PMC9626365_01
A 67-year-old man with a pulmonary arterial pseudoaneurysm (PAP) due to pulmonary actinomycosis. (A,B) Contrast-enhanced CT images obtained with lung and mediastinal window settings show a fluid collection in the lingular segment of the left lung, suggesting a lung abscess. (C) Contrast-enhanced CT image obtained with mediastinal window settings almost at the same level as A and B shows a 15-mm hyperenhancing nodule with the same attenuation as the aorta within a segmental consolidation with an internal low-density area in the left lingular segment. (D) Maximum intensity projection (MIP) image of c demonstrates the PAP (arrow). (E) Selective angiogram of the left pulmonary artery after embolization of the left bronchial artery and the seventh to ninth intercostal arteries shows a faint bronchial artery-pulmonary artery fistula with a saccular dilatation (arrow). (F) A Gram stain of the specimen shows numerous Gram-positive filamentous branching bacteria in the bronchial lumen.
gr1.jpg
PMC9626365_01_gr1.jpg
fig0001
Contrast-enhanced CT demonstrated a 15-mm hyperenhancing nodule with the same attenuation as the aorta within a segmental consolidation with an internal low-density area in the left lingular segment (Fig. 1C and D). Although the left pulmonary and bronchial angiograms were performed, no pseudoaneurysm was observed. A selective angiogram of the left pulmonary artery after embolization of the left bronchial artery and the seventh to ninth intercostal arteries with a gelatin sponge showed a faint saccular dilatation of the left pulmonary artery (Fig. 1E). Actinomyces colonies in the bronchial lumen (Fig. 1F). A CT scan obtained 7 days after the surgery showed residual pleural effusion between the left upper and lower lobes.
PMC9626365_02
A 51-year-old man with a pulmonary arterial pseudoaneurysm (PAP) due to pulmonary actinomycosis. (A) CT image obtained with lung window settings shows consolidation in the lower lobe of the left lung, suggesting a lung abscess. (B,C) Contrast-enhanced CT images obtained with lung and mediastinal window settings show consolidation with a cavity in the left lower lobe of the lung suggestive of an abscess. (D,E) Selective angiogram and CT angiogram of the left bronchial artery revealed a 7 mm pseudoaneurysm at the peripheral part of the bronchial artery in the left lower lobe of the lung (arrow). (F) Photomicrograph of the histopathologic specimen shows filamentous structures that are positive for Grocott-Gomori methenamine-silver staining.
gr2.jpg
PMC9626365_02_gr2.jpg
fig0002
A chest CT scan revealed consolidation in the lower lobe of the left lung, suggesting a lung abscess (Fig. 2a). Contrast-enhanced CT demonstrated consolidation with a cavity in the left lower lobe of the lung, suggestive of an abscess (Fig. 2B and C), and antibiotic treatment with garenoxacin was administered. Four days later, a left lower lobectomy was performed, and a histological diagnosis of pulmonary actinomycosis was made (Fig. 2F).