Actinomycosis of the distal colon and rectum.

Actinomycosis of the colon has rarely been reported; two such cases are presented. A predisposing factor appears to be the presence of a pre-existing intrauterine device (IUD). This history was present in one case in which there was perisigmoid abscess, local extension, and fistulous tract or the anterior abdominal wall. A second patient had anorectal involvement which resembled Crohn's disease, and was found to be HIV positive. There was mucosal irregularity, wall thickening, reactive adenopathy, perirectal fascial thickening, and a sinus tract, which responded well to penicillin. It is unclear if there is an increased incidence of clinical actinomycosis in the HIV positive population, as it has not to our knowledge been previously reported.