Background: Alpha-fetoprotein (AFP)-producing rectal cancer is very rare, and this type of cancer frequently metastasizes to the liver with a poor prognosis. To date, only 11 cases of AFP-producing colorectal cancer have been reported.
Case presentation: A 41-year-old woman was first presented to the hospital for anal bleeding. An elevated tumor with a central shallow depression in the lower rectum was detected by colonoscopy. Transanal excision was performed, and the histology revealed adenocarcinoma. Further immunohistopathological examination revealed that the tumor was an AFP-producing adenocarcinoma of the rectum. Although local resection was performed 2 months before the diagnosis of AFP tumor, the serum AFP level was normal. The depth of the submucosal invasion was 5,000 μm, and there was venous invasion. Also, no lymphatic invasion was detected. Therefore, additional surgical resection with lymph node dissection was conducted, and the patient underwent laparoscopic intersphincteric resection. No residual cancer was identified in the surgical specimens, and there was no evidence of lymph node metastasis. The patient was discharged 18 days postoperatively, and 12 months after the operation, there are no signs of recurrence.
Conclusion: To the best of our knowledge, this is the first case of an AFP-producing rectal cancer that was diagnosed at an early stage.