Fact-sheet: Actinomycosis
Updated on 08/17/2020 at 3:32 PM
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Definition
Infection due to a Gram-positive anaerobic bacterium: actinomyces, a saprophyte of the oral and intestinal flora.
This bacterium has a proteolytic enzyme, resulting in pseudotumoral infiltration.
This infection is more common in women, chronic, with a preferential pelvic location in patients with intrauterine devices (IUDs) left in place beyond the recommended duration.
Infection via digestive tract breach after surgery is also possible.
ENT and pulmonary locations exist.
Presacral location is common.
Clinical features
Triad:
- Pelvic and abdominal pain
- Impaired general condition
- Infectious syndrome.
Ultrasound
Nonspecific: endometritis, hydrosalpinx, tubo-ovarian abscess.
Hydronephrosis is frequent.
CT
The distinctive feature of actinomycotic infection is its disregard for anatomical boundaries and an almost tumor-like extension.
- Nonspecific appearance of gynecologic infection, such as endometritis, unilateral or bilateral suppurative salpingo-oophoritis, or tubo-ovarian abscess
- Presence of dense fibrosis.
- Infiltration of the greater omentum
- Retractile appearance with attraction of neighboring organs.
- Extrinsic peritoneal masses infiltrating and fistulizing into digestive structures
- Ureterohydronephrosis
- A necrotic center is common.
- Cutaneous fistulization
MRI
Useful for differential diagnosis, given the inflammatory, pseudotumoral, and infiltrative appearance.
Infiltrating mass with intermediate, heterogeneous T2 signal.
Microabscesses within the mass with T2 hyperintensity and peripheral enhancement after gadolinium injection.
Presacral location ++.
Retractile effect on neighboring structures.
Management
- Biopsy or gynecologic sampling.
- Management with antibiotic therapy (penicillin)
- Highly mutilating surgery, to be avoided.
Differential diagnosis
- Peritoneal carcinomatosis
- Peritoneal pseudomyxoma