PMC9285534_01
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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This lesion manifested as a multilocular anechoic cystic mass with internal septa of varying thickness, and no hypervascularity on echocardiography (Figure 1).
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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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).
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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Flexible colonoscopy documented a broad-based smooth polypoid mass with glossy pinkish mucosal coating in the middle part of the transverse colon (Figure 3).
Gross morphology during surgery revealed a 4x6 cm, soft and spongy submucosal polypoid mass (arrow) in the transverse colon.
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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).
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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Histopathological examination revealed thin-walled dilated spaces consisting of only a single layer of endothelial cells (Figure 5).