An 8-year-old boy presented with a 6-week history of shortness of breath, cough, and myalgias, but no fever. His pediatrician had made the diagnosis of bronchiolitis, and the patient was treated with azithromycin and albuterol via a metered-dose inhaler. Because the patient did not improve, he was given a 10-day course of amoxicillin, followed by a course of clarithromycin after a chest radiograph revealed bilateral infiltrates, suggesting atypical pneumonia.
The patient had no history of asthma, pneumonia, or recurrent otitis media. His sister received a diagnosis of bronchiolitis at the time of his diagnosis, but she improved after a course of azithromycin. His environmental history included the presence of dogs, a cat, a parakeet, and fish in the family home.
The patient and his family traveled to Mexico on vacation, by the end of which the patient's symptoms had improved. However, on the night that he returned home, he experienced dyspnea and cough. Hypoxia (oxygen saturation, 88%) was documented in the emergency department, and he required the administration of oxygen via nasal cannula at a rate of 0.25 L/min.
Chest auscultation revealed basilar crackles without wheezing. There was no evidence of club- bing or lymphadenopathy. Findings from a cardiac examination were negative. The patient denied any GI symptoms.
A chest radiograph showed bilateral perihilar and basilar infiltrates (Figure 1). Because of these findings and the presence of hypoxia (despite 3 courses of antibiotics), the patient was admitted to the pediatric department and the pediatric pulmonary service was consulted.
A high-resolution CT scan of the chest showed a diffuse ground-glass pattern with micronodules (Figure 2). Flexible bronchoscopy and bronchoalveolar lavage (BAL) demonstrated a nonerythematous tracheobronchial tree. Histopathologic results revealed 10% macrophages and 90% neutrophils. Cultures of BAL fluid were negative for bacteria, viruses, and fungi. The patient refused pulmonary function tests.
Results of a hypersensitivity panel for IgG antibodies, available a few weeks later, demonstrated high levels of IgG antibodies to bird feathers and pigeon droppings. Results of a sweat chloride test and immunoglobulin levels were normal. Based on clinical and radiologic findings, an initial diagnosis of hypersensitivity pneumonitis was made and was supported by the positive results for precipitating IgG antibodies.
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