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Abdominal actinomycosis

Louis-Michel Wong Kee Song, MD, FRCP(C)
Norman E Marcon, MD, FRCP(C)
Section Editor
Stephen B Calderwood, MD
Deputy Editor
Anna R Thorner, MD


A number of disorders are associated with lesions in the ileocecal region. Examples frequently encountered in developed countries include colon cancer, Crohn's disease, and, less commonly, infection due to Yersinia enterocolitica and Y. pseudotuberculosis (see related topic reviews). Many other infectious, neoplastic, and drug-related causes of ileocecal lesions have been described.

This topic review will provide an overview of abdominal actinomycosis, which is one of the causes of ileocecal lesions that are frequently considered in specific clinical settings or when more frequent causes have been excluded or are unlikely. The others (including mucoceles, tuberculosis, typhlitis, carcinoid, and lesions due to nonsteroidal anti-inflammatory drugs) are discussed separately. (See appropriate topic reviews.)


Actinomycosis is an uncommon, chronic granulomatous disease caused by filamentous, gram-positive, anaerobic bacteria [1]. Actinomyces israelii is the major human pathogen [1,2]. Actinomycosis has a worldwide distribution, affects mostly middle-aged individuals, and is two to four times more common in men [2-4].


Actinomycetes are commensal inhabitants of the oral cavity and intestinal tract [5] but acquire pathogenicity through invasion of breached or necrotic tissue. As the infection progresses, granulomatous tissue, extensive reactive fibrosis and necrosis, abscesses, draining sinuses, and fistulas are formed [2].

Infection involving the cervicofacial area is most common (50 percent), followed by abdominal involvement (20 percent) and thoracic involvement (15 to 20 percent) [1]. In abdominal actinomycosis, the appendix and ileocecal region are usually involved [1,6]. The disease tends to remain localized as the infection spreads contiguously, disregarding tissue planes. Lymphadenopathy is not a clinical feature. Hematogenous dissemination is also rare [1,2]. (See "Cervicofacial actinomycosis".)

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Literature review current through: Nov 2017. | This topic last updated: Aug 04, 2017.
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