| Chest radiograph or CT abnormality | Etiology by rate of disease progression | Etiology by rate of disease progression |
| Acute <24 hours* | Chronic | |
| Consolidation | Any organism (especially bacteria) | Fungi Nocardia spp, Actinomyces spp Mycobacteria Bronchoalveolar cancer Bronchiolitis obliterans organizing pneumonia |
| Diffuse interstitial infiltrate | Pneumocystis jirovecii Bacteria (especially Haemophilus influenzae) Virus (Influenza, CMV) Pulmonary edema Acute respiratory distress syndrome | Mycobacteria Drug toxicity Lymphocytic interstitial pneumonia Metastatic disease Pulmonary alveolar proteinosis |
| Nodular infiltrate | Bacteria
| Nocardia spp, Actinomyces spp Fungi Kaposi's sarcoma Other tumors (especially lung cancer) Castleman's Disease |
| Adenopathy | Lymphoma Kaposi's sarcoma Castleman's Disease Lung cancer Tuberculosis | |
| Pleural effusion | Bacteria (parapneumonic) Tuberculosis Empyema | Lymphoma (especially non-Hodgkin's lymphoma and primary effusion lymphoma) Kaposi's sarcoma |
| Pneumothorax | P. jirovecii |
