Diagnosis is made by serological detection of antibodies by ELISA, PCR, or indirect fluorescent antibody testing of suppurative material. Warn laboratory staff as handling precautions are necessary.

Tularaemia is a rare zoonosis caused by the bacterium Francisella tularensis. Skin, eyes, lymph nodes, and lungs are most commonly affected.

The chest imaging findings are variable but lymphadenopathy is the most common. Lung nodules, masses, and consolidation can also be present.

The primary differential diagnosis, in this case, is histoplasmosis. A detailed history of exposure, especially to wild animals, can help consider tularaemia. Her only known exposure to animals was a recent trip to a zoo (unlikely to be the source in the author's opinion). Tularaemia is considered a reportable disease in many jurisdictions.

Case courtesy of J. David Godwin, M.D. (Seattle WA)