Document nmzpgjgRo5bYGo9XpL3zrJXNR

STOOI 1692 TS06J i i envu-.on.mii-nt.u. Rusrancu 2, 30-16 (19GS) Pleural Fibrocalciflc Plaques and Asbesfos Exposure Limi 0. Meurmax Department o] /'ufWopp, Cent.at Hospital ol Kuopio, Kuopio S, Finloi\d Received December IS, JSG7 la i number ot serial investigationa a irsociatioa h been demonstrated between the development of benign calcific pleural plaques or miliguant difTu.ro mcsotlidioina and alight inhalation of asbestos dust, often some 20 or 30 years previously. .As the industrial use of asbestos baa increased enormously during the last fc\r decades, a rise in the frequency of mesothelioma--which has hitherto been rare--is anticipated in the near future (Thomson, 1902). From the standpoint of epidemiological research con cerning asbestos exposure, the demonstration of calcific plaques on roentgenograms has proved a useful eriteriou. So far, only -en association has been disclosed, however, not an obvious causal relationship. Other pathogenetic factors, still uukuown, leave to be taken into account either as a contributory or the sole cause. The occurrence of bilateral calcific plaques docs not yet imply the presence of asbestosis-pacumoconiojis. In the majority of subjects who have not been occupationally exposed to as bestos, pleural calcification is not combined with pulmonary changes or signs of pneumoconiosis. Occupational Exposure to Asbestos and Pleural Plaques In rocntgenographically visible form, pleural calcification is relatively rare. The most common causes are hemothorax, pleurisy (usually tuberculous) and chronic euipyciua. In extensive roentgenological series the frequency of pleural calcification has been reported to be about 0.2% (Floyd and Ilepbum, 1939). It has been estimated that the lesions are bilateral in every fifth or eighth case (Claus, 1962). Bilateral pleural calcification attracted more gcueral intcresl when Sicgal e al., in 19-13, reported that they had observed this condition in 6.3% of talc miners in the northern areas of New York State (St-. Lawrence County). The theory of a causal relationship with talc in this region, in the form of a fibrous, asbestiforin mineral, trcmolitc, was advanced. It was not until 12 years later, however, that bilateral pleural calcification was again described, this time by Jacob and Bohlig (1.955) in-5% of.asbestos workers in Dresden. Independently of these authors, the Danes, Frost el al., in 1956 directed attention to the associavun u,' ii.'uL'tvj cxpuiiuc ana ptutrai calcification, in a senes ot' 31 insulation workers they detected 11 cases of pleural calcification, S of which were bilateral. In the insulation materials used, asbestos constituted an essential element. In many later investigations an association between pleural calcification and ex posure to a-diestos has been demonstrated. The tno-t impoit.ml statistic.' on pleural plaques and a-hestns exposure are listed in Table 1. It has |,rcn found that the more severe the degree of pimumO'CtiiO'i- oh-erved among a-he.-los v,others, the higher is the ftei|itv;try oi ph ur.;l caieifu aliuu. 30 STOO11692 STOOI1693 ASRK'.TOS AM* t'MAIUI. JU^pTH 31 Mil Hit II0G2) J, (,-rUd pleural cnlrifir.il ion in 0% of a giuup workus who showed lli slightot n* nlgMtngi.aphic degree of :i.- Ik-dosi.-, I*iIt,* the con i>| Kind ing ftgurv was 3S^f in .1 group win* had pulmonary change:; of llie severest degree. Among 1117 members of tlic lltat and Frost Insulator* ami Asbestos Workers Union in Xew York, SclikofT (19G5) found 130 ruses of pleural calcification. Of these, Mo were in a group of 303 wotkers with a history of more than 20 years* exposure to Asbestos. Among those who had been a shorter time on the job, only 5 exhibited pleural ratification. SclikofT observed, moreover, (hat calcification rarely occurred witJKXit fibrosis of the lung parenchyma--nsbestosis--being pres* ent as well. The majority of investigators hold the view that rocntgcnogrnphically dis cernible pleural calcification is a sign of nsbestosis (1) if tlic lesion is bilntcral, and (2) if there is no previous history of hemothorax, tuberculous or other pleurisy, or empyema (Frost cf of., 19o6; Ifurwits, 1061; Anspach, 19G2; Lawson, 1003; Oo.stliuixcn el al., J0G-I). Under the last-mentioned conditions SclikofT (1905) regards unilateral calci fication, as well, as strongly suggestive. The association with asbestos is brought out by the fact that not even in large groups of workers in gold, coal, copper, iron, chrome, and manganese mines was any typical case of pleural calcification discovered by Hurwitz (19GI), who investigated the chest roentgenograms of workers at difTercnl mines in South Africa. Those subjects showing calcification were invariably asbestos workers. Glnsswool and nxkwool, which are commonly used a* insulation material in tho building industry in addition to n.djcdos, also occur in disintegrated form as fibrous dust. However, such data as are available suggest that they do not seem to cause pleural