Differential Diagnosis for 74F with Fever, Cough, and Left Upper Lobe Opacity
- Single Most Likely Diagnosis
- Pneumonia: Given the patient's symptoms of fever and cough along with the left upper lobe opacity on chest X-ray, pneumonia is a highly likely diagnosis. The patient's recent immunotherapy with atezolizumab could also predispose her to infections.
- Other Likely Diagnoses
- Progression of small cell lung cancer: The patient's history of small cell lung cancer and recent treatment with atezolizumab make it possible that the left upper lobe opacity could represent progression of her underlying disease.
- Immune-related adverse event (irAE) from atezolizumab: Atezolizumab can cause irAEs, including pneumonitis, which could present with similar symptoms and radiographic findings.
- Reactivation of latent TB: Although the patient is on treatment for latent TB, reactivation is possible, especially in an immunocompromised state.
- Do Not Miss Diagnoses
- Pneumocystis jirovecii pneumonia (PCP): Given the patient's immunocompromised state due to cancer and immunotherapy, PCP is a critical diagnosis not to miss, as it can be life-threatening if not promptly treated.
- Invasive aspergillosis: This fungal infection can present similarly to bacterial pneumonia and is particularly concerning in immunocompromised patients.
- Rare Diagnoses
- Other opportunistic infections (e.g., cytomegalovirus, Legionella): While less common, these infections should be considered in the differential diagnosis of an immunocompromised patient with respiratory symptoms.
- Pulmonary embolism: Although the presentation is atypical, pulmonary embolism could cause fever and cough, and the left upper lobe opacity could represent an infarct.