Document pBLQNVGYa7aJRKq3p5BjngOKk

R&S 109724 '***,'** Bl'O-MEEflCAL RESEARCH DOCUHZNT DESCRIPTION PORK 63 68 69 76 Duplicate In all cards:--> /f ons4ffi>T~ year as-1961- File lumber [Right justify [Numeric only] Author (s), as Last Name FS (No Punctuation) and coden for journal as JAKA preceeded-by. one blank space 1 ' 20 -21 40 41 77 78 Sub-Index Code 61 62 11 12 13 __ Title of Report: end with space-hyphen-hyphen-space. Follow with Index Terns. separated from each other with -comma-space. Avoid other punctuation; do 'not abbreviate. 12 * ' .* . *.* 61 62 21 ^4/, / LOV'1 / ok_ / . '--/i r/ , -'- -- ' ' 22 (/ y 23 24 Source (Journal, Vol., Number, Pages, Date) 12 u. ....................................................... ;' ' ' n '1 <u- f ft A > r- /97'= . ?>'- C, !&* 7J-~7- Vj V v~ 61 62. 31 32 Brief Summary' 61 62 61 62 63 64 -L I* oq rs V r\ V/ <O?03 Figure 7. Left. Irregular fibrosis of portal tracts and focal nodular fibrosis of the hepatic capsule. (Hematoxylin and eosin; original magnifi cation, x 45.) NIH accession number S74-411. Right Portal tract from the same liver shown in Figure 1. The fibrosis Interrupts the limiting plate and extends into surrounding hepatic parenchyma. There is a slight infiltrate of lymphocytes and minimal proliferation of bile ducts. (Hematoxylin end eosin; original magnification, x 160). NIH accession number S74~411. (Reproduced by permission. Ann NY Acad Set 246; 174-194, 1975.) -cact with other intracellular macromoiecules (DNA, WA, protein, lipids). Although Gillette and others have ct yet attempted to correlate the covalent binding of .active metabolites to DNA with carcinogenesis, such a action has been speculated as a potential mechanism for .rcinogenesis. Recent work in our laboratory and elsewhere, much of still unpublished, has included studies in rats on the c of ingested "C-vinyl chloride monomer, and the isolan and identification of the major urinary metabolites this chemical. The ingestion study showed that' vinyl 'oride monomer is metabolized to polar products that ^ readily excreted in the urine. These results also suprt the hypothesis of dose-dependent metabolism. The atic nonprotein sulfhydryl content of rats exposed to ! I chloride monomer showed a progressive depression ted to the concentration and duration of exposure, iiistent with the sulfhydryl depression, two of the three ' try metabolites isolated thus far have been identified hiodiglycolic acid and N-acetyI-5 (2-hydroxyethyI) erne. Thus it seems that vinyl chloride monomer or -active metabolites covalently bind with hepatic gluta- and are subsequently hydrolyzed and excreted in ; ;ne as conjugates of cysteine. her studies on vinyl chloride monomer continue to `ft the hypothesis that its carcinogenicity is related metabolic formation of reactive metabolites. Studies -; have shown an enhanced positive mutagenic re' in certain strains of Salmonella typhimurium ex- Jo vinyl chloride monomer if microsomal enzymes iificd liver homogenates are present. The metabolites monomer identified in the urine of rats exposed to mical indicate that the primary deactivating mech anism is by conjugation with the hepatic nonprotein sulf hydryl compounds, glutathione and cysteine. Our current research is directed toward further elucidating the metab olism of vinyl chloride monomer to reactive products and their potential to bind with intracellular macromoiecules. Resolution of the metabolism and pharmacokinetics of vinyl chloride monomer will undoubtedly be of great help in resolving its hazards and will ultimately provide a scientific basis for guidelines concerning tolerable levels of exposure. Histologic Features: Hepatic Fibrosis Dr. Hans Popper*: Only little more than half a year ago, I became acutely aware of an effect of vinyl chloride exposure on the liver when, within 1 week, three persons called this connection to my attention. Doctor Lelbach from Bonn, Germany, sent a reprint about a peculiar intra lobular fibrosis of the liver seen by peritoneoscopy and liver biopsy in workers exposed to gaseous vinyl chloride (7); Dr. Selikoff called me and asked what I knew about hepatic angiosarcoma, a rare tumor newly observed in the same type of workers in this country; and Dr. Thomas, here in Bethesda, showed me histologic slides from several such workers. Subsequently, I have had the privilege of studying, with Dr. Thomas, a large amount of histologic material that has been collected in the Laboratory of Pathology of the National Cancer Institute. The following report is based on this cooperation, and, I hope, shows the heuristic value of environmental pathology (40) in rapidly assembling information that might enlighten other areas of pathology and medicine. * Gustave L. Levy Distinguished Service Professor, Mount Sinai School of Medicine, New York, New York. Berk et ml. Vinyl Chloride and Uver Disease 727 R&S 109726 Fleurs 8. Irregular, focal dilatation of hepatic sinusoid*. The size and number of the sinusoidal lining celts are increased. The hepatocytes also vary In size and focally appear to be proliferating. (Hematoxylin and eosin; original magnification, x 400.) NIH acces sion number S74-415. In