PMC9807352_01
Computed tomography (CT) images of the abdominal wall mass suspected to be a urachal carcinoma. (a) Axial CT image of the abdominal wall mass (arrowheads). (b) Sagittal CT image showing an abdominal wall mass (arrowhead) connected to the urachus. (c) Axial and (d) coronal 18F-fluorodeoxyglucose positron emission tomography images of the abdominal wall mass (arrowheads).
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Computed tomography (CT) revealed a well-enhanced mass in the lower umbilical area involving the rectus abdominis muscle (Fig. 1a,b) and showed high uptake (SUV max = 16.49) on 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) CT (Fig. 1c,d), suggesting malignancy.
Magnetic resonance images of the abdominal wall mass suspected to be a urachal carcinoma. (a) Axial T2-weighted and (b) axial diffusion-weighted images of the abdominal wall mass. Median ADC value within the tumor was 1.16 x 103 mm2/sec. (c) Sagittal T2-weighted image revealing the mass (arrowheads) connected to the urachus (arrow). (d) Sagittal T2-weighted image showing the mass (arrowheads) invading the small intestine (arrow).
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Magnetic resonance imaging (MRI) revealed that the mass was isointense on T2-weighted imaging (Fig. 2a) and hyperintense on diffusion-weighted imaging (Fig. 2b). Furthermore, the mass was connected to the restiform structure, which was supposed to be the urachus (Fig. 2c). The mass had an irregular medial surface and was connected to the small intestines; this arrangement was suspected to be an invasion of the greater omentum and small intestine (Fig. 2d).
Microscopic findings of the resected tumor. (a) A loupe image (x4) of the border between the abdominal wall tumor (right) and ileum (left). The ileal mucosa is observed in the area within the black dotted square, which is enlarged in the right panel (b). (B) Histopathological findings (x200) of the ileal mucosa at the margin between the tumor and the ileum. The ileal mucosa (arrowheads) protruded out of the ileal wall without an accompanying muscularis propria, suggesting that this area was a pseudodiverticulum. The pseudodiverticulum connected to the abscess that had extensive neutrophil infiltration.
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On pathological evaluation, the ileal mucosa was observed at the border between the tumor and the ileum (Fig. 3a) and protruded without an accompanying muscularis propria; thus, the structure was considered as a pseudodiverticulum. Additionally, this pseudodiverticulum had been infiltrated by neutrophils and formed an abscess (Fig. 3b).