Differences in clinical manifestations and CT features between pulmonary actinomycosis and aspergillus nodules, as revealed by a solitary pulmonary nodule or mass

Abstract

Background: Pulmonary actinomycosis is a rare bacterial disorder often misdiagnosed as other pulmonary diseases because of a lack of specific characteristics and radiographic findings. Aspergillus nodules, a common fungal infection and form of chronic pulmonary aspergillosis, have imaging findings that overlap with those of pulmonary actinomycosis. This study reviews patients’ clinical and imaging data, to differentiate pulmonary actinomycosis from Aspergillus nodules. Methods: This retrospective study included 17 patients with pulmonary actinomycosis and 25 patients with Aspergillus nodules diagnosed histopathologically in a tertiary Chinese hospital between June 2014 and January 2022. Data on age, sex, lesion types/locations, and CT findings were analyzed. Results: No significant differences were found in age (mean age 58.2 ± 7.7 vs. 57.2 ± 11.9; p = 0.76), but statistically significant differences were found in sex (men 13 vs. women 10; p = 0.02), between groups. Common symptoms between groups included cough, hemoptysis, sputum production, fever, and chest pain, which showed no significant between-group differences (p = 0.09, p = 0.28, p = 0.10, p = 1, p = 0.41, respectively). Visual evaluation revealed that pulmonary actinomycosis lesions were more likely than pulmonary aspergillosis to appear mass-like (p < 0.001), with bulky volume (p = 0.002), ill-defined margins (p = 0.045), and interlobular septal thickening (p = 0.008). Pleural changes and mediastinal or hilar lymphadenopathy were more common in pulmonary actinomycosis than in Aspergillus nodules (p = 0.037, p = 0.010, respectively), whereas cavitation, an air-crescent sign, and bronchiectasis were more common in pulmonary aspergillosis (p = 0.027, p < 0.001, p = 0.016, respectively). Conclusion: Distinguishing between pulmonary actinomycosis and Aspergillus nodules on the basis of clinical manifestations alone is difficult, although distinctive CT findings may differentiate the two diseases.