title: Metachronous tubulovillous and tubular adenomas of the anal canal.
abstract: 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.
authors.affiliation: Department of Surgical Oncology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. hiroanozawa-gi@umin.ac.jp.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nozawa
authors.affiliation: Department of Surgical Oncology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. ishihara-1su@h.u-tokyo.ac.jp.
authors.forename: Soichiro
authors.initials: S
authors.lastname: Ishihara
authors.affiliation: Department of Pathology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. morikawat-pat@h.u-tokyo.ac.jp.
authors.forename: Teppei
authors.initials: T
authors.lastname: Morikawa
authors.affiliation: Department of Surgical Oncology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. tanakaj-sur@h.u-tokyo.ac.jp.
authors.forename: Junichiro
authors.initials: J
authors.lastname: Tanaka
authors.affiliation: Department of Surgical Oncology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. yasudak-sur@h.u-tokyo.ac.jp.
authors.forename: Koji
authors.initials: K
authors.lastname: Yasuda
authors.affiliation: Department of Surgical Oncology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. otanik-sur@h.u-tokyo.ac.jp.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Ohtani
authors.affiliation: Department of Surgical Oncology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. nishikawata-sur@h.u-tokyo.ac.jp.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nishikawa
authors.affiliation: Department of Surgical Oncology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. tanakat-sur@h.u-tokyo.ac.jp.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Department of Surgical Oncology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. kiyomatsut-sur@h.u-tokyo.ac.jp.
authors.forename: Tomomichi
authors.initials: T
authors.lastname: Kiyomatsu
authors.affiliation: Department of Surgical Oncology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. kawaik-sur@h.u-tokyo.ac.jp.
authors.forename: Kazushige
authors.initials: K
authors.lastname: Kawai
authors.affiliation: Department of Surgical Oncology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. hatak-sur@h.u-tokyo.ac.jp.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Hata
authors.affiliation: Department of Surgical Oncology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. kazamas-sur@h.u-tokyo.ac.jp.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Kazama
authors.affiliation: Department of Surgical Oncology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. yamaguchih-sur@h.u-tokyo.ac.jp.
authors.forename: Hironori
authors.initials: H
authors.lastname: Yamaguchi
authors.affiliation: Department of Surgical Oncology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. sunami-1su@h.u-tokyo.ac.jp.
authors.forename: Eiji
authors.initials: E
authors.lastname: Sunami
authors.affiliation: Department of Surgical Oncology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. kitayama-1su@h.u-tokyo.ac.jp.
authors.forename: Joji
authors.initials: J
authors.lastname: Kitayama
authors.affiliation: Department of Pathology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. fukayamam-pat@h.u-tokyo.ac.jp.
authors.forename: Masashi
authors.initials: M
authors.lastname: Fukayama
authors.affiliation: Department of Surgical Oncology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. watanabe-1su@h.u-tokyo.ac.jp.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Watanabe
mesh_terms: D000236:Adenoma / Q000473:pathology*; D001005:Anus Neoplasms / Q000473:pathology*; D002294:Carcinoma, Squamous Cell / Q000453:epidemiology; D015897:Comorbidity; D005260:Female; D006801:Humans; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology*; D016609:Neoplasms, Second Primary / Q000453:epidemiology / Q000473:pathology; D002583:Uterine Cervical Neoplasms / Q000453:epidemiology