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case_images: (A, B) Computed tomography images of the patient before surgery (2018-11). Enhanced CT scans of the abdomen revealed the dilatation and gas-fluid level of the colon. (C) Electronic colonoscopy prompts a large cauliflower lump in the colon, situated approximately 70cm from the anal verge. The lesion completely occluded the colon lumen.
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case_images: Enhanced computed tomography (CT) of the abdomen revealed colon dilatation, hydrops, and gas-fluid level, considering the possibility of bowel obstruction ( Figures 1A, B ). An electronic colonoscopy revealed a large cauliflower lump in the colon, situated approximately 70 cm from the anal verge ( Figure 1C ).
case_images: Haematoxylin-eosin staining (H&E) and IHC staining of the colon cancer tissue specimens. (A) The colon biopsy result is low differentiated adenocarcinoma, partially mucinous adenocarcinoma. (B) The tumour infiltrates the whole intestinal wall into extraneous fibrous adipose tissue.
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case_images: Postoperative pathology showed a poorly differentiated adenocarcinoma in the sigmoid flexure (pT4aN2M0,  Figure 2A ). Immunohistochemistry (IHC) results were as follows ( Figure 2B ): microsatellite stable/mismatch repair-proficient (MSS/pMMR), MLH1 (+), MSH2 (+), MSH6 (+), PSM2 (+), KI67 (60%), CDX2 (+), ER (-), and Vimentin (-).
case_images: Imaging in the palliative care process CT revealed metastatic lesions. (A) Colonoscopy found no abnormal changes (2020-08). (B) Imaging examinations performed more than 2 years after surgery (2021-02). Multiple metastatic lesions in the liver. (C) The PD-L1 IHC suggested the PD-L1 expression was 2%. (D) After four cycles of FOLFIRI plus cetuximab treatment, CT scans revealed significant enlargement of liver metastasis (2021-04). (E) MRI scans after five cycles of FOLFIRI plus bevacizumab showed the new abnormal high density shadow of the right skull, considering metastasis (2021-06). (F, G) After two months of the therapy of mFOLFOX6 and palliative radiation, hepatic metastatic lesions on CT were similar to the previous, the cranial MRI suggested cerebellar metastasis (2021-09). (H) The patient's last CT reexamination showed liver metastasis progressed again (2021-12).
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case_images: The last colonoscopy was performed in August 2020, with no anomaly either ( Figure 3A ). Until February 2021, the re-examination of the abdomen CT suggested multiple hepatic metastases, and the adrenal glands also metastasize, accompanied by the retroperitoneal lymph nodes enlargement ( Figure 3B ). The PD-L1 expression was 2% (CPS,  Figure 3C ). Therefore, cetuximab (800 mg) was added to the treatment regimen. After four cycles, since the enlargement of liver metastases, radiological evaluation demonstrated PD ( Figure 3D ) according to the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. April 2021. At the time of evaluation after five sessions, magnetic resonance imaging (MRI) showed new metastatic lesions in the skull ( Figure 3E ). Two months later, liver metastasis did not seem to increase significantly, while the follow-up MRI imaging presented cerebellar metastatic lesions ( Figures 3F, G ). On 21 December 2021, the patient had an abdominal CT performed at our hospital for the last time, and the liver lesion was enlarged again ( Figure 3H ).
case_images: Timeline of the disease evolution. XELOX, chemotherapy regimen containing capecitabine and oxaliplatin; FOLFIRI, chemotherapy regimen containing irinotecan, leucovorin and 5-FU; mFOLFOX6, chemotherapy regimen containing oxaliplatin, leucovorin and 5-FU. CT, computed tomography; MRI, magnetic resonance imaging; PD, progressive disease.
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case_images: After that, she never returned to the hospital.  Figure 4  shows the treatment administration of the patient.