Lung Incidentaloma

During the evaluation of a 61-year-old man who had sustained mild head and upper trunk injuries in a car accident, a right lower lobe consolidation was noted on the chest radiograph. There was no evidence of rib fracture. A chest CT scan with contrast showed a hilar mass that obstructed the lateral segmental bronchi of the right lower lobe (A, arrow). Atelectasis of the posteromedial segments of the right lower lobe and ipsilateral subcarinal adenopathy were also noted (B).

The patient had a 60 pack-year smoking history. For the past 4 days, he had had flu-like symptoms but considered himself generally healthy. He took no medications. Except for decreased air entry over the right lower lung field, vital signs and physical findings were normal.

The CT findings along with the history of heavy smoking raised the suspicion of lung cancer, and bronchoscopy with multiple transbronchial biopsies was performed. Histopathological examination showed chronic submucosal inflammation and clusters of microorganisms with sulfur granules; these findings were consistent with Actinomyces infection.

A presumptive diagnosis of actinomycosis can be made by the identification of sulfur granules in the abscess or in discharged material from the sinus tract. Diagnosis of this chronic, progressive infection is established by culture in fewer than 50% of cases.¹

Cervicofacial actinomycosis is the most common clinical form of the disease. Dental extractions, carious teeth, and maxillofacial trauma are often precursors. Thoracic actinomycosis is usually caused by aspiration of infected material in the oropharynx. Normal gravitational and anatomical factors result in a predominance of lower lobe pulmonary disease. Chronic pneumonia occurs, which may be associated with pleuritis, abscess, and fibrosis. Radiographic findings include peripheral nonsegmental basilar infiltrates, masslike consolidation, cavitation, and pleural effusion or pleural thickening.²

The differential diagnosis includes other bacterial or fungal pneumonias and primary or secondary neoplasms. It is especially important to exclude the possibility of a neoplasm when the chest wall is involved.

This patient received intravenous penicillin. Recovery was uneventful.

References:

REFERENCES:

1

. Bennhoff DF. Actinomycosis: diagnostic and therapeutic considerations and a review of 32 cases.

Laryngoscope.

1984;94:1198-1217.

2

. Flynn MW, Felson B. The roentgen manifestations of thoracic actinomycosis.

Am J Roentgenol Radium Ther Nucl Med

. 1970;110:707-716.