Early anal gland adenocarcinoma with a characteristic submucosal tumor-like appearance: a case report

BACKGROUND: The clinical findings of early anal gland carcinoma (AGC) have not been well delineated because AGC is a rare malignancy usually diagnosed at an advanced stage. Knowledge of the characteristic findings will be helpful for both diagnosis and determination of the treatment options for early AGC. CASE PRESENTATION: A 62-year-old man was referred to our hospital for treatment of a rectal submucosal tumor (SMT) detected during a medical checkup at another hospital. Trans-sacral resection of the tumor was performed under the diagnosis of a rectal benign cyst. Pathological examination of the resected tumor showed a mucin-producing adenoma. About 14 months later, a new cystic lesion was found by follow-up examination, and trans-sacral resection of the tumor was performed again. The second pathological diagnosis was a mucinous adenocarcinoma with a possible remnant tumor at the local site. After providing sufficient informed consent, the patient underwent intersphincteric resection (ISR) of the rectum to preserve anal function. The final diagnosis was mucinous adenocarcinoma of the anal gland, T1N0M0. The patient remained alive without recurrence or complications for 6 years 7 months postoperatively. CONCLUSION: We have herein reported a case of early AGC with a characteristic SMT-like appearance. Because the anal gland is located within both the submucosal layer and the internal sphincter muscle, ISR may be selected when the tumor is limited to inside the gland.