reviewing the serious hepatic lesions encountered in vinyl chloride polymerization workers, we saw that two distinctive lesions were prominent. One, angiosarcoma of the liver, has been the focus of most of the attention in this study, and its histologic features will be presented by Dr. Thomas. The second is characterized by a peculiar form of hepatic fibrosis, which, in many instances, was initially diagnosed as cirrhosis. In some of these workers, the lesion was associated with portal hypertension and variceal hemorrhage, leading to the performance of a portacaval shunt, during which time a wedge biopsy of the liver was obtained. In other cases, the lesion was diag nosed on the basis of a needle aspiration biopsy. It is of considerable interest that, in vinyl chloride workers in West Germany, severe portal fibrosis with significant portal ' hypertension, splenomegaly, and thombocytopenia--pre sumably on a splenomegalic basis^-is relatively common while angiosarcoma is rare, whereas the relative incidence of these two lesions in American workers seems to be reversed. The typical lesion of vinyl chloride-associated hepatic fibrosis consists of three features (Figure 7). The first is a typical but condiagnostic portal fibrosis, varying in degree throughout the liver. In places, it seems aggressive, in that fibrous tissue extending into the lobular parenchyma distorts the limiting plate. It also extends into the walls of the portal vein branches, separating their muscular fibers. Sometimes accumulation of dense connective tissue is as sociated with proliferation of bile ductules and periductular inflammation. Inflammatory cells also aggregate around some bile ducts, and this pericholangitis might explain the focal canalicular cholestasis seen in some specimens. The second is capsular and subcapsular fibrosis, in a nodular form; it is the most characteristic lesion, partic ularly visible if the surface of the liver is inspected on peritoneoscopy, as reported from Bonn (7, 20). Distinc tion from cirrhosis by gross inspection is difficult. The third type of fibrosis is subtle and reflected in a focal intralobular accumulation of connective tissue fibers, rec ognized distinctly by light microscopy only in connective tissue stains. Electron microscopy (17), by contrast, de tects a dense but thin connective tissue coat surrounding the hepatocytes and associated with many fibroblasts and fat-containing mesenchymal cells--Ito cells (41) or lipo cytes (42)--which have been postulated to be precursors of fibroblasts (43). This fibrosis differs morphologically from that seen both in chronic active hepatitis and in alco holic liver disease and suggests a different mechanism of development. Where the intralobular fibrosis is conspicu ous, it is associated with bulging sinusoidal lining cells with a prominent diastase-resistant, periodic-acid Schiff reaction of the cytoplasm, which b sometimes granular, as in phagocytosing macrophages, but more typically dif fuse. The hepatocytes show no significant changes except that, in the areas of prominent sinusoidal lining cells, they show variation in size of both cytoplasm and nuclei in that large hepatocytes, sometimes even multinuclear, alternate with small cells (Figure 8). In some instances, particularly in autopsy specimens, regenerative nodules are seen with out cirrhosis. Besides this pattern of fibrosb seen in all specimens, some specimens--both from patients apparently free of angiosarcoma and in two in whom angiosarcoma was later found--a focal irregular sinusoidal dilatation was noted (Figure 8). It did not seem to be' related to passive con gestion, since it was not predominantly in the centrolobular area. The same type of focal sinusoidal dilatation, pro gressing almost to peliosb, has been observed in patients after treatment with anabolic steroids (44) and contracep tive pills (45). However, in these latter instances, there have not been any reports of progression to angiosarcoma. In our vinyl chloride cases, the sinusoidal dilatation is associated with proliferation of the sinusoidal lining cells, which become enlarged and show bizarre nuclei and, as will be discussed below, progress to angiosarcoma. Thus, we can conclude that this sinusoidal dilatation is a pre cursor to the tumor in vinyl chloride exposure, but we have not yet clearly identified the nature of the cell under going malignant transformation. In cases where we were able to study the spleen, we found it distinctly enlarged, and, particularly on laparos copy, it showed a nodular but irregular, type of capsular fibrosb (7). On the cut surface, the follicles were con spicuously enlarged, in contrast to cirrhotic fibrocongestive splenomegaly. Hbtologically, fresh hemorrhage was seen in most spleens, although some showed calcification and iron incrustation in the form of Gamna-Gandi bodies. The cords of the pulp contained many erythrocytes, characteristic of hemolysis. The lining cells of the sinuses were activated but, for the most part, not fibrotic. Study of the pathogenesis of vinyl chloride-associated liver injury (46) showed that vinyl chloride or its metabo lites seem to induce a hyperplasia of two