Differential Diagnosis
- Single most likely diagnosis
- Pneumonia: The patient presents with chest pain that worsens with deep breathing, diarrhea, nausea, and a focal consolidation in the lingula on imaging, which strongly suggests pneumonia. The symptoms and imaging findings align closely with this diagnosis.
- Other Likely diagnoses
- Pulmonary infarction: Although the CTA did not show evidence of pulmonary embolism, the presence of chest pain and the finding of a small nodule could suggest a pulmonary infarction, especially if the initial CTA was done early in the course of the disease.
- Acute bronchitis: The patient's symptoms of chest pain, diarrhea, and nausea could also be consistent with acute bronchitis, particularly if the pneumonia diagnosis is not fully confirmed.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Pulmonary embolism: Despite the CTA showing no evidence of pulmonary embolism, this diagnosis should always be considered in patients with chest pain, especially if the pain worsens with deep breathing. The initial test could potentially miss small emboli.
- Cardiac ischemia: Although the troponin level is very low (0.01), cardiac causes of chest pain should always be considered, especially in patients with risk factors for coronary artery disease.
- Malignancy: The presence of a 4 mm nodule in the right lobe, although small, necessitates follow-up to rule out malignancy, especially if the nodule does not resolve with treatment for pneumonia.
- Rare diagnoses
- Pneumocystis jirovecii pneumonia (PCP): This could be considered in immunocompromised patients but would be less likely without additional risk factors.
- Eosinophilic pneumonia: This rare condition could present with similar symptoms but would typically require additional diagnostic testing, such as blood eosinophil counts or biopsy.
- Vasculitis (e.g., Wegener's granulomatosis): Although rare, these conditions can present with pulmonary symptoms and should be considered if other diagnoses are ruled out and the patient's condition does not improve with standard therapy.