Differential Diagnosis

• Single most likely diagnosis
  • Tuberculosis (TB): The patient's positive PPD test with 11 mm of induration, chest x-ray showing lymph node enlargement, and lesions in the lower lobes of the lungs are all consistent with TB, especially in an immunocompromised individual such as an alcoholic.
• Other Likely diagnoses
  • Sarcoidosis: This condition can cause lymph node enlargement and pulmonary lesions, and can also cause a false-positive PPD test due to anergy.
  • Fungal infections (e.g. histoplasmosis, coccidioidomycosis): These infections can cause similar pulmonary and lymph node findings, and are more common in immunocompromised individuals.
  • Lung cancer: The patient's history of alcoholism and age increase the risk of lung cancer, which can cause lesions in the lungs and lymph node enlargement.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Lymphoma: Although less likely, lymphoma can cause lymph node enlargement and pulmonary lesions, and is a potentially life-threatening condition if not diagnosed and treated promptly.
  • Metastatic cancer: Similar to lymphoma, metastatic cancer can cause lesions in the lungs and lymph node enlargement, and is a potentially life-threatening condition if not diagnosed and treated promptly.
• Rare diagnoses
  • Silicosis: This occupational lung disease can cause lymph node enlargement and pulmonary lesions, but is less likely in this patient without a known history of exposure to silica.
  • Berylliosis: This rare lung disease can cause lymph node enlargement and pulmonary lesions, but is less likely in this patient without a known history of exposure to beryllium.