types of cells: the mesenchymal sinusoidal lining cells in liver and spleen, and the hepatocytes. In the spleen, activation of the sinusoidal celb may result in splenomegaly, and, in the liver, in fibrosis contributing both to portal hypertension and the formation 728 June 1976 Annals of Internal Madicine Volu/na 84 Number 6 Figure 9. Lett. Sinusoidal pattern of angiosarcoma. Sinusoidal spaces are large and Irregular. Angiosarcoma cells line these spaces and ensheath hepatic cord cells and an increased number of non-neoplastic-appearlng ceils In the space of Disse. Bile plugs are present in bile canaliculi. (Hematoxylin and eosin; original magnification, x 392.) NIH accession number A74-31. (Reproduced by permission. Ann NY Acad Scf 246:263-277, 1975.) Right. Another area of the same angiosarcoma shown In Figure 4. Spurlike projections of hepatic tissue project into larger, more cavernous cystic spaces. The hepatic cords are disrupted by degeneration of hepatocytes. The tissue space of Disse contains in creased collagen and reticulln fibers. (Hematoxylin and eosin; magnification, x 100.) NIH accession number A74-31. of septa. These septa may progress to cirrhosis. Although we have not as yet noted this progression, it has been ob served by others. Sinusoidal dilatation develops, and in this setting angiosarcoma ensues. The role of the activation of the hepatocytes, which seemingly form a scaffold, is problematic. However, it is worth noting that we have anecdotal evidence of primary hepatocellular carcinoma in persons exposed to vinyl chloride. While studying these cases, we became aware that pro longed exposure to trivalent inorganic arsenicals, such as Fowler's solution used to treat psoriasis, results in the same clinical and histologic picture (47-49). Histologic examination of two cases made available to us by Dr. Peter Scheuer showed the same histologic changes as in vinyl chloride-induced fibrosis. Moreover, exposure to such arsenicals has also been associated with hepatic angiosar coma (25). In vineyard workers, in addition, it has been associated with primary hepatic carcinoma and cirrhosis (24). The mechanism of toxicity of arsenic has been re ported to occur through its reaction with 6,8-dithiooctanoic acid (a-lipoic acid), with the arsenic forming a stable bridge between the two sulfhydryl groups (32). Certain hypothetical metabolites of vinyl chloride formed by. the mixed function oxidases would also be expected to react in a similar fashion with a-lipoic acid; possibly explaining the similar pattern of both fibrosis and neoplasia seen with these two superficially unrelated chemicals. Interestingly, thorium dioxide (thorotrast) also produces the same spec trum of lesions (22). The pathogenesis of the noncirrhotic portal hypertension in all these instances may be related to a discrepancy be tween increased splenic blood flow, induced by the hyper plastic splenomegaly, and to the impairment of the distensibility of the hepatic vascular bed produced by the various forms of fibrosis, which by themselves are not :onspicuous (50). The fact that this type of portal hyperansion has been produced by chemicals, at least some of them environmental, suggests that idiopathic portal hyper tension, found only sporadically in the Western world but more often in some areas of Asia and Africa, might result also from toxic, possibly environmental, chemicals. Histologic Features: Angiosarcoma Dr. Louis B. Thomas*: We have reviewed the available pathologic material for a group of vinyl chloride workers who had a peculiar hepatic fibrosis and focal sinusoidal dilatation associated with proliferation of sinusoidal lining cells. In addition, we have studied the hepatic lesions of 15 vinyl chloride workers who developed angiosarcoma of the liver. The hepatic changes described by Dr. Popper were also seen in the nonangiosarcomatous areas of the liver in all cases in. which suitable sections were available for review. From these, observations, we concluded that a continuous spectrum ,of changes occurs, starting with multifocal areas of stimulated sinusoidal cells, followed by increasing degrees of atypia and proliferation of these cells, and culminating in progressively growing, multi centric, infiltrative angiosarcomas (51). Of those patients with angiosarcoma who died and were autopsied, postmortem examination of the livers showed massive involvement by cystic, blood-filled tumors that replaced most of the tissue. The liver weights ranged from 1860 g to 7300 g. The average weight was 4236 g. In the larger specimens some of the cystic spaces were several centimeters in diameter and were associated with large areas of hemorrhage and necrosis. Rupture of these large cavernous cysts followed by intraperitoneal hemorrhage occurred both spontaneously and at the time of surgery, and it was the immediate anatomical cause of death in several patients. The liver tissue was also irregularly re placed by small cysts that varied in size from 1 mm to 1 cm in diameter. Most of them were filled with blood; only Chief, Laboratory of Pathology, National Cancer Institute. R&S 109727 Bark at el. Vinyl Chloride and liver Disease 729