Differentials
Nodular sarcoidosis
SIGNS / SYMPTOMS
No particular differentiating signs and symptoms.
INVESTIGATIONS
CXR may show enlarged hilar lymph nodes.
Chronic eosinophilic pneumonia (CEP)
SIGNS / SYMPTOMS
No particular differentiating signs and symptoms.
INVESTIGATIONS
High-resolution chest CT scan (HRCT) in CEP shows peripheral ground-glass opacities with sparing of the central portions of the lungs.
CBC with differential may show increased blood eosinophils.
Bronchoalveolar lavage with eosinophil count in excess of 30%.
Nonspecific interstitial pneumonia (NSIP)
SIGNS / SYMPTOMS
Shortness of breath will be progressive and crackles will persist while the patient is receiving corticosteroid therapy.
INVESTIGATIONS
HRCT in NSIP shows ground glass opacities +/- traction bronchiectasis and honeycombing with subpleural sparing.[55]
Idiopathic pulmonary fibrosis with a usual interstitial pneumonia (UIP) pattern
SIGNS / SYMPTOMS
Patients with UIP will have progressive shortness of breath and increasing degree of bilateral crackles.
INVESTIGATIONS
HRCT shows linear opacities at the lung bases, traction bronchiectasis, and subpleural honeycombing.
Granulomatosis with polyangiitis (formerly known as Wegener granulomatosis)
SIGNS / SYMPTOMS
Patients with granulomatosis with polyangiitis (formerly known as Wegener granulomatosis) may have nasal-sinus and renal symptoms.
INVESTIGATIONS
HRCT shows bilateral multiple cavitary lesions.
A positive ANCA is typically present.
Acute interstitial pneumonia
SIGNS / SYMPTOMS
Symptoms and findings same as for rapidly progressive OP.
INVESTIGATIONS
HRCT may show disrupted lung architecture with traction bronchiectasis and early honeycombing.
Pulmonary metastasis and primary adenocarcinoma
SIGNS / SYMPTOMS
Symptoms of cough and shortness of breath progress when the patient is treated with corticosteroids.
INVESTIGATIONS
Kerley B lines occur in carcinomatosis.
Chest x-ray may detect a solitary pulmonary nodule, mass, pleural effusion, lung collapse, or mediastinal or hilar fullness.
Chest CT scan shows size, location, and extent of primary tumor; evaluates for hilar and/or mediastinal lymphadenopathy and for distant metastases.
Sputum cytology shows malignant cells in sputum.
Bronchoscopy shows endobronchial lesions.
Biopsy shows confirmation of malignancy.
Pulmonary tuberculosis
SIGNS / SYMPTOMS
Symptoms of cough, hemopytsis, and shortness of breath become progressive with corticosteroid treatment.
INVESTIGATIONS
HRCT shows upper lung nonlayering cavitary lesions.
Sputum culture with positive AFB organisms.
Community-acquired pneumonia
SIGNS / SYMPTOMS
Symptoms of cough, sputum production, and fever subside with antibiotic therapy.
INVESTIGATIONS
Chest x-ray shows patchy infiltrates beginning to resolve with antibiotic therapy.
Bronchioloalveolar cell carcinoma
SIGNS / SYMPTOMS
Symptoms will be similar for bronchioloalveolar cell carcinoma and OP.
INVESTIGATIONS
There may be a pleural tag and the process bending or crossing the fissures on HRCT.
Coronavirus disease 2019 (COVID-19)
SIGNS / SYMPTOMS
Residence in/travel to a country/area or territory with local transmission, or close contact with a confirmed or probable case of COVID-19, in the 14 days prior to symptom onset.
Signs and symptoms are similar so it may be difficult to differentiate between the conditions clinically.
INVESTIGATIONS
Real-time reverse transcription polymerase chain reaction (RT-PCR): positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA.
It is not possible to differentiate COVID-19 from other causes of pneumonia on chest imaging.
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