A 52-year-old woman was admitted to
the hospital with progressive shortness
of breath of 2 days' duration. Bronchial
asthma had been diagnosed 6 months
earlier; inhaled corticosteroids, bronchodilators,
and leukotriene antagonists
were prescribed. Despite aggressive
treatment, the patient's dyspnea
and wheezing worsened.
The patient denied allergy, fever,
chills, rigors, hemoptysis, and chest
pain. She did not smoke cigarettes or
use alcohol. Three years earlier, she
had undergone surgery for colon cancer;
the patient has had no recurrences,
and there are no known metastases.
The patient was in obvious distress;
respiration rate was 26 breaths
per minute with the use of accessory
muscles. She was afebrile; pulse rate
was 88 beats per minute; blood pressure,
120/80 mm Hg. No clubbing or
cyanosis was noted. Heart sounds were
normal and without murmurs. Bilateral
wheezing, which was more prominent
on the right side, was heard on
auscultation. The abdominal and
neurologic examination findings were
White blood cell count was
11,200/μL with 72% neutrophils, 21%
lymphocytes, and 7% monocytes. Hemoglobin
level was 12.7 g/dL; hematocrit,
32%. The blood gases on room
air were pH, 7.44; PCO2, 30 mm Hg;
and PO2, 72 mm Hg. Forced vital
capacity (FVC), 96% of predicted;
forced expiratory volume in 1 second
(FEV1), 72% of predicted; and
FEV1:FVC ratio, 65. There was no
significant bronchodilator response.
The carbon monoxide-diffusing capacity
was 72% of predicted.
A chest film revealed hyperinflation
on the right side (Figure 1); infiltrate,
effusions, and lymphadenopathy were
absent. Because of the unilateral wheezing
and the failure of conventional antiasthma
medication, a bronchoscopy
was performed. The procedure demonstrated
a normal trachea and normal
left main bronchus; however, an endobronchial
polypoidal lesion was found
on the right main stem bronchus (Figure
2). A brush biopsy of the lesion revealed
a poorly differentiated adenocar-
cinoma that was most likely a metastatic
lesion arising from the prior colon
Following resection of the tumor,
the patient's wheezing and dyspnea
Keep in mind that "all that
wheezes is not asthma."1 As in this
patient, endobronchial lesions that
cause airway obstruction may be misdiagnosed
as asthma. This case offers
clues and strategies to help you
differentiate between asthma and
other causes of wheezing.
Asthma. The differential diagnosis
of asthma is one of the most
difficult problems in clinical medicine.
Although traditionally asthma
conjures images of paroxysms of
wheezing, shortness of breath, and
cough, the disease's presentation
can be deceptive. Asthma may present
as uncontrolled cough or dyspnea
alone; most patients have
wheezing as well.
Wheezing is usually absent
when the asthmatic process is in remission.
It is occasionally absent in
severe attacks, presumably because
the patient is not able to generate sufficient
airflow velocity to produce
wheeze. Conversely, wheezing may
be a prominent manifestation of numerous
nonasthmatic conditions of
the lung (Table 1). These pseudoasthmatic
syndromes respond poorly
to standard antiasthma therapy;
however, specific therapy directed
at the underlying disease is often
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