Chronic airspace disease: Review of the causes and key computed tomography findings

Table 2 Clinical, laboratory and imaging findings, and prognosis/treatment of infectious causes of chronic airspace disease

Causes of chronic airspace disease/ General category	Clinical information	Laboratory findings	Imaging findings	Prognosis and treatment
Fungal infection, including angio-invasive aspergillosis/ Infectious	History of immunosuppression including: Neutropenia; High-dose steroid treatment; Bone marrow transplant; End-stage AIDS; Symptoms are nonspecific (fever, cough, pleuritic chest pain, hemoptysis)	Neutropenia, especially severe (absolute neutrophil count < 500 cells/µL)	Parenchymal nodules or consolidation with a surrounding area of ground glass opacity (halo sign); Reverse halo sign; Peripheral wedge-like areas of consolidation representing hemorrhagic pulmonary infarct; Pleural effusion and lymphadenopathies are rare	Intravenous amphotericin B; Poor prognosis; Early diagnosis improves survival
Pulmonary tuberculosis/ Infectious	Immunosuppression such as AIDS; Recent travel to endemic countries	Low CD4 count in AIDS patients (< 350 cells/mm3)	Primary tuberculosis: Not detectable; Patchy or even lobar consolidation; Cavitation is rare; Military (numerous tiny nodules) tuberculosis can be seen Post-primary tuberculosis: Mostly involve the posterior segments of the upper lobes or superior segments of the lower lobes; Patchy consolidation with or without ground-glass opacity; Cavitation is more common; Military (numerous tiny nodules) tuberculosis can be seen	Appropriate antibiotics based on sensitivity; Respiratory isolation if needed
Non-tuberculosis MAC infection/ Infectious	May have pre-existing pulmonary disease or depressed immunity; Can also happen in otherwise normal people; Predilection for older women who voluntary suppress cough (Lady Windermere syndrome)		Most common: Bronchiectasis and bronchial wall thickening with small centrilobular nodules and tree-in-bud appearance; Persistent consolidation and ground-glass patchy opacities; Upper lung cavitary lesions	No clear gold-standard for treatment; Usually need multiple antibiotics; May be candidate for resection of the involved lung if the disease is localized; More aggressive course in upper lung cavitary form More indolent course in nodular bronchiectatic form
Incompletely treated bacterial infection/ Infectious	History of recent bacterial pneumonia with incomplete treatment	Persistent leukocytosis	Persistent consolidation	Continued treatment with appropriate antibiotic
Pneumocystis jirovecii pneumonia/ Infectious	HIV (+) patients; Post-transplant patients; Patients undergoing chemotherapy or with hematologic malignancies; Patients with connective tissue disorder on corticosteroid treatment	CD4 counts < 200 cells/mm	Ground-glass opacity mainly with perihilar or mid zone distribution, most common findings; Less common/less typical findings septal thickening and crazy paving, pneumatocele; Pleural effusion and lymphadenopathy are unusual	Trimethoprim-sulfamethoxazole as treatment or for prophylaxis

AIDS: Autoimmune deficiency syndrome; HIV: Human immunodeficiency virus; MAC: Mycobacterium avium complex.