Tumors and Tumorlike Conditions of the Anal Canal and Perianal Region: MR Imaging Findings.
Tumors and tumorlike conditions of the anus and perianal region originate from the anal canal and anal margin or result from direct extension of tumors from adjacent organs. The anatomy of the anal canal is complex, and its different histologic characteristics can lead to diverse pathologic conditions. The anal canal extends from the anorectal junction to the anal verge. The World Health Organization classification of anal canal tumors includes (a) anal intraepithelial neoplasia, the precursor of squamous cell carcinoma (SCC), and (b) invasive tumors. Invasive tumors are further classified on the basis of cell type as epithelial tumors (SCC, adenocarcinoma, mucinous adenocarcinoma, small cell carcinoma, and undifferentiated carcinoma), nonepithelial tumors, carcinoid tumors, melanoma, and secondary tumors (direct spread from rectal, cervical, or prostate carcinoma). The anal margin, or perianal skin, lies outside the anal verge and encompasses a radius of 5 cm from the anal verge. Tumors in the anal margin are classified according to the World Health Organization classification of skin tumors. Anal margin tumors include SCC, anal intraepithelial neoplasia, also known as Bowen disease, adenocarcinoma and its precursor Paget disease, basal cell carcinoma, and verrucous carcinoma (Buschke-Löwenstein tumor), which is a rare variant of SCC. Imaging plays an important role in the evaluation, staging, and follow-up of patients with anal and perianal tumors. However, because of the overlap in imaging features among these diverse entities, a definitive diagnosis is best established at histopathologic examination. Nevertheless, familiarity with the pathogenesis, imaging features, and treatment of these tumors can aid radiologic diagnosis and guide appropriate patient treatment. (©)RSNA, 2016.
From the Department of Radiology, University of Texas Health Science Center, 6431 Fannin St, MSB 2.130, Houston, TX 77030 (V.R.S.); Department of Radiology, Mayo Clinic, Scottsdale, Ariz (C.O.M., A.K.H.); Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, Tex (A.M.A., M.E., K.M.E.); Department of Radiology, University of Texas Health Science Center, San Antonio, Tex (V.S.K.); Department of Radiology, MetroHealth Medical Center, Cleveland, Ohio (W.C.B.); Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada (A.K.); and Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.L.S.).
Venkateswar R
VR
Surabhi
From the Department of Radiology, University of Texas Health Science Center, 6431 Fannin St, MSB 2.130, Houston, TX 77030 (V.R.S.); Department of Radiology, Mayo Clinic, Scottsdale, Ariz (C.O.M., A.K.H.); Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, Tex (A.M.A., M.E., K.M.E.); Department of Radiology, University of Texas Health Science Center, San Antonio, Tex (V.S.K.); Department of Radiology, MetroHealth Medical Center, Cleveland, Ohio (W.C.B.); Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada (A.K.); and Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.L.S.).
Christine O
CO
Menias
From the Department of Radiology, University of Texas Health Science Center, 6431 Fannin St, MSB 2.130, Houston, TX 77030 (V.R.S.); Department of Radiology, Mayo Clinic, Scottsdale, Ariz (C.O.M., A.K.H.); Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, Tex (A.M.A., M.E., K.M.E.); Department of Radiology, University of Texas Health Science Center, San Antonio, Tex (V.S.K.); Department of Radiology, MetroHealth Medical Center, Cleveland, Ohio (W.C.B.); Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada (A.K.); and Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.L.S.).
Ahmed M
AM
Amer
From the Department of Radiology, University of Texas Health Science Center, 6431 Fannin St, MSB 2.130, Houston, TX 77030 (V.R.S.); Department of Radiology, Mayo Clinic, Scottsdale, Ariz (C.O.M., A.K.H.); Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, Tex (A.M.A., M.E., K.M.E.); Department of Radiology, University of Texas Health Science Center, San Antonio, Tex (V.S.K.); Department of Radiology, MetroHealth Medical Center, Cleveland, Ohio (W.C.B.); Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada (A.K.); and Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.L.S.).
