Perianal abscess caused by Actinomyces: report of a case.

Most anal abscesses are caused by anal fistula and invasion of the surrounding tissues by a mixed colonic flora. The treatment comprises excision of the abscess and. if appropriate, fistulectomy. Primary anorectal actinomycosis and perianal actinomycosis are very rare and are caused by Actinomyces, which is a ubiquitous microaerophilic bacterium. Here we report a case of perianal actinomycosis. The patient had a short history of painless perineal induration without fever or leucocytosis with normal routine blood tests. After excision sulphur granules drained from the cavity and the pathological investigations were indicative of perianal actinomycosis. Appropriate surgery and antibiotic treatment healed the perianal infection. After elimination of other diagnoses, e.g. Crohn's disease, tuberculosis and malignant growths, this rare case of perianal actinomycosis should be kept in mind in the differential diagnosis of a painless perianal mass.