History
A detailed clinical history is critical as in any other pathologic entity. Diagnostic consideration of actinomycosis is reasonable under the following circumstances [6] :
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The timeline of the clinical manifestations demonstrate chronicity of the event, in association with a firm masslike lesion with extensive compromise of tissue planes.
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Drainage of an abscess by a sinus tract.
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Temporary improvement after a course of antibiotic therapy, followed by relapsed disease, and recurrences
Physical Examination
Presentations
Most cases of actinomycosis present in the orocervicofacial region (50-65%); the majority of them are of odontogenic origin. Invasive dental procedures and tooth extractions facilitate the access of Actinomyces to deeper tissues. Early diagnosis of infection is challenging owing to the nonspecific and inconsistent signs and symptoms at this stage, such as edema, cough, occasional pain, and low-grade fever. Less frequently, a soft-tissue mass or abscess is present in the acute to subacute phases. [6, 19] As the infection evolves, the lesion extends within the soft tissues, growing as a fibrotic mass, spreading and dissecting through tissue planes, and forming sinus tracts, which may drain to the skin's surface. [6] Skin discoloration may be seen in the acute phase. [3] Cutaneous inflammatory changes in association with the draining sites are common. Up to 75% of cases drain yellow, purulent material from these sites, known as sulfur granules, which are strongly suggestive of, but nonspecific for, actinomycosis. Other entities such as nocardiosis and various fungal infections may manifest with the production of identical material. [3, 28]
Actinomycosis of the thoracic region (10-30%) may be secondary to the extension of local infections or hematogenous spread, or due to aspiration of oropharyngeal secretions. [8] It may manifest as an endobronchial infection, nodule/mass, pneumonia, pleural effusion, or, less commonly, with mediastinitis. [19] As mentioned, the infectious process by Actinomyces characteristically extends throughout different tissue planes despite anatomic barriers. Cases of thoracic actinomycosis presenting as empyema necessitans have been described. [29, 30]
Abdominopelvic actinomycosis (20%) is usually the result of gastrointestinal tract mucosal disruption by perforation, trauma, or surgical intervention. [5, 8, 19] Pelvic disease has been associated with the use of intrauterine contraceptive devices, although most women, despite the presence of Actinomyces infection, are asymptomatic. [31, 32] Abdominopelvic disease may start as an abdominal focus extending to the pelvic region, or vice versa. [10]
Other possible but uncommon sites of infection by Actinomyces include the central nervous and musculoskeletal systems, and its disseminated form. [5, 8, 33]
Findings
Actinomycosis may present as a phlegmon, abscess, firm mass, or a draining sinus in any of the regions of presentation. The clinical findings are variable and may resemble other inflammatory, infectious, and/or neoplastic lesions. Imaging, tissue sampling, and microbiologic correlation are advised to prompt early, accurate diagnosis and treatment. [6]
Complications
Actinomycosis can result in extensive regional tissue invasion and markedly morbid functional and structural compromise of organs and systems. Skin defects and scarred tissue may require resective and reconstructive surgical interventions.
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Photomicrograph of gram-positive organisms in actinomycosis, which may be confused with those causing a mycotic infection (hematoxylin and eosin, original magnification X40).
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Photomicrograph of a characteristic sulfur granule of actinomycosis (hematoxylin and eosin, original magnification X10).
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Oral fistula due to actinomycosis.
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Periapical radiograph shows infection in the premolar tooth.
