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case_images: Abdominal CT on admission. Abdominal CT shows a huge, 18-cm mass in the right upper abdomen (Fig. 1). The tumor is located very close to surrounding organs such as the duodenum (arrow) and right kidney (arrow head).
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case_images: Abdominal computed tomography showed a huge 18-cm mass in the right upper abdomen (Fig. 1).
case_images: Colonoscopy findings. Colonoscopy shows a circumferential type 2 tumor at the transverse colon. The scope cannot pass through to the oral side of the tumor.
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case_images: Colonoscopy showed a circumferential type 2 tumor located at the transverse colon (Fig. 2).
case_images: Histology of the biopsy specimen. HE stains show poorly differentiated adenocarcinoma with atypical epithelial cells that have proliferated solidly with focal glandular structure, and many apoptotic cells and mitotic figures.
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case_images: Biopsy showed poorly differentiated adenocarcinoma (Fig. 3); RAS status was mutant.
case_images: Abdominal CT after 6 courses of neoadjuvant chemotherapy. After 6 courses of treatment, the primary tumor has shrunk remarkably to 5.0 cm. Invasion to surrounding organs is not observed.
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case_images: After 6 courses of treatment, the primary tumor had shrunk remarkably, from 18.0 cm to 5.0 cm (Fig. 4), and invasion to surrounding organs was not observed.
case_images: Gross appearance of the cut surface. The yellow-whitish area indicates degenerative change of the carcinoma due to neoadjuvant chemotherapy (a). Histology of the degenerative cancer area. Foamy macrophages and psammomatous bodies without viable cancer cells are seen (b).
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case_images: Macroscopic examination showed a 4.8cm x 4.1cm tumor at the transverse colon (Fig. 5a). Histopathologically, the primary tumor and enlarged lymph nodes consisted of fibrous or granuloma-like tissues, and no residual cancer cells were found (pCR) (Fig. 5b).