Document jBnJy2J8NQpYvKKzKLwbk5DJQ

-13-2006 07:10P FROM: TO:1618259 UO SILICOSIS AND OTHER FJBROTlC PNEUMOCOMOShS as bli;o-black polygonal areas J-i inch in diameter. These are distributed over ho whole of the cut surface, but arc most evident in the lower lobes. This pay be due to confluence or simply to the greater bulk of the base of the lung. Anatomically it will be observed that these polygonal fibrosed areas conform to the size and shape of the pulmonary lobules, which they have, in fact, replaced. All' these changes may be considerably modified according to the terminal illness* broncho-pneumonia, tuberculosis, bronchial carcinoma or con' gestiye heart failure. Other organs do not show any characteristic changes, they are not involved in the disease save indirectly and in relation to complications and sequelae Microscopical up/iearances Asbestos fibres (natural and altered), plugs of mucus and desquamated epithelium may be observed in the maJn air-passages la ihu terminal bron chioles and alveolar ducts, these changes are more advanced and associated with the presence of large mononuclear phagocytes. The alveoli and lymphutio vessels are blocked with dust und phagocytes Connective tissue surrounds the bronchioles, alveolar ducts, air-sac$ and blood vessels, and penetrates into the interlobular septa and beneath the pleura. In the most advanced stage, all appearances of lung structure are obliterated by fibrous ! tissue, i j The ashestosis body I Curious bodies in the lungs were first described by Stuart McDonald in 1927. They are now recognized as a feature of exposure to the inhalation of asbestos fibres, and they have been identified in the lungs, pleura, sputum and faeces. It Is now accepted that they are formed from the original fibre by the following process: (1) deposition of some material around the fibre so as to thicken it; i (2) fissure or cracking of (his material giving rise to the appearance of 1 segments; (3) fragmentation, or the separating off from the asbestosis body j of fractured portions of the deposited material. Oioyne (1932) summarizes , the variety of uppearanees hs follows. j (1) Marked variation in length (24-60 microns) and breadth (12-24 p). Gardner and Cummings (1931) record thur being as long as 250 p in experi mental animals The short forms arc sometimes seen within phagocytes. (2) Golden yellow colour: Gardner and Cummings have pointed out the resemblance of this colour to the haemosidcrin deposits found in areas of tissue in which haemorrhage has occurred. (3) Homogeneous structure when viewed by ordinary transmitted light. | (4) By cutting down the light, a suggestion of a central fibre can often be j seen. This fibre may also sometimes be seen projecting beyond the body, i (5) No dilTcreniiarion with polarized light, i (6) Tendency to be arranged m irregular clumps and clusters