Pelvic actinomycosis

Pelvic actinomycosis is a rare disease that may complicate longstanding intrauterine device (IUD) use. Its timely recognition is crucial to minimize morbidity and avoid the erroneous diagnosis of malignancy with subsequent, unnecessary surgery. We describe a case of pelvic actinomycosis. The role of magnetic resonance imaging (MRI) in recognizing this infectious disease process is stressed.

DISCUSSION
Actinomyces israelii is a gram-positive, anaerobic, non-acid-fast, filamentous opportunistic bacterium of the order Actinomycetales. It is normallypresent in the oropharynx and gastrointestinal tract but not in the vagina.4 Pelvic actinomycosis caused by A. israelii usually occurs in the presence of damaged tissue (e.g., with prolonged IUD use). Actinomycosis is a chronic, suppurative and granulomatous disease that grows irrespective of anatomic barriers because of the proteolytic enzymes released by the organism.It is characterized by extensive fibrosis, with multiple abscesses and sinus tract formation. This disease typically affects women of reproductive age who have had an IUD in place for more than 3 years. The clinical presentation of pelvic actinomycosis is nonspecific. Therefore, the correct diagnosis is rarely considered preoperatively, with many patients undergoing total abdominal hysterectomy and bilateral salpingooophorectomy for a presumed ovarian cancer. Definitive diagnosis is generally based on histopathologic identification of the actinomycotic granules or culture of the Actinomyces sp. or both.2 Long-term high-dose penicillin with IUD removal is an effective treatment. Although imaging signs of pelvic actinomycosis are nonspecific, certain findings on cross-sectional imaging, especially on MRI, are suggestive. The transvesical sonographic signs of pelvic actinomycosis previously reported in the literature include IUD in situ, uterine enlargement and an ill-defined solid or cystic adnexal mass. Involvement of the urinary bladder, ureters or sigmoid colon has also been reported,4 reflecting the invasiveness of this disease. In our patient, the EVS findings of symmetric sigmoid wall thickening with inflamed pelvic fat favoured an inflammatory over a malignant process. However, the appearance of enlarged heterogeneous ovaries was nonspecific. CT of the pelvis is ideally suited for depicting diffuse bowel wall thickening, enhancement of the pelvic fat, obliteration of tissue planes and intensely enhancing pseudotumoral phlegmonous foci with or without abscess formation. However, CT is poor at characterizing adnexal enlargement and often results in nonspecific findings. Ascites and lymphadenopathy are not typical features of this disease. Among the reported cases in the literature, very few patients demonstrated minimal ascites and reactive lymphadenopathy. MRI with its multiplanar capability exquisitely illustrates the infiltrative behaviour of this disease. When cross-sectional imaging in a long-term IUD user shows pelvic disease that has no regard for tissue planes, and thus results in multiorgan involvement, with inflamed pelvic fat and intra- or extra-ovarian abscesses, which can be well assessed on pelvic MRI, pelvic actinomycosis should be considered. This diagnosis is substantiated by the presence of fever, leukocytosis and no serum markers that are characteristic of ovarian cancer. If doubt persists, EVS or CT-guided biopsy or aspiration can be helpful in establishing the diagnosis. Imaging is also critical in assessing the response to conservative management.