Imaging of Actinomycosis in Various Organs: A Comprehensive Review

Abstract

Actinomycosis is a chronic suppurative bacterial infection caused by Actinomyces species. Actinomyces israelii is the organism most commonly found in human disease. Actinomycosis usually manifests with abscess formation, dense fibrosis, and draining sinuses. The disease is further characterized by the tendency to extensively spread beyond normal fascial and connective tissue planes. Actinomycosis occurs most commonly in the cervicofacial region (50%-65%), followed by the thoracic (15%-30%) and abdominopelvic (20%) regions, but rarely involves the central nervous system. Most cases of cervicofacial actinomycosis are odontogenic in origin. In the acute form, cervicofacial disease can manifest with soft-tissue swelling, a painful pyogenic abscess, or a mass lesion. In the subacute to chronic form, a painless indurated mass can spread to the skin, leading to draining sinus tracts. Thoracic manifestations include parenchymal, bronchiectatic, and endobronchial actinomycosis. At computed tomography, pulmonary actinomycosis usually appears as chronic segmental airspace consolidation containing necrotic low-attenuation areas with peripheral enhancement. Abdominopelvic actinomycosis preferentially involves the ileocecal region, ovary, and fallopian tube. The imaging findings favoring abdominopelvic actinomycosis include strong enhancement in the solid portion of the mass after contrast material administration, small rim-enhancing abscesses within the mass, and extensive inflammatory extensions. Actinomycosis in the central nervous system may produce brain abscess, meningitis, subdural empyema, actinomycetoma, and spinal and cranial epidural abscess. In general, actinomycosis responds well to antibiotic therapy, but long-term follow-up after treatment is needed because of frequent relapses.

Actinomyces and Related Organisms in Human Infections

“…For example, in a recent case series of 94 thoracic actinomycosis cases (60), one-third of the cases were initially diagnosed as lung cancer, and only 6% were diagnosed as actinomycosis. Radiographic imaging techniques, such as computed tomography, and magnetic resonance imaging are valuable diagnostic tools for recognizing the location and size of the lesion(s) (61)(62)(63). Characteristic features of actinomycosis include chronic manifestations, abscess formation with sinus tracts, and purulent discharge (9).…”

CT findings in acute peritonitis: a pattern-based approach

“…Actinomycosis is a rare infection which manifests with abscess formation and dense fibrosis and involves the ileocecal region, ovary, and fallopian tube (22). Pelvic actinomycosis is usually associated with a history of long-term intrauterine contraceptive device use.…”

“…The strong contrast enhancement is due to the presence of granulation tissue. Ascites is usually minimal or absent (22). These features may raise concern for neoplastic disease which has to be considered in the differential diagnosis.…”

“…These features may raise concern for neoplastic disease which has to be considered in the differential diagnosis. Combining clinical history (pain, leukocytosis, long-term history of intrauterine device) with CT findings of an infiltrative mass showing dense contrast enhancement without significant ascites, pelvic actinomycosis should be considered before planning surgery (22) (Fig. 11).…”

Actinomicosis torácica: presentación de un caso

“…2 En la tomografía de tórax, se observa consolidación en parches, derrame pleural, linfadenopatías regionales y erosión ósea. 3,9 La consolidación pulmonar con compromiso pleural y de la pared torácica es una tríada característica de actinomicosis torácica. 9 El tratamiento médico es antibioticoterapia prolongada.…”