Bronchiolitis differential diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Ahmed Elsaiey, MBBCH [2]

Overview

Bronchiolitis must be differentiated from other respiratory and cardiac diseases that present with similar clinical manifestations of cough and dyspnea. Bronchiolitis should be differentiated from asthma, COPD, pneumonia, congestive heart failure, diffuse idiopathic neuroendocrine cell hyperplasia, tuberculosis, pertussis, foreign body aspiration, pulmonary embolism, and Harman-Rich syndrome.

Differentiating bronchiolitis from other diseases

Bronchiolitis must be differentiated from other respiratory and cardiac diseases that can cause the similar clinical manifestations like cough and dyspnea. The differentials include the follwoing:

Diseases	Symptoms			Signs			Diagosis
	Fever	Chest pain	Cough	Wheeze	Crackles	Tachycardia	Lab tests	Imaging
Bronchiolitis	+/-	-	Dry	+	+	+/-	ELISA and immunoassays may be done in case of RSV infection Pulmonary function test to exclude other lung diseases	CT scan shows: Intense bronchiolar mural inflammation Bronchial wall thickening Centrilobular nodules with tree-in-bud pattern
Asthma	-	-	Dry/Productive	+	-	-	Pulmonary function tests (PFT) to exclude other diseases Serum examination shows elevated level of eosinophils due to allergy	CT scan shows: Dilated bronchi Bronchial wall thickening Air trapping
Chronic obstructive pulmonary disease (COPD)	+	-	Productive	+	+	+	Spirometry: FEV1/FVC < 70% Arterial blood gases: Hypoxemia Hypercapnia Sputum culture	EKG may show: P pulmonale Right ventricular hypertrophy Narrow QRS CT scan is more sensitive in diagnosing COPD than X-ray
Bacterial pneumonia	+	+	Productive	+	+	+/-	Diagnosis depends on presentation and physical examination Laboratory tests Arterial blood gases may show hypoxia and acidosis Sputum culture	Chest X-ray may show: Pleural effusion Inflitrates within the lungs CT scan may show: Consolidation Ground glass appearance
Pulmonary embolism (PE)	+/-	+	Bloody	+	+	+	Arterial blood gases may show: Hypoxemia Hypocapnia Respiratory alkalosis Increased alveolar-arterial gradient D-dimer assay may show elevated levels of D-dimers Hypercoagulability tests for patients with: Unprovoked venous thrombosis at an early age (< 40 years) Family history of VTE syndromes Routine blood tests are non specific	CT pulmonary angiography is the gold standard imaging to diagnose pulmonary embolism. CT may show: Acute: Centrally located thrombus occluding the vessel Chronic: Eccentric changes in the vessel wall, recanalization in the thrombous and arterial web EKG is neither specific nor sensitive in diagnosing PE but it may show: T wave inversion P pulmonale Sinus tachycardia Chest X-ray to exclude other differentials
Diffuse idiopathic neuroendocrine cell hyperplasia	-	-	Dry	+	-	-	Pulmonary function test shows obstructive lung disease (FEV1/FVC less than 0.7)	CT scan may show: Multiple nodules Ground glass appearance Bronchiectasis
Tuberculosis	+	+	Bloody	-	-	-	Sputum culture: Three successive positive cultures for M. tuberculosis confirm the diagnosis Presence of acid fast bacilli in sputum smear indicates tuberculosis	Chest X-ray is an important diagnostic imaging procedure in TB diagnosis. X-ray may show: Parenchymal infilration Hilar adenopathy Nodules Pleural effusion CT scan may show: Micronodules Cavitation Consolidation Interlobular septal thickening EKG may show abnormalities in the case of pleural effusion associated with TB. These abnormalities include: Low QRS voltage  Electrical alternans
Interstitial pneumonitis (Hamman - Rich syndrome)	+	-	Productive	-	+	-	Arterial blood gases may show: Hypoxemia PaO2/FiO2 less than 200 mmHg indicating acute respiratory distress syndrome Other lab tests are done to exclude other diseases	Chest X-ray may show: Bilateral opacification CT scan may show Ground glass appearance Bronchoscopy to exclude other causes such as: Alveolar hemorrhage Lymphoma Lung biopsy is done: In unclear cases; to confirm acute interstitial pneumonitis Exclude other causes of ARDS
Foreign body aspiration	+	+	Bloody	+	-	-	Lab tests to evaluate the ventilation function	Chest X-ray shows: Hyperinflation Mediastinal shift Atelectasis
Pertussis	+		Dry	-	-	-	Nasopharyngeal swab for PCR testing Sputum culture Serology to detect pertussis toxin	No remarkable imaging findings
Congestive heart failure	-	+ while walking	Dry/Productive	-	-	+	Routine lab tests to identify the cause of the heart failure: Renal function tests including urinalysis and electrolytes Complete blood count Thyroid studies in patients being treated with concomitant therapy such as amiodarone Biomarkers: BNP or NT-proBNP Cardiac troponin T or I Carbohydrate Antigen 125	EKG to detect underlying cause Chest X-ray shows cardiomegaly Echocardiography is done: To determine stroke volume To assess type of heart failure