A farmer with chest pain and lung nodules
A 50-year-old farmer reports having bilateral pleuritic chest pain for the past week. He was treated 25 years ago for brucellosis, with neither clinical nor radiologic lung involvement. He is a 30-pack-year smoker. He lives in a rural area. He reports no other symptoms.
The physical examination is normal except for mild hepatomegaly. Laboratory tests (including transaminases) were normal, with the exception of the C-reactive protein level (7 mg/dL). Tumor markers, beta-2-microglobulin level, serologic tests for atypical bacteria and Brucella organisms, Mantoux test, protein electrophoresis, and tests for autoimmune antibodies were normal or negative. Echocardiography revealed no vegetations. However, chest radiography revealed multiple nodules in both lungs (Figure 1, arrows). Thoracic computed tomography showed well-defined nodules 2 to 3 cm in diameter suggestive of calcified granuloma (Figure 2, arrows).
Q: Which is the most likely diagnosis?
- Pulmonary tuberculosis
- Metastatic lung disease
- Pulmonary brucellosis
- Septic pulmonary emboli
- Lymphoma
A: The most likely diagnosis is pulmonary brucellosis. The patient lives in a rural area where brucellosis is endemic, and his occupation has meant that he also has had decades of daily exposure to farm animals, mainly sheep.
Lung biopsy specimens were obtained by minimally invasive thoracoscopy (Figure 3), and histologic study revealed noncaseating granulomas with central necrosis (Figure 4). Lastly, cultures of the resected nodule were positive for Brucella melitensis.
Once the diagnosis of pulmonary brucellosis was made, the following treatment regimen was started: rifampicin 600 mg daily for 2 months, doxycycline 100 mg twice daily for 2 months, and intramuscular gentamicin 240 mg daily for 2 weeks. The chest pain gradually improved and resolved completely by 1 month after treatment was started; the lung lesions disappeared 8 weeks later. The patient remains disease-free at 6 months.
