Differential Diagnosis for Alveolar Proteinosis with Cobblestoning on CT
Single Most Likely Diagnosis
- Pulmonary alveolar proteinosis (PAP): The presence of cobblestoning on CT, which refers to a pattern of ground-glass opacification with interlobular septal thickening, is consistent with PAP. This condition is characterized by the accumulation of surfactant-like protein and phospholipids within the alveoli, leading to respiratory symptoms.
Other Likely Diagnoses
- Pneumocystis jirovecii pneumonia (PCP): This opportunistic infection can present with similar radiographic findings, including ground-glass opacities and interlobular septal thickening, particularly in immunocompromised patients.
- Acute respiratory distress syndrome (ARDS): While more commonly associated with a clinical context of severe illness, ARDS can present with diffuse ground-glass opacities on CT, which might resemble cobblestoning in some cases.
- Cryptogenic organizing pneumonia (COP): COP can manifest with a variety of radiographic patterns, including ground-glass opacities, and might be considered in the differential, especially if other findings such as bronchiectasis or nodules are present.
Do Not Miss Diagnoses
- Invasive pulmonary aspergillosis: Although less likely, this diagnosis is critical not to miss due to its high mortality rate, especially in immunocompromised patients. It can present with similar radiographic findings, including ground-glass opacities and cavitation.
- Mucormycosis: Another opportunistic infection with high mortality, mucormycosis can cause pulmonary disease with nonspecific radiographic findings, including ground-glass opacities and nodules.
Rare Diagnoses
- Lymphangitic carcinomatosis: A rare condition characterized by the spread of cancer to the lymphatic vessels of the lung, it can present with interlobular septal thickening and ground-glass opacities, mimicking the cobblestoning pattern.
- Niemann-Pick disease: A group of rare genetic disorders that can lead to accumulation of sphingomyelin in various organs, including the lungs, potentially causing radiographic patterns similar to alveolar proteinosis.
- Pulmonary alveolar microlithiasis: A rare disease characterized by the presence of small calculi within the alveoli, it can present with a "sandstorm" appearance on radiographs but might show ground-glass opacities on CT in some cases.