Infiltrating adenocarcinoma arising in a villous adenoma of the anal canal

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.

Metachronous tubulovillous and tubular adenomas of the anal canal

Anal canal adenoma is an extremely rare disease that has the potential to transform into a malignant tumor. We herein presented a rare case of metachronous multiple adenomas of the anal canal. A 48-year-old woman underwent total colonoscopy following a positive fecal blood test. A 9-mm villous polyp arising from the posterior wall of the anal canal was removed by snare polypectomy. Histologically, the tumor was tubulovillous adenoma with high-grade dysplasia and the cut end was negative for tumor cells. Six years later, an elevated lesion, macroscopically five millimeters in size, was detected in the left wall of the anal canal in a follow-up colonoscopy. Local excision of the tumor was performed, and the lesion was pathologically confirmed to be tubular adenoma with high-grade dysplasia limited to the mucosa. The patient is currently alive without any evidence of recurrence for six months after surgery. Although she had a past history of cervical cancer, the multiple tumors arising in the anal canal were unlikely to be related to human papilloma virus infection. Our case report underscores the importance of careful observations throughout colonoscopy to detect precancerous lesions, particularly in anatomically narrow segments.

Neoplasms of anal canal and perianal skin

Tumors of the anus and perianal skin are rare. Their presentation can vary and often mimics common benign anal pathology, thereby delaying diagnosis and appropriate and timely treatment. The anatomy of this region is complex because it represents the progressive transition from the digestive system to the skin with many different co-existing types of cells and tissues. Squamous cell carcinoma of the anal canal is the most frequent tumor found in the anal and perianal region. Less-frequent lesions include Bowen's and Paget's disease, basal cell carcinoma, melanoma, and adenocarcinoma. This article aims to review the clinical presentation, diagnostic evaluation, and treatment options for neoplasms of the anal canal and perianal skin.

Invasive cancer in a diminutive rectal polyp amidst internal hemorrhoids detected by rectal retroflexion

A diminutive rectal polyp amidst internal hemorrhoids, detected by rectal retroflexion during colonoscopy, was shown to harbor invasive rectal adenocarcinoma by colonoscopic biopsy. Initially this lesion had appeared to be a relatively innocuous prominent anorectal mucosal fold and was recognized as a diminutive polyp only after careful rectal retroflexion during colonoscopy. This report emphasizes that lesions just above the anorectal junction with atypical endoscopic features for internal hemorrhoids should be carefully examined at rectal retroflexion and that polyps or suspicious lesions amidst internal hemorrhoids identified during colonoscopy should be snared or at least biopsied, even if small. This case report also illustrates how easily an early cancer in a diminutive colonic polyp can be missed when in difficult areas of colonoscopic inspection, such as behind a colonic fold or immediately above the anus.