Differential Diagnosis for Patient with Autoimmune Disease and Abnormal Pulmonary Function Tests
Single Most Likely Diagnosis
- Sarcoidosis: This condition is a common autoimmune disease that can cause pulmonary function abnormalities, including increased FVC and FEV1, but may also lead to low Peak Inspiratory Flow (PIF) due to upper airway involvement or other mechanisms.
Other Likely Diagnoses
- Rheumatoid Arthritis (RA) with Pulmonary Involvement: RA can cause various pulmonary manifestations, including interstitial lung disease, which might result in increased lung volumes (FVC and FEV1) in some cases, and low PIF due to airway involvement or muscle weakness.
- Systemic Lupus Erythematosus (SLE) with Pulmonary Involvement: SLE can affect the lungs in several ways, potentially leading to increased FVC and FEV1, and low PIF due to diaphragmatic weakness or other pulmonary complications.
- Myasthenia Gravis: This autoimmune disease causes muscle weakness, which can affect the diaphragm and other respiratory muscles, leading to low PIF, and potentially increased FVC and FEV1 if the patient is able to perform the maneuver with sufficient force.
Do Not Miss Diagnoses
- Thymoma: Although rare, thymoma is associated with myasthenia gravis and can cause respiratory symptoms due to local compression effects or paraneoplastic syndromes, making it crucial not to miss.
- Pulmonary Embolism: While not directly related to autoimmune diseases, pulmonary embolism can cause sudden changes in pulmonary function and must be considered in any patient with new or worsening respiratory symptoms.
Rare Diagnoses
- Eosinophilic Granulomatosis with Polyangiitis (Churg-Strauss Syndrome): A rare autoimmune condition that can affect the lungs and cause various pulmonary function abnormalities, including those described.
- Relapsing Polychondritis: This rare disease can cause inflammation of the cartilaginous structures, including those in the trachea, potentially leading to abnormal pulmonary function tests, including low PIF.