ZSFG AM Report Pearls 1/30/18: I Got, I Got Loyalty, Got Royalty in My TB Pleurisy

OK, I know that doesn’t perfectly rhyme. Thank you to Kendra and Nathan for presenting an outstanding case of a patient with a recurrent pleural effusion, found to have calcified granulomas in the bilateral upper lobes, and a high suspicion for TB pleurisy.

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Tuberculous Pleural Effusion (i.e. TB Pleurisy):

Epidemiology:
  • Globally, MTB is the most common cause of pleural effusion!
  • Extrapulmonary TB accounts for about 25% of the initial presentations, most frequently involving lymph nodes and pleura
Diagnosis:
  • Gold Standard: detection of M. tuberculosis in sputum, pleural fluid, or pleural biopsy specimens either by microscopy and/or culture or histological demonstration of caseating granulomas in the pleura along with AFB
  • Often, diagnosis is inferred in patients who present with a lymphocytic predominant exudate + high ADA level
Sputum:
  • It is important to obtain cultures on induced sputum samples, even in the absence of obvious parenchymal involvement.
  • At this time, there are no studies evaluating the role of sputum nucleic acid amplification (NAA) molecular studies such as Xpert MTB/RIF in the context of TB pleural effusions.
    • NAA tests may increase the diagnostic yield of sputum compared with conventional microscopy, but is unlikely to be more sensitive than culture
Thoracentesis/Pleural Studies:
  • Uniformly exudative effusions, typically with >50g/L of protein, LDH elevated in 75% of cases (typically >500)
  • ADA: Wide range of cut-offs but the higher the value the more liekely.
    • Accurate threshold in variety of studies suggests 40-60 U/L
    • Note that the local prevalence of TB greatly affects the performance of the ADA test
      • Specifically, in low prevalence areas/population, a negative test can be pretty good at ruling out TB
 
Pleural Biopsy
  • Presence of caseating granulomas with AFB on histological exam is a SLAM dunk, although seeing AFB is not required in high burden areas
  • The more biopsies the higher the sensitivity, and performing with thoracoscopy greatly increases the sensitivity
Tuberculous Pleural Effusion
Evernote:
Source:
Vorster MJ et al. (2015). Tuberculous pleural effusions: advances and controversies. Journal of Thoracic Disease. 7(6):981-991.
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