Asthma Differential Diagnoses

Updated: Nov 19, 2017
  • Author: Michael J Morris, MD, FACP, FCCP; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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DDx

Diagnostic Considerations

Vocal cord dysfunction or inducible laryngeal obstruction (ILO)

Vocal cord dysfunction may exist alone or with asthma, it is caused by paradoxical adduction of the vocal cords during inspiration, and may disappear with panting, speech, or laughing. [45] Patients with chronic symptoms suggestive of asthma, normal spirometry, poor response to asthma medications, and frequent evaluations should be evaluated for vocal cord dysfunction. [46] Usually, the diagnosis can be made using direct laryngoscopy, but only during symptomatic periods or after exercise. The presence of flattening of the inspiratory limb of the flow-volume loop may also suggest vocal cord dysfunction, but this is only seen in 28% of patients at baseline. [47]

Tracheal and bronchial lesions

A variety of airway tumors are reported to manifest with symptoms similar to those of asthma. These tumors include endobronchial carcinoid and mucoepidermoid tumors, as shown in the images below. In one case, a 14-year-old boy with hyperlucency in the left lung was ultimately found to have a bronchial carcinoid in the left mainstem bronchus. [48]

Asthma. High-resolution CT scan of the thorax obta Asthma. High-resolution CT scan of the thorax obtained during inspiration in a patient with recurrent left lower lobe pneumonia shows a bronchial mucoepidermoid carcinoma (arrow).
Asthma. High-resolution CT scan of the thorax obta Asthma. High-resolution CT scan of the thorax obtained during expiration in a patient with recurrent left lower lobe pneumonia shows a bronchial mucoepidermoid carcinoma. Note the normal increase in right lung attenuation during expiration (right arrow). The left lung remains lucent, especially the upper lobe, secondary to bronchial obstruction with airtrapping (left upper arrow). The vasculature on the left is diminutive, secondary to reflex vasoconstriction. Left pleural thickening and abnormal linear opacities are noted in the left lower lobe; these are the result of prior episodes of postobstructive pneumonia (left lower arrow).

Other tracheal lesions can include bronchocentric granulomatosis, subglottic stenosis, subglottic web, tracheal hamartoma, bronchogenic cysts, leiomyoma, and tracheobronchopathia osteoplastica. All these types of tracheal lesions have been reported with symptoms similar to asthma.

Foreign bodies

Foreign body aspiration may cause not only localized wheezing but also generalized wheezing. Wheezing occurs in toddlers as well as in adults. As described in one patient, foreign body aspiration may necessitate bronchoscopic retrieval before the patient even recalls the inciting event, and as many as 25% of patients may never recall the event. [49] Furthermore, aspirated foreign bodies may be radiolucent and therefore not be visible on a chest radiograph.  Radiography may show unilateral hyperinflation (from air trapping), infiltrate (from occlusion of a bronchus), or may be normal.

Pulmonary migraine

Pulmonary migraine consists of combined recurrent asthma; cough with thick mucoid sputum; lower back pain radiating to the shoulder; subtotal or total atelectasis of a segment or lobe; and, occasionally, nausea with vomiting. [50] The symptoms are often accompanied closely in time by focal headache. Spastic narrowing of the bronchi is postulated—along with retained mucous secretions, smooth muscle hypertrophy, and thickened bronchial walls—to cause expiratory collapse of selected airways. Cerebral and abdominal vascular migraine episodes are believed to accompany pulmonary migraine.

Congestive heart failure

Congestive heart failure causes engorged pulmonary vessels and interstitial pulmonary edema, which reduce lung compliance and contribute to the sensation of dyspnea and wheezing. Cardiac asthma is characterized by wheezing secondary to bronchospasm in congestive heart failure, and it is related to paroxysmal nocturnal dyspnea and nocturnal coughing. [51]

Diffuse panbronchiolitis

Diffuse panbronchiolitis is prevalent in Japan and the Far East, and it may mimic bronchial asthma with wheezing, coughing, dyspnea on exertion, and sinusitis. [52] High-resolution CT (HRCT) findings include centrilobular nodules and linear markings that usually are more profuse than the multifocal bronchiolar impaction sometimes observed with asthma.

Aortic arch anomalies

Aortic arch anomalies may occur later in adulthood. In one case, the anomalies, which simulated exercise-induced asthma, were noticed first in a young woman only after a vigorous exercise program. [53] On testing, the flow-volume display of this patient suggested an intrathoracic obstruction. The patient had a right aortic arch with ligamentum arteriosum that extended anterior to the trachea. This condition caused constriction when increased pulmonary blood flow, oxygen demand, and tracheal airflow and decreased intratracheal pressure from downstream turbulence distal to the tracheal ring occurred with exercise; combined, these factors produced wheezing and dyspnea.

Sinus disease

Sinus disease, especially in children, is associated with bronchial asthma and wheezing. Although the association is not strong in patients with CT evidence of mild sinus mucosal thickening, a scoring system developed by Newman et al showed that extensive sinus disease was correlated with a substantially higher extent of wheezing than that in patients with only mild thickening. Of 104 adults, 39% had extensive disease, as visualized on CT scans, which was correlated with asthma and peripheral eosinophilia. [54]

Gastroesophageal reflux

Cough, recurrent bronchitis, pneumonia, wheezing, and asthma are associated with gastroesophageal reflux (GER). [55, 56] The incidence of GER in patients with asthma ranges from 38% in patients with only asthma symptoms to 48% in patients with recurrent pneumonia. Scintigraphic studies performed after technetium-99m sulfur-colloid ingestion have shown radionuclide activity in the lungs the next day, but no causal relationship between reflux and asthma has been established. Nevertheless, evidence suggests that increased pulmonary resistance occurs with symptoms of reflux during acid provocation testing; as some have suggested, the changes may be sufficiently significant to produce clinically evident bronchoconstriction. [55]

Other conditions and factors

Other extrinsic conditions, such as lymphadenopathy from sarcoidosis or Hodgkin lymphoma of the upper mediastinum, can contribute to asthma. In addition, aspirin or NSAID hypersensitivity and reactive airways dysfunction syndrome may be mistaken for asthma. Misdiagnoses as refractory bronchial asthma has resulted in inappropriate long-term treatment with corticosteroids.

A significant history of smoking greater than 20-pack years should make the diagnosis of chronic obstructive pulmonary disease (COPD) a stronger consideration than asthma.

Consideration for alternative diagnoses should be given in all patients, and in particular in those older than 30 years and younger than 2 years with new symptoms suggestive of asthma. An absence of airway obstruction on initial spirometry findings should prompt consideration for alternative diagnoses and additional testing.

Differential Diagnoses