Squamous cell carcinoma of the anus and rectum in homosexual men: CT findings.
OBJECTIVE
Homosexual men are at risk for a variety of infectious and neoplastic diseases of the anus and rectum, many of which have been reported in the radiologic literature. The purpose of this study was to describe the CT findings in homosexual men with squamous cell carcinoma of the anus and rectum, a topic that has received little attention.


METHODS
Computed tomography examinations of the abdomen and pelvis of nine homosexual men with squamous cell carcinoma of the anus and rectum were reviewed retrospectively. Six HIV-positive men were 28-44 years old (average, 37 years). Three HIV-negative men were 47-61 years old (average, 54 years).


RESULTS
In six of the nine patients, CT showed a mass involving the anal canal. In five of these six patients, the tumor extended caudad to involve perianal fat and skin (one patient), cephalad to involve the rectum and perirectal fat (two patients), or both (two patients). In three of the nine patients, the anal canal did not appear to be involved by the tumor; CT showed circumferential rectal wall thickening (one patient), an excavated eccentric rectal tumor (one patient), or a cystic extramucosal rectal mass (one patient). Computed tomography evidence of noncontiguous metastasis was limited to inguinal and iliac lymph node enlargement in two of the nine patients.


CONCLUSIONS
Because CT findings are varied and nonspecific, squamous cell carcinoma should be included in the differential diagnosis of anorectal lesions in homosexual men.
Department of Radiology, University of Southern California School of Medicine, Los Angeles County-USC Medical Center 90033-1084.
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D000328:Adult; D001005:Anus Neoplasms / Q000000981:diagnostic imaging*; D001466:Barium Sulfate; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging*; D004733:Enema; D005500:Follow-Up Studies; D018023:HIV Seronegativity; D006679:HIV Seropositivity; D018451:Homosexuality, Male; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D012812:Sigmoidoscopy; D015996:Survival Rate; D014057:Tomography, X-Ray Computed
D001466:Barium Sulfate