[Frequency, morphology, pathogenesis and complications of silicotic callosities (phthisis atra). A disappearing disease].

Over a period of approximately 30 years we have compared the frequency of Miner's phthisis in the coal mining areas of Aachen and the Ruhr area of Essen and have investigated a total of approximately 600 lungs with silicosis. In cases of silicosis grades II-III and III we found liquefaction in 36% of the callosities but in cases of silicosis I-II and II in only 4-7%. Liquefaction of callosities, or phthisis atra, was found slightly more often in the Ruhr area than in the area of Aachen. If the liquefied silicotic material is expectorated from the bronchial tubes, a cavern-like cavity develops in the lungs, which clinically can often not be differentiated from a tuberculotic cavern. Sometimes silicotic material is transported via the blood vessels and dust particles could often be found microscopically in the liver, spleen or kidneys. In one patient we found silicotic material coming from the bronchial veins with development of arterial embolisms in peripheral arteries of the extremities and brain. The pathogenesis of callosity liquefaction is a consequence of disruption of the blood supply to the surrounding areas of the callosities. In some cases blood vessels in the centre of the callosities are destroyed so that the patient dies after severe haemoptysis.