Document QJgz8jryoM6z921ObRR3w6qgk

376 0. A. SANDEK showed no evidence of fibrosis or other cellular response. The same has fc shown to be true for barium and tin deposits.48 Gross examination. Except with prolonged and intensive exposure, pleural surfaces of lungs with benign pneumoconiosis show only focal and line collections of pigment that are soft in consistency and not raised above the rounding tissues. On cut-surfaces, gross examination reveals rounded flecks of pig ment 2 to 3 mm. in diameter, but a lens shows finer linear deposits in the : lobular septa and in the outer walls of the blood vessels. The entire lung m; colored by pigment as in the black lung of soft-coal miners, but no fibrosis is foi unless there has been exposure to free silica. There may be small patches of physema in or adjacent to pigmented areas. Scars of healed infections differ frc the usual scars by the presence of pigment. Microscopic examination. If death occurs during exposure, dust particles'a! found free in the peripheral air spaces or ingested by alveolar phagocytes that ar found adherent to alveolar walls and in loose areolar tissue about the blood vessel' especially the arteries, and in the interlobular septa. These last two linear depo^ are referred to as perilymphatic deposits because of their close relationship tojjb lymphatic trunks. The bronchi show relatively little dust; when any is prese however, it is found in the connective tissues just beneath the epithelium. If i has been no recent exposure (years), the intrapulmonary dust tends to be rem$v from the air spaces and deposited along the lymph trunks; in severe exposure 1 " amounts of dust-filled phagocytes may remain in the alveoli. Nearly all'll Lubstancesjother^than_SALicfL,Cfluae_li.Ule_cellularJceactioti_GaaLand-some-siliP; especially mica, may cause minor irritation without producing fibrosis. Unlesll linear reaction is fibrous and caused by free silica, there is no altered suscepti&if to tuberculosis. b. Discrete Nodular Silicosis: X-ray examination. This form of dust disease characterized in the x-ray film by enlarged and dense hilum shadows and discrete nodular shadows, uniformly distributed throughout all parts of both 1 with the possible exception of small emphysematous , areas-in the costoph'ffnr region. In the absence of infection, the nodules are of uniform size, usually^ exceeding 4 mm. and seldom more than 6 mm. in diameter. The nodules are i with well-defined borders (see Figure 6). tf ___ Gross examination. The pleurae..are studded with alightLy^ele-vAtedr-gf^l nodules 2to :3 vHams? lift'diameter, and around these there may-be a flatzdni black, gray, or br'ovhi'jjfgment. Pleural adhesions may or may not be present;'!, lungs are stiffer than normal but crepitus is present. There are palpable nodules. The cut surfaces are seeded with black or gray nodules, 2 to 4 mm5 " A. Arrigoni, Pneumoconioai da bario, Med. d. lavoro, 24-, 461-468 (1933); E. P. Pen$jS* grass, Roentgen diagnosis of pneumoconiosis and silicosis, Am. J. Roent. and Rad. Ther., 4k, 571-594 (1942) (Baritosis, p. 580); E. P. Pendergrass and A. W. Pryde, Benign pneumoconiop due to tin oxide, J. Ind. Hyg. Toxicol., .30, 119-123 (1948); F. Bartak, M. Tomecka, and ft TomiSek, Stannosis, Casop. 16k. cesk, 87, 915-932 (1948); C. C. Dundon and J. P. Hughf Stannic oxide pneumoconiosis, Am. J. Roent. and Rad. Ther., 63, 797-812 (1950). PULMONARY DUST DISEASES 377 fe e. Classical nodular silicosis of moderately well-developed degree in sandstone wheel linder. Only slight shortness of breath on exertion. Note large and dense root shadows. J| "|iy 6 mm., in diameter. The edges of the nodules are well defined, but a lens ^pigmented strands radiating from their periphery. There is little confluence ^(fewhere scars or infection are present. Gross emphysema may or may not be |t, but this condition may be apparent only with microscopic examination. ISerentiation-from-perilymphatio-pigmen-tation-there-must be definite-pleural Jffion in an appreciable amount. Some nodules may arise along the jjenphera'l ggiijpss of the pulmonary arteries. The tracheobronchial lymph nodes are at first JWged and firm, later smaller and extremely hard. Sections of these nodes reveal % leatherlike tissue, which is silky in texture because of the decrease in l||enous connective tissue. icroscopic examination. Microscopic examination. shows layers of dense Sfipe.collagenous fibers with nuclei so compressed as. to e-almost invisible at p! The borders are clear cut, with no exudation. There may be pigment either put the periphery or in focal points within the nodule itself. The nodule may be fed, occasionally to the point of bone formation in its central portion. Nearly ^p-lesAre associated-with-branches`Of-th'eVpulm6nary'-ar-teries,-as demonstrated ffax^reconstruction of the arteries; they may form spherical or spindle-shaped Sills around the arteries. Pigmentation occurs about the lymphatic trunk just '^nonspecific pneumoconiosis, but there i3 always some fibrosis. The air spaces Stately adjacent.to.the.nodules are. distorted, and.frequently dilated,..There $ffbr may not be emphysema. The alveolar walls between nodules may Be entirely normal. & Modified Silicosis. Modified nodulation results from breathing dust con- iiairniig free silica mixed with other minerals. Although a great deal is not known' it'mixed dust reactions, there have been sufficient examinations of the lungs of