title: Primary malignant melanoma of the rectum: CT findings in eight patients.
abstract: OBJECTIVE
  To retrospectively evaluate computed tomographic (CT) findings in patients with pathologically proved primary malignant melanoma of the rectum.
  
  
  METHODS
  CT scans of eight patients (three men and five women; age range, 38-74 years; mean age, 62 years) with histologically proved primary rectal malignant melanomas were retrospectively evaluated by two radiologists in consensus. Scans were evaluated for the involved site, approximate size and morphologic appearance of the primary mass, degree of perirectal infiltration, and presence or absence of lymphadenopathy, bowel obstruction, and distant metastases.
  
  
  RESULTS
  All of the tumors were located in the distal rectum just above the anal verge. The approximate average sizes of the tumors were as follows: length, 4.8 cm (range, 3.8-6.9 cm); width, 3.8 cm (range, 2.8-5.2 cm); and mean diameter, 4.3 cm (range, 3.3-5.8 cm). Tumors usually appeared as polypoid or fungating intraluminal masses (n = 7). Perirectal infiltration commonly extended to the pelvic side wall or the presacral space (n = 5). All eight patients had lymphadenopathy, frequently larger than 3 cm in diameter (n = 3), which most commonly involved the perirectal lymph node station (n = 7). There was no evidence of bowel obstruction in any of the patients. Distant metastasis involving the liver was noted in one patient.
  
  
  CONCLUSIONS
  On CT scans, primary rectal malignant melanomas appeared as bulky intraluminal fungating masses in the distal rectum, focally expanding and obscuring the lumen without causing obstruction, with perirectal infiltration and frequently enlarged lymph nodes.
authors.affiliation: Departments of Radiology, Pathology, and Surgery, Asan Medical Center, University of Ulsan College of Medicine, 388-1 Poongnap-dong, Songpa-ku, Seoul 138-736, Korea.
authors.forename: Kyoung Won
authors.initials: KW
authors.lastname: Kim
authors.forename: Hyun Kwon
authors.initials: HK
authors.lastname: Ha
authors.forename: Ah Young
authors.initials: AY
authors.lastname: Kim
authors.forename: Tae Kyoung
authors.initials: TK
authors.lastname: Kim
authors.forename: Jung-Sun
authors.initials: JS
authors.lastname: Kim
authors.forename: Chang Sik
authors.initials: CS
authors.lastname: Yu
authors.forename: Sung Won
authors.initials: SW
authors.lastname: Park
authors.forename: Mi-Suk
authors.initials: MS
authors.lastname: Park
authors.forename: Hye Jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Pyo-Nyun
authors.initials: PN
authors.lastname: Kim
authors.forename: Jin Cheon
authors.initials: JC
authors.lastname: Kim
authors.forename: Moon-Gyu
authors.initials: MG
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008545:Melanoma / Q000000981:diagnostic imaging* / Q000473:pathology; D008875:Middle Aged; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D014057:Tomography, X-Ray Computed