Sarcoidosis...?

Today, Dr. Amrock presented an interesting case presentation with a diffuse HPI and poorly localizing signs and symptoms for which the diagnostic concern centered around evidence of granulomatous inflammation, hilar lymphadenopathy, uveitis, and possible infiltrative cardiomyopathy concerning for sarcoidosis. The patient underwent BAL with testing sent for analysis of the CD103/CD8 ratio that was potentially suggestive of pulmonary sarcoidosis. Some takeaways:

  • The published sensitivity and specificity of the CD103/CD8 ratio in BAL washings for the diagnosis of sarcoidosis was 81% and 78% respectively, which gives a +LR of 3.68 and 0.24 respectively. Which means the positive test should raise our pretest probability of the diagnosis of sarcoidosis ~20-25% (link to my favorite sensitivity/specifity to likelihood ratio converter).
  • Sarcoidosis is a multisystem disorder of unknown etiology that is characterized pathologically by the presence of noncaseating granulomas in involved organs
  • A definitive diagnostic test does not exist. The diagnosis of sarcoidosis requires three elements: 1) Compatible clinical and radiographic manifestations 2) Exclusion of other diseases that may present similarly 3) Histopathologic detection of noncaseating granulomas.