34 y.o. male with history of IVDA (intravenous drug abuse) complains of fever, chills and cough. Diagnosis?
Answer: Lung Abscess (from septic pulmonary emboli)
Lung Abscess
Necrosis of lung parenchyma with pus and debris-filled cavities
Caused by direct injury (e.g., aspiration pneumonia) or secondary causes (e.g., tricuspid endocarditis, bacteremia, etc.)
Suspect with:
Loss of airway reflexes (e.g., CVA, seizures, alcohol / narcotic abuse, etc)
Poor dentition
Immunosuppression
IVDA
Gram positives, negatives and anaerobic bacteria have all been implicated.
CXR may suggest diagnosis, but CT scan better identifies abscess, necrotic tissue, empyema, or other pathology (see image below).
After drawing blood cultures, broad-spectrum antibiotics should be started and narrowed once culture data is available; address underlying cause (e.g., valve replacement for endocarditis).
Prognosis is generally good with normal immune function and antibiotics, but mortality sharply increases with immunocompromise and treatment delay.
Mansharamani N, et al. Lung abscess in adults: clinical comparison of immunocompromised to non-immunocompromised patients. Respiratory Medicine. Mar 2002;96(3):178-85
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