Correct!
Answer: 2. Pulmonary alveolar proteinosis
All of the diagnoses mentioned above present as diffuse pulmonary opacities on thoracic CT, and all of these entities can cause a “crazy paving” pattern on thoracic CT. However, pulmonary alveolar proteinosis is the best explanation among those provided for a crazy paving pattern on thoracic CT in a patient with a subacute illness.
Patients with acute interstitial pneumonia (AIP) are often more acutely ill than this patient’s presentation suggests, and, while elements of a crazy paving pattern can be seen on thoracic CT performed for patients with AIP, often there is more heterogeneous opacity and frank consolidation present as well. Desquamative interstitial pneumonia is a rare disorder that occurs primarily in smokers, and the clinical history specifically states that this patient is a non-smoker. Acute eosinophilic pneumonia is a possibility, but such patients are usually previously healthy with a fairly abrupt onset of an acute, severe illness, not infrequently followed by respiratory failure, which contrasts with the slowly progressive nature of this patient’s illness. Lipoid pneumonia may clinically present in a subacute fashion and may show a crazy paving appearance on thoracic CT, but often a history of a causative agent- such as mineral oil use- can be uncovered with pointed questioning, and such a history was not mentioned in this case.
Which of the following represents the most appropriate next step in management at this point?