Anal Adenocarcinoma Can Masquerade as Chronic Anal Fistula in Asians

PURPOSE: Perianal adenocarcinoma arising from a chronic anorectal fistula is a rare condition for which the natural history and optimal management are not well established. For that reason, we conducted a retrospective analysis of 5 consecutive patients with a perianal adenocarcinoma arising from a chronic anorectal fistula managed at our institution from January 2014 to December 2015. METHODS: The patients were identified from a prospectively collected colorectal cancer database that included all patients managed for colorectal cancer at our institution. RESULTS: The median age at diagnosis was 64 years (range, 55–72 years). Magnetic resonance imaging (MRI) was the initial investigation for all patients and showed a hyperintense T2-weighted image. One patient underwent an abdominoperineal resection following neoadjuvant chemoradiotherapy and remained disease free during the 12-month follow-up. Three patients received neoadjuvant therapy with intent for surgery, but did not undergo surgery due to either worsening health or metastatic spread. One patient declined intervention. The median overall survival was 10.5 months (range, 2–19 months). CONCLUSION: A high index of suspicion is required to make a clinical diagnosis of an anal adenocarcinoma arising from a chronic fistula. Histologic diagnosis must be achieved to confirm the diagnosis. Multimodal therapy with neoadjuvant chemoradiotherapy followed by abdominoperineal resection is the treatment of choice.

Adenocarcinoma of the anal canal: A report of two cases with review of literature.

Adenocarcinoma of the anal canal accounts for about 20% of all anal canal cancers. It is subclassified into two types. (1) Colorectal type, which arises from the mucosa above dentate line and (2) extramucosal type, which includes adenocarcinoma arising in anorectal fistulae and adenocarcinoma arising from anal glands. Anal gland adenocarcinomas are extremely rare. In this article, we present two cases of anal adenocarcinoma, one colorectal type, and other anal gland carcinoma along with review of literature.