morphology during surgery revealed a 4x6 cm, soft and spongy submucosal polypoid mass (arrow) in the transverse colon.
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case_images: Based on the diagnosis of submucosal tumor of the transverse colon, laparoscopic surgery with right hemicolectomy was performed, which showed a 4 x 6 cm, soft and spongy submucosal polypoid lesion on palpation, confined to intramural colon and non-invasion out of the serosa (Figure 4).
case_images: Photomicrograph of histopathologic specimen (HE stain). (A) (x20) showing the submucosal cystic lymphangioma with the interior wall lined by flattened endothelium (arrows). (B) (x40) showing a wall that has multiple dilated spaces (asterisks), lined by a thin layer of endothelial cells (short arrow); between these lymphatic spaces are smooth muscles and foci of lymphocyte clusters (long arrow).
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case_images: Histopathological examination revealed thin-walled dilated spaces consisting of only a single layer of endothelial cells (Figure 5).