Myung-Min Choi, et al. nosed preoperatively.16 In our series, only one patient (4.5%) was diagnosed before surgery. Intrabdominal actinomycosis can appear as an abdo- minal mass of ambiguous benignity and can mimic a malignant tumor. For example, actinomycosis of the colon or the greater omentum is a rare differential diagnosis of colonic carcinoma or peritoneal tumor.17-19 The pathogenesis of abdominal actinomycosis is not yet well understood. There are two possibilities suggested that can affect intrabdominal organs: through blood-borne infection or by swallowing.20 Actinomyces can normally inhabit colon, predominating in areas of stagnation i.e. the cecum and appendix. Actinomyces requires injury to the normal mucosa to penetrate and cause disease. Predisposing factors may include appendicitis and diverticulitis, gast- rointestinal perforations, previous surgery, foreign bodies, or neoplasia.21 Thus, intrabdominal actinomycosis should be included in differential along with other inflammatory diseases such as ulcerative colitis, Crohn’s disease, tuber- culosis, diverticulitis and pelvic inflammatory disease. Pelvic actinomycosis has recently become more preva- lent and is associated almost exclusively with women who use IUDs.16 Orogentital tract is thought to be an important mode of acquiring this type of infection in lower genital tract.22 In the uterine cavity, the microorganisms are appa- rently confined to the superficial layers of the mucosa, a fact perhaps related to its cyclic shedding. The most likely route of spread with subsequent development of pelvic abscess appears to be through patent fallopian tubes. The use of IUD may increase the risk of infection through injury to the normal uterine mucosa.13,23 Pelvic actinomy- cosis associated with the use of IUDs can mimick pelvic malignancy.24 For such reason, it is often surgically excised. However, if a diagnosis can properly be made preopera- tively, antibiotic treatment and removal of IUD may lead to complete remission, avoiding unnecessary surgery. In our series, none of the patients with IUDs was diagnosed of actinomycosis preoperatively. Fiorino25 reported 92 patients with actinomycotic abscess in 63 case reports. In this study, the average duration of IUD implantation was 8 years, and only 16% had been using an IUD for less than 3 years. Likewise, the average duration of IUD was 7 years and only 15% of those patients had IUD for less than 3 years in our study. Although IUD is strongly correlated with intrabdominal actinomycosis, a definite duration of IUD implantation and the risk of developing actinomy- cosis infection has not yet been established. The modern principle of therapy for actinomycosis began with Peabody and Seabury in 1960,26 who recom- mended abscess drainage in combination with high dose antibiotics. Smith et al.27 reported that ciprofloxacin and tetracyclines showed poor performance in antimicrobial susceptibility testing of actinomyces species. Actinomyces species appear to be susceptible to a wide range of beta- lactam agents and, when combined with beta-lactamase inhibitors, they should be regarded as agents of first choice.27 Uncomplicated actinomycosis can be medically treated by antibiotics, although there are differing opinions in the literature about dosage and duration of antibiotic treat- ment.28,29 A prolonged treatment course is required because of the poor penetration of antibiotics into the fibrotic tissues. Thus, when there are more avascular spaces present due to severe tissue reactions, medical therapy may be less effec- tive, resulting in longer duration of antibiotic treatment, regardless of the site of actinomycosis. Interestingly, two patients in our series (9.0%) who were treated with iv anti- biotics less than 4 weeks did not recur during the last 34 months of follow-up. Hence, the clinical impact of surgical resection followed by short-term antibiotics merits for further study. Even though intrabdominal actinomycosis is very rare in its frequency, it should be included in a list of differential diagnosis, especially in any women with a history of IUD use who presents with abdominal pain or a pelvic mass. If actinomycosis is suspected preoperatively, appropriate handling of cultures will increase the diagnostic yield which may spare the patient from an extensive surgery. REFERENCES 1. Koren R, Dekel Y, Ramadan E, Veltman V, Dreznik Z. Periappendiceal actinomycosis mimicking malignancy report of a case. Pathol Res Pract 2002;198:441-3. 2. Uchiyama N, Ishikawa T, Miyakawa K, Iinuma G, Nakajima H, Ushio K, et al. Abdominal actinomycosis: barium enema and computed tomography findings. J Gastroenterol 1997;32:89-94. 3. Milach J, Ziól kowski P, Orzel W. [A case of actinomycosis of the sigmoid in a 41-year-old woman with a clinical appearance of cancer.] Wiad Lek 1989;42:895-8. 4. Belmont MJ, Behar PM, Wax MK. Atypical presentations of actinomycosis. Head Neck 1999;21:264-8. 5. Berchtenbreiter C, Brüning R, Auernhammer A, Reiser M. Misleading diagnosis of retroperitoneal actinomycosis. Eur Radiol 1999;9:1869-72. 6. Ferrari TC, Couto CA, Murta-Oliveira C, Conceiçäo SA, Silva RG. Actinomycosis of the colon: a rare form of presentation. Scand J Gastroenterol 2000;35:108-9. 7. Anteby E, Milvidsky A, Goshen R, Ben-Chetrit A, Ron M. [IUD- associated abdominopelvic actinomycosis.] Harefuah 1991;121: 150-3. 8. Atad J, Hallak M, Sharon A, Kitzes R, Kelner Y, Abramovici H. Pelvic actinomycosis. Is long-term antibiotic therapy necessary? J Reprod Med 1999;44:939-44. 9. Hinnie J, Jaques BC, Bell E, Hansell DT, Milroy R. Actinomy- cosis presenting as carcinoma. Postgrad Med J 1995;71:749-50. 558 Yonsei Med J http://www.eymj.org Volume 50 Number 4 August 2009