Cholesterol in the lungs of heavy cigarette smokers.

Electron microscopy of "normal" lung tissue from four heavy cigarette smokers showed acicular crystal clefts thought to represent cholesterol in the cytoplasm of virtually every type II pneumocyte. Similar but less pronounced changes were found in two cases of obstructive pneumonia distal to bronchial tumours, a condition characterised by excess cholesterol. Cholesterol pneumonitis is particularly prevalent in smokers, and the changes in our smokers' lungs possible represent an early stage in a process that if progressive would lead to this disease. The cholesterol may represent a degenerative change in type II pneumocytes or a byproduct of increased surfactant synthesis stimulated by cigarette smoke.