A 31 yo male with a history of hepatitis C, IV drug use, and homelessness presents with an influenza-like illness.  He complains of 2 days of fever, cough, malaise and sharp chest pain.  Chest x-ray shows bilateral nonspecific opacifications.  A chest cat scan is shown below.  What's the diagnosis?  (scroll down for answer) 

Answer:  Septic Pulmonary Emboli

• Varying sized nodular or cavitary lesions are seen on cat scan and less commonly on plain x-ray
• Patients may have minimal symptom burden, so high index of suspicion is warranted in the immunocompromised, IV drug users, and patients with indwelling devices (PICC lines, grafts, pacemakers)
• Common embolic sources: tricuspid valve vegetations, infected DVT, periodontal disease
• Work-up includes echocardiogram and blood cultures
• Treat with antibiotics, source control, and occasionally surgical drainage
• Emboli can travel elsewhere - pursue neurologic, abdominal and extremity evaluations when clincally indicated 

References:

https://radiopaedia.org/articles/septic-pulmonary-emboli

https://www.uptodate.com/contents/complications-and-outcome-of-infective...

Li Zhao RY, Wang C, Wu X, Yan H.  Clinical characteristics of septic pulmonary embolism in adults: A systematic review.  Respiratory Medicine. 2013; 108(1):1-8.