Differential Diagnosis for Right Middle Lobe Infiltrate
- Single Most Likely Diagnosis + Community-acquired pneumonia (CAP): This is the most common cause of a lobar infiltrate, and the right middle lobe is a typical location for pneumonia. The presentation is often with fever, cough, and sputum production.
- Other Likely Diagnoses + Pulmonary embolism with infarction: Although less common than pneumonia, pulmonary embolism can cause a lobar infiltrate, especially if there is associated infarction of the lung tissue. Symptoms may include sudden onset of chest pain and shortness of breath. + Bronchitis or bronchiolitis: Inflammation of the bronchi or bronchioles can lead to an infiltrate on imaging, particularly in the setting of an infectious or inflammatory process. + Allergic bronchopulmonary aspergillosis (ABPA): This condition occurs in asthmatic patients and can cause infiltrates due to an allergic reaction to Aspergillus species.
- Do Not Miss Diagnoses + Tuberculosis (TB): Although less common in some regions, TB can present with a lobar infiltrate and must be considered, especially in high-risk populations or those with exposure history. + Lung cancer: A new infiltrate could be the presentation of an underlying malignancy, particularly if there are risk factors such as smoking. + Sarcoidosis: This autoimmune disease can cause lung infiltrates and should be considered, especially if there are other systemic symptoms or findings suggestive of sarcoidosis.
- Rare Diagnoses + Eosinophilic pneumonia: A rare condition characterized by an accumulation of eosinophils in the lungs, which can cause infiltrates. + Lymphoma: Both Hodgkin and non-Hodgkin lymphoma can involve the lungs and cause infiltrates, though this is less common. + Wegener's granulomatosis (Granulomatosis with Polyangiitis): A rare autoimmune disorder that can cause lung infiltrates among other systemic manifestations. + Cryptogenic organizing pneumonia (COP): A rare condition of unknown cause characterized by lung inflammation and scarring, which can present with infiltrates on imaging.