Clearance of asbestos bodies from the lung: a personal view.

In histological sections asbestos bodies in human lungs may be either transparent, yellow, strongly Perls-positive structures as described in published reports, or opaque, black structures, the ferroprotein coating having been converted into haemosiderin. The transparent asbestos bodies fragment into segments; the black asbestos bodies disintegrate into a mass of haemosiderin granules that accumulate as dense deposits, particularly near to blood vessels. The presence of haemosiderin granules indicates that asbestos bodies have broken down. When a patient has died with a mesothelioma there is little evidence of phagocytic activity in many areas of the lung. When exposure to asbestos ceased many years before a mesothelioma developed there may be few recognisable asbestos bodies remaining in the lung.