Abstract
Black pigments deposited in the lung may be the indicator of environmental pollution during one's life. These pigment foci increase their number age by age, and are seen more abundantly in the man's lung than in the woman's lung. The correlation between these pigment deposits and pathological changes of bronchopulmonary system was studied on 196 autopsy cases died of the diseases other than respiratory disease. After macroscopic observation, more than four parts of the lung, i. e., S1a, S2b, S9 and the lower lobe main bronchus, were examined histologically, and the relation between the degree of pigmentation and the frequency or severity of each pathologic change was studied.
The pigmented foci appear usually after 20 years of age, and increase their number after 40 years of age, especially after 60 years of age. These pigmentations are seen most in the apex and S2a, then in S2b, S6 and S3, and rare in the basal part of the lung. Squamous cell metaplasia and basal cell hyperplasia of bronchial- or bronchiolar epithelium seemed to have some relation with the black pigment deposit, and these changes are more frequent and severe in the lung of marked pigmentation. But, hyperplasia of mucous glands or goblet cells in bronchial or bronchiolar walls did not show any relation to the amount of pigment deposit, as well as the cell infiltration of bronchial or bronchiolar wall. Fibrous thickening of bronchiolar walls and small scar tissues scattered in the lung had some relation with the degree of pigmentation, and emphysema (mainly centrilobular emphysema) seemed to have relation with the deposition of black pigments.
Although our series contain only a few cases which had been diagnosed as chronic bronchitis clinically, it can be thought from these observations that an inhalation of the polluted air stimulates the bronchiolar wall and causes chronsc bronchiolitis, bronchiolopneumonia and sometimes centrilobular emphysema on one hand, and causes deposition of black pigments in the lung on the other hand.
