Perianal actinomycosis--a complication of a fistula-in-ano. Report of a case.

Perianal actinomycosis is a rare complication of fistula-in-ano. We report a case of an 82-year-old male with an atypical fistula that had an internal opening at a posterior crypt and, over an extense perianal and gluteal area, induration with multiple suppurative draining sinus tracts. He underwent fistulotomy and an ample excision of the diseased areas. The pathology report was actinomycosis. Further treatment with antibiotics was continued until the patient was clinically cured. The diagnosis of perianal actinomycosis requires a high degree of suspicion, and should be kept in mind when a fistula presents the aforementioned characteristics or in case of a recurrence after adequate surgical therapy.