Differential Diagnosis for Mosaic Pattern on CT Chest
The mosaic pattern on CT chest refers to a patchwork appearance of lung attenuation, which can be caused by various conditions. Here's a differential diagnosis, categorized for clarity:
Single Most Likely Diagnosis
- Chronic Thromboembolic Pulmonary Hypertension (CTEPH): This condition is a common cause of mosaic pattern on CT chest, characterized by uneven lung perfusion due to chronic thromboemboli in the pulmonary arteries. The mosaic pattern is due to areas of oligemia (reduced blood flow) adjacent to areas of normal or increased blood flow.
Other Likely Diagnoses
- Small Airway Disease: Conditions such as bronchiolitis or small airway asthma can cause a mosaic pattern due to air trapping and uneven ventilation.
- Pulmonary Veno-Occlusive Disease (PVOD): A rare condition characterized by occlusion of the pulmonary veins, leading to a mosaic pattern on CT due to uneven lung perfusion.
- Idiopathic Pulmonary Fibrosis (IPF): While IPF typically presents with a reticular pattern, some cases can exhibit a mosaic pattern due to fibrosis and honeycombing.
Do Not Miss Diagnoses
- Pulmonary Embolism (PE): Although less common, a large or multiple PEs can cause a mosaic pattern due to acute oligemia. Missing this diagnosis can be fatal.
- Pulmonary Arteriovenous Malformations (PAVMs): These abnormal connections between pulmonary arteries and veins can cause a mosaic pattern and are important to diagnose due to the risk of paradoxical embolism and brain abscess.
Rare Diagnoses
- Lymphangitic Carcinomatosis: Metastatic disease to the lung lymphatics can cause a mosaic pattern due to uneven lung perfusion and lymphatic obstruction.
- Neurofibromatosis Type 1 (NF1) with Pulmonary Involvement: A rare condition that can cause a mosaic pattern due to pulmonary neurofibromas and cystic changes.
- Histiocytosis X: A rare condition characterized by the proliferation of histiocytes in the lung, which can cause a mosaic pattern due to cystic changes and fibrosis.