We describe the case of a heavy marijuana and tobacco smoker who presented
with progressive exertional dyspnea of 2 months' duration, and bilateral no
dular lung infiltrates. Examination of the lung fields was normal, and lung
function tests showed mild airflow obstruction with moderately reduced gas
transfer. BAL returned green-black fluid consisting predominantly of macro
phages laden with carbon pigment. Thoracoscopic lung biopsy showed miliary
necrotizing granulomata with an alveolar exudate of carbon-laden macrophage
s within macroscopically blackened lung. The differential diagnosis of pulm
onary granulomata in this patient is discussed.