Differential Diagnosis for Left Upper Lobe Segmental and Subsegmental Pulmonary Embolism
- Single most likely diagnosis:
- Pulmonary thromboembolism (PTE) - This is the most likely diagnosis given the direct evidence of embolism in the left upper lobe segmental and subsegmental branches on the CT angiogram. The presentation is consistent with the blockage of blood vessels in the lungs by a blood clot.
- Other Likely diagnoses:
- Deep Vein Thrombosis (DVT) with pulmonary embolism - Often, pulmonary embolisms originate from clots in the deep veins of the legs or other parts of the body. The presence of a DVT could be a source of the embolism.
- Pulmonary infarction - This could be a consequence of the pulmonary embolism, especially if the embolism is large and causes significant obstruction to blood flow, leading to tissue death in the lung.
- Do Not Miss diagnoses:
- Saddle pulmonary embolism - Although the question specifies segmental and subsegmental involvement, a saddle embolism (which is a large clot straddling the bifurcation of the main pulmonary artery) could potentially extend into segmental branches and is life-threatening.
- Pulmonary artery tumor or thrombus from a tumor - While less common, a tumor could cause obstruction similar to a thromboembolism and would have significant implications for treatment.
- Septic pulmonary embolism - This could occur in the setting of an infected thrombus or as a complication of an indwelling catheter and would require antibiotic therapy.
- Rare diagnoses:
- Pulmonary vasculitis (e.g., Wegener's granulomatosis, Churg-Strauss syndrome) - These conditions could mimic pulmonary embolism by causing inflammation and obstruction of the pulmonary vessels but are much less common.
- Pulmonary artery aneurysm or pseudoaneurysm - These could potentially cause filling defects on imaging that might be mistaken for emboli but are rare.
- Foreign body embolism - This could occur in specific contexts (e.g., iatrogenic during medical procedures or in drug users) and would have a different treatment approach.
- Parasitic embolism (e.g., hydatid disease) - In endemic areas, parasitic diseases could cause embolic phenomena, although this is exceedingly rare in most populations.