Actinomycosis of the ano-rectum: a rare infectious disease mimicking carcinomatosis.

Abdominal actinomycosis is an infectious disease caused by Actinomyces israeli, a usual germ of the gastro intestinal tract. It gives unusual tumoral lesions with abcesses and fistulas. More rarely is abdominal actinomycosis at the end of the abdominal tube. Cope in 1949 said: "Actinomycosis occurs so seldom in the colon and the rectum that no surgeon, even if he be a proctologist is likely in a life time to see more than a few cases" (4). An anorectal actinomycosis case that looked like rectal cancer is reported. It was treated successfully by surgery and antibiotherapy. Some anatomopathologic and mainly histologic characteristics lead to the diagnosis. General and pathological aspects, symptoms, diagnosis, differential diagnosis and therapy of anorectal actinomycosis are discussed.