Monday, April 13, 2009

Day #278 - Cavitary Lung Lesion


Today we heard the case of a young man with a history of constitutional symptoms (sweats, weight loss) in association with a non-productive cough and a cavitary right upper lobe infiltrate.

I have previously blogged about the differential of cavitary lung lesions

Based on the presentation I favor an infectious etiology, most likely tuberculosis. The absence of AFB on the bronchoscopy does *not* mean this isn't tuberculosis.

This study of 230 cases of culture positive pulmonary tuberculosis showed that the BAL AFB stain was only positive in 48/95 patients without spontaneous sputum production. In this study, the sensitivity of BAL AFB stain was better, but still only 70%.

The take home message is that a negative smear does not exclude TB in a compatible case. Repeat samples are sometimes indicated and awaiting the final culture is also required. In this case I would add induced sputum daily in the AM for three days to maximize my chances of making the diagnosis.

This article reviews the various radiographic manifestations of pulmonary tuberculosis.

Treatment of Pulmonary TB (see Canadian Tuberculosis Standards):
Initial:
  • Isoniazid (INH) +/- Vitamin B6
  • Rifampin (RIF)
  • Pyrazinamide (PZA)
  • Ethambutol (ETH)
If demonstrated susceptible to INH/RIF/PZA:
  • Can stop ETH immediately
  • Continue INH/RIF/PZA until 2 months then stop PZA
  • Continue INF/RIF 4 months to complete 6 total months

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