Suspect in patients with fever & cough. Physical Exam: Focal rales (inspiratory crackles).
Chest x-ray is sensitive for the diagnosis; rare false-negatives in the first 24 hours.
But specificity is not guaranteed; small infarctions from PE’s can mimic pneumonia. Be cautious diagnosing pneumonia in the absence of cough and fever, unless the infiltrate is large, or the patient debilitated.