A case of metastatic carcinoma of anal fistula caused by implantation from rectal cancer

Abstract

This case involved an 80-year-old man who was seen for melena. Further testing revealed a tubular adenocarcinoma 50 mm in size in the rectum. In addition, an anal fistula was noted behind the anus along with induration. A biopsy of tissue from the external (secondary) opening of the fistula also revealed adenocarcinoma. Nodules suspected of being metastases were noted in both lung fields. The patient was diagnosed with rectal cancer, a cancer arising from an anal fistula, and a metastatic pulmonary tumor, and neoadjuvant chemotherapy was begun. A laparoscopic abdominoperineal resection was performed 34 days after 6 cycles of mFOLFOX-6 therapy. Based on pathology, the rectal cancer was diagnosed as moderately differentiated adenocarcinoma, and this adenocarcinoma had lymph node metastasis (yp T3N2aM1b). There was no communication between the rectal lesion and the anal fistula, and a moderately differentiated tubular adenocarcinoma resembling the rectal lesion was noted in the anal fistula. Immunohistochemical staining indicated that both the rectal lesion and anal fistula were cytokeratin 7 (CK7) (−) and cytokeratin 20 (CK20) (+), and the patient’s condition was diagnosed as implantation of rectal cancer in an anal fistula.In instances where an anal fistula develops in colon cancer, cancer implantation in that fistula must also be taken into account, and further testing should be performed prior to surgery.

Synchronous Sigmoid Colon Cancer Seeding a Fistula-in-Ano

“…We describe a case where synchronous sigmoid colon cancer seeded a fistula-in-ano. Although rare, other case reports have also concluded this when implanted cells in the fistula share the same histology as the primary cancer from the sigmoid or rectum [ 1 ]. This includes the presence of mucinous material, as noted in our case [ 4 ].…”

“…A seeded fistula-in-ano from a synchronous adenocarcinoma of the colon or rectum is rare. Till date, only 28 cases have been reported since the report by Guiss, et al in 1954 [ 1 - 3 ]. Given its rarity and often late presentation of symptoms (typically attributed to perineal disease), a low suspicion to biopsy a fistula-in-ano has been advocated [ 4 ].…”

Rectosigmoid Adenocarcinoma That Is Synchronous with an Anal Fistula : Case Report in Saudi Arabia

“…We present a case that has rarely been reported in Arab countries. A chronic anal fistula that presents repeatedly with perianal abscess that later was found to be synchronous with rectosigmoid mucinous adenocarcinoma treated with extralevator abdominoperineal resection (1) . An anal fistula that is persistent and recurrent causes inflammation that can lead to primary cancer, in 0,1% of all anal fistulae cancer will develop (1,2) .…”

“…A chronic anal fistula that presents repeatedly with perianal abscess that later was found to be synchronous with rectosigmoid mucinous adenocarcinoma treated with extralevator abdominoperineal resection (1) . An anal fistula that is persistent and recurrent causes inflammation that can lead to primary cancer, in 0,1% of all anal fistulae cancer will develop (1,2) . This case emphasizes the importance of further investigation of recurrent perianal abscesses and the need for biopsy of anal fistula (3) .…”

Rectal Cancer Metastasis to an Anal Fissure

“…A large number of colonic epithelial cells are exfoliated daily from the gut and, growth factors from open wound or ulcerated mucosa allows tumor implantation and growth [6]. The diagnosis of anal metastasis is suggested when both proximal bowel and anal cancer have the same histopathological features [7].…”