PMC6755283_01
Computed tomography imaging at different stages. (a) Presurgical CT scan: infiltrative mass of the ascending colon causing significant mural thickening and luminal narrowing, associated with minimal surrounding free fluid and peritoneal nodularities. (b) Postsurgical CT scan: minimal residual nodularities at the site of surgery which can represent peritoneal deposits. (c) Postchemotherapy completion CT scan: further decrease and almost complete resolution of the peritoneal nodularities.
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An abdominal CT scan revealed significant and irregular circumferential thickening of the ascending colon wall that suggests intussusception (Figure 2(a)). Three months later, a CT scan of the abdomen demonstrated minimal omental thickening and stranding with minimal residual nodularities (Figure 2(b)). CT scan showed resolution of the peritoneal nodularities (Figure 2(c)). Chemotherapy treatment was arrested after considering the patient's status, prognosis, and risk of recurrence.
Invasive poorly differentiated carcinoma. (a) Invasive colonic signet ring carcinoma with extracellular mucin pools (200x). (b) Signet ring morphology, higher magnification (400x). (c) Signet ring tumor cells infiltrating into pericolonic fat (400x).
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IV (T4a N0 M1, with peritoneal seeding) (Figure 3). Immunohistochemistry for MLH1, MSH2, MSH6, and PMS2 showed the absence of mutations for microsatellite instability (Figure 4).
Immunohistochemistry testing for mismatch repair proteins. All proteins show intact nuclear expression: (a) MLH1, (b) MSH2, (c) MSH6, and (d) PMS2.
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IV (T4a N0 M1, with peritoneal seeding) (Figure 3). Immunohistochemistry for MLH1, MSH2, MSH6, and PMS2 showed the absence of mutations for microsatellite instability (Figure 4).