Pulmonary Alveolar Proteinosis
Discuss several unusual and uncommon pulmonary disorders.
Describe clinical manifestations and facilitate recognition of these disorders.
Discuss management options for these disorders.
Rare or “orphan” disease is defined as a disease or condition affecting <200,000 persons in the United States (Office of Rare Diseases, National Institutes of Health). An estimated 25 million people in the United States have one of the more than 6,000 rare diseases. The failure to diagnose a rare or unusual disease is generally due to a failure to consider the diagnosis in the initial evaluation. Thus, the diagnosis of unusual pulmonary disorders is facilitated by considering a broad differential diagnosis at the outset and the ability to recognize characteristic clinical context and imaging features that may be associated with these disorders. Histopathologic study can be helpful but more often than not needs to be correlated with the clinical and radiologic findings in reaching the correct diagnosis without which rational treatment and accurate prognostication are unlikely. Herein, six uncommon to rare pulmonary diseases are discussed—pulmonary alveolar proteinosis, pulmonary amyloidosis, Birt-Hogg-Dubé syndrome, IgG4-related disease, constrictive bronchiolitis, and spontaneous pneumomediastinum. These disorders are associated with characteristic clinical and imaging features that can allow a diagnosis in the absence of histopathology for some of these disorders.