Thank you to all faculty and residents who participated in this morning’s very interesting AM report on chronic pulmonary Coccidioidomycosis.

Differential diagnosis of cavitary lung lesions:

• Fungi
  • Coccidioides (southwest US, northern Mexico, parts of Central and South America)
  • Aspergillus
  • Histoplasmosis (boards: Ohio-Mississippi river valleys. But also in other parts of US, Mexico, Central and South America)
  • Blastomycosis (boards: Ohio-Mississippi river valleys/Midwest, Southeast. Occasional cases in Mexico, Central and South America)
  • Cryptococcus
• Tuberculosis
• Non-TB mycobacterium
• Lung abscess (air-fluid levels within cavitation on imaging)

Coccidioides Serology Interpretation:

• Serology for IgM and IgG typically ordered first (as they are the most sensitive tests in early infection)
• If IgM or IgG are positive, then next tests are immunodiffusion (as it is the more specific test and positive immunodiffusion is diagnostic of cocci) and complement fixation (CF; generally, higher titers are correlated with disease severity and changes in serial titers with treatment can be used prognostically)
• Serologies may be negative in early disease as antibodies can take weeks after infection to develop, so repeat testing several weeks later is appropriate if high clinical suspicion/pretest probability remains for Cocci despite negative initial serologies.