Mohamed
M
Elshikh
From the Department of Radiology, University of Texas Health Science Center, 6431 Fannin St, MSB 2.130, Houston, TX 77030 (V.R.S.); Department of Radiology, Mayo Clinic, Scottsdale, Ariz (C.O.M., A.K.H.); Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, Tex (A.M.A., M.E., K.M.E.); Department of Radiology, University of Texas Health Science Center, San Antonio, Tex (V.S.K.); Department of Radiology, MetroHealth Medical Center, Cleveland, Ohio (W.C.B.); Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada (A.K.); and Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.L.S.).
Venkata S
VS
Katabathina
From the Department of Radiology, University of Texas Health Science Center, 6431 Fannin St, MSB 2.130, Houston, TX 77030 (V.R.S.); Department of Radiology, Mayo Clinic, Scottsdale, Ariz (C.O.M., A.K.H.); Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, Tex (A.M.A., M.E., K.M.E.); Department of Radiology, University of Texas Health Science Center, San Antonio, Tex (V.S.K.); Department of Radiology, MetroHealth Medical Center, Cleveland, Ohio (W.C.B.); Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada (A.K.); and Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.L.S.).
Amy K
AK
Hara
From the Department of Radiology, University of Texas Health Science Center, 6431 Fannin St, MSB 2.130, Houston, TX 77030 (V.R.S.); Department of Radiology, Mayo Clinic, Scottsdale, Ariz (C.O.M., A.K.H.); Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, Tex (A.M.A., M.E., K.M.E.); Department of Radiology, University of Texas Health Science Center, San Antonio, Tex (V.S.K.); Department of Radiology, MetroHealth Medical Center, Cleveland, Ohio (W.C.B.); Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada (A.K.); and Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.L.S.).
William C
WC
Baughman
From the Department of Radiology, University of Texas Health Science Center, 6431 Fannin St, MSB 2.130, Houston, TX 77030 (V.R.S.); Department of Radiology, Mayo Clinic, Scottsdale, Ariz (C.O.M., A.K.H.); Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, Tex (A.M.A., M.E., K.M.E.); Department of Radiology, University of Texas Health Science Center, San Antonio, Tex (V.S.K.); Department of Radiology, MetroHealth Medical Center, Cleveland, Ohio (W.C.B.); Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada (A.K.); and Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.L.S.).
Ania
A
Kielar
From the Department of Radiology, University of Texas Health Science Center, 6431 Fannin St, MSB 2.130, Houston, TX 77030 (V.R.S.); Department of Radiology, Mayo Clinic, Scottsdale, Ariz (C.O.M., A.K.H.); Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, Tex (A.M.A., M.E., K.M.E.); Department of Radiology, University of Texas Health Science Center, San Antonio, Tex (V.S.K.); Department of Radiology, MetroHealth Medical Center, Cleveland, Ohio (W.C.B.); Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada (A.K.); and Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.L.S.).
Khaled M
KM
Elsayes
From the Department of Radiology, University of Texas Health Science Center, 6431 Fannin St, MSB 2.130, Houston, TX 77030 (V.R.S.); Department of Radiology, Mayo Clinic, Scottsdale, Ariz (C.O.M., A.K.H.); Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, Tex (A.M.A., M.E., K.M.E.); Department of Radiology, University of Texas Health Science Center, San Antonio, Tex (V.S.K.); Department of Radiology, MetroHealth Medical Center, Cleveland, Ohio (W.C.B.); Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada (A.K.); and Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (C.L.S.).
Cary L
CL
Siegel
D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000473:pathology; D001003:Anal Canal / Q000000981:diagnostic imaging* / Q000473:pathology*; D001005:Anus Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D002278:Carcinoma in Situ / Q000000981:diagnostic imaging / Q000473:pathology; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000473:pathology; D003937:Diagnosis, Differential; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*