Differential Diagnosis for Mosaic Attenuation on CTA
Single Most Likely Diagnosis
- Chronic Thromboembolic Pulmonary Hypertension (CTEPH): Mosaic attenuation on CT angiography (CTA) is often indicative of unequal blood flow to different areas of the lungs, which can be seen in CTEPH due to chronic clots obstructing pulmonary arteries, leading to areas of oligemia.
Other Likely Diagnoses
- Pulmonary Embolism (PE): While not as chronic as CTEPH, acute PEs can also cause mosaic attenuation by obstructing blood flow to certain areas of the lung.
- Pulmonary Arterial Hypertension (PAH): PAH can lead to pruning of the pulmonary arteries, resulting in areas of decreased attenuation due to reduced blood flow.
- Bronchiectasis: This condition involves dilation of the bronchi and can lead to areas of decreased lung perfusion, manifesting as mosaic attenuation.
Do Not Miss Diagnoses
- Pulmonary Venous Occlusive Disease (PVOD): A rare condition that can mimic other diseases but is critical to diagnose due to its poor prognosis and different treatment approach.
- Pulmonary Arteriovenous Malformations (PAVMs): These can cause uneven blood flow and may present with mosaic attenuation; missing this diagnosis could lead to significant morbidity due to paradoxical embolism or other complications.
Rare Diagnoses
- Histiocytosis X (Langerhans Cell Histiocytosis): Can cause a variety of pulmonary findings, including mosaic attenuation, due to the infiltration of Langerhans cells into the lung parenchyma.
- Neurofibromatosis Type 1 (NF1) with Pulmonary Involvement: Rarely, NF1 can involve the lungs, leading to findings such as mosaic attenuation due to vascular or parenchymal disease.
- Pulmonary Capillary Hemangiomatosis (PCH): An extremely rare condition characterized by capillary proliferation within the lung, which can lead to pulmonary hypertension and mosaic attenuation on imaging.