Abstract
Background: Medullary carcinoma of the colon, formerly classified as poorly differentiated adenocarcinoma, was classified as a special type as a new concept in the 8th edition of the Japanese Code of Treatment of Colorectal Cancer, revised in July 2013. The prognosis is relatively good, with a high degree of microsatellite instability and a predilection for the right-sided colon.
Case presentation: A 90-year-old woman was referred to our hospital for a semi-peripheral type 2 tumor that was found in the ascending colon after a lower gastrointestinal endoscopy was performed by a local doctor to investigate slowly progressive anemia. Histopathological examination of the biopsy specimen revealed adenocarcinoma. Contrast-enhanced computed tomography of the thorax and abdomen showed irregular wall thickening and contrast effect in the ileocecal region, with no obvious extramural extension, enlarged lymph nodes, or distant metastasis. She underwent laparoscopic ileal resection + D3 dissection for cT2N0M0 cStage I ascending colon cancer. The postoperative course was good, and the patient was discharged on postoperative day 11. Postoperative histopathological examination revealed a well-defined, enlarged nucleolus within a large, stained nucleus, hyperplastic linear epithelium with acidophilic cytoplasm, and numerous tumor-infiltrating lymphocytes, leading to a diagnosis of colorectal medullary carcinoma pT3N0M0 pStage IIa. The patient is currently alive and recurrence-free 1 year after surgery.
Conclusion: We report a rare case of resection of medullary carcinoma of the colon arising in the ascending colon. The histology has a characteristic clinical presentation and prognosis, requiring appropriate diagnosis and follow-up.