calcification even after protracted exposure (Djuic ct al., 1004). On tlic other band, it is noteworthy that nshedosis and pleural calcification by no means invariably occur in conjunction. Of 30 patients with jilcurnl calcifica tion described by Ifouvihanc ct al. (I9GG) from the London Hospital, only 7exhibited nsbestosis-pulmonary fibinds. Further, these authors found .only 8 cases of pleural calcification among 30 patients with asbestosis. Cartier (IDG3), also, mentions thnl the majority of Canadian industrial ndxvdoi workers with pleural rnfrlnosls showed no sign* of a>l.etod, and that in most eases of ns bestosis, pleural calcification was not detected. Moreover, Cartier drew attention to the fact that of 120 Canadian n.dre.dos workers exhibiting pleural calcifica tion, 00% had worked al one or the other of four smaller mines, while only 10% 'rmu- fm:n a larger mine with !f.00 umber*, and no ca-e of calcification ua> ob served among 1S00 workers employed at the biggest mine. From this Cartier concluded (lint tbc factor rau.-ing nsbedodi is not the same ns the factor that leads to pleura! calcification. IVhre (Muller, 1058), loo, slated Mint irgional factors or contributory factor.* relating to the paitirntar indtidry may *L of importance to the development of pinna,J rnh-ifiralion, dure ,01110 investigators see these lesions in nhumlaiire white others observe none. Ife suggr-ti-if t|,..,t different c ompo-it icm of the du,t involve! i,,i,;ht afford an espla iml'inn to the irregular occurrence of cnleifimlin,,. Nev.i thc|,-,.c, j. may |l0 regarded a* cs- ST0011693 'J.6.9.1 100 IS ST0011694 III o -r 3 * 3 X 3 J? + <r + I + + 1 <1 a S 3 s jj 3 2 5 3 3 3 3 2H 3 /: 2 -f a 2q 3s 3s ,,J 1 "5 a < 1 J , 4 * I 1 3 f 1 3 i1? -il d .= c3 23 JJ v 3 u L> u* A in j d = i*. d ill s f 11 s- f 1 -f 111 s It s | jl rl fI < - d HA ..tc 3 * -i -i d rrrr^r.rs '*'* vt tn cn <z: O' u: cr ST0011695 34 IAURI O. MKUKMAN t*blilK-d that nil tyi> of n.-lotos may lc associated with pleura I calcification ! /inn it Ims boon drlrctid in l>olh Jcrjcntic and amphibolc nslrcatos workers and ^ in worker* exited to trcmolitc tale dud. Cnlcificntion linn been described in --i workers from the Candian chrysolilc asbestos mines (Cartier, I9Go), in worker* O from tlie South African crocidolito mine* (Sfegg* lCO# d in subject* rs|KMcd to dust from the Finnish anthophyllitc asbesto* mine* (Kiviluoto, 1900). -- In this connection it seems appropriate to emphasise the fact that except, cn perhaps, under laboratory conditions, asbesto* duct cx|w*urc is never "jiurc." The "3P dust is always mixed in various degrees with other dusts, as other mineral dusts. f; At pment, we do not know whether and to what extent tliesc other mineral* cause . a pleural ealcifieation. Hut it should be recalled Hint pleural calcification rr*e first "f? described in tale workers who had been exposed to duct composed of tretnoBte- talc, asbestos, and anthophyllitc. Furthermore, in tlie studies performed by Smith (1952), calcified pleural plaques wore found not only in trcmolite worker* but also in certain groujis who had handled various other talc mixture*. -- Ncmocatpalionnl I'lcurcl Catdftrnlinn 7 ' .'-jt; Jrrthe population living in the limited area comprising the Finnish anthophyl- Jite asbestos dcjwsit*, topical bilateral plcurnl cnlcificntion is common without - occupational exj>oiurv to the dust having occurred (Kiviluoto, TWO). In a commune (Tuu-uiemi) in which an aslicstos mine and mil! hove bee worked since 1019, calcifications were delected at roentgenological maar HHvey* in 0% of the adult imputation. In tlie nrighlioring commune (Kuusjarvi) the COT* responding figure was G.f>9r. In the remainder of the Finnish population ptrara! calcifientions are a rare roontgcnogrnphic finding, the frequency being estimated at only O.Ji |x.r thou>nnd of |>opulntioii (Ihuiuio, I9G0). "~t' Kiviluoto discovert d I2G cases of pleural cnlcificntion in a series fiMfetbe- x 01 u|wuil', iiu'wut, m-T-ti not necessarily dc precisely me tisuostos muM^ u*ew tain observations seem to indicate that scattered asbesto* rocks and aEWifroeeurring in great numbers in this area may be a source of asbestos 1 T.nvn fact (hat the.e mromhii'fibte t|ni>r* have Iw-en u>rd hv the loesl lopuiation mi Hie cnmum-noii 01 iircpi.-icea nnci Hove*, uuu c*|>cetany lor tnc heated stone* in the Fiimi*li hath ("ruimn*) on which water U throws jfrbrdtt to produce -team. It i* nl.-o known that the children like plavimr wfAsoch indicutf* dial (In- a -11< -In- rv|h..i(ic of ||luie> onlliiflicrr aag<' rump-. in any cwnt/WWT*t have U (-iiii h. foie (In- r\|>1<<ir.11 i,>,, nf tini-- ::ii^^ttKK\\~*mm.. j.<> i(- ua- htariiaf. Similar riofi uuV pf.-m:if e.i feifie.it inn hian---- rrececii-nntt ty b-en di-seribil in lodged*, STOO11696 STOOI1697 A>lii:>ro.-i ANU I'l.KI N\l. I'l.Mp I n.i nlicrp a high frequency of ph-urnl rnlrifieatiun was nodd in tin.' p"pnl.,lii :i (con sisting mainly of fanners) living m!k)hI ;i -mall a-ts -(u- mine. In tlii- e.i-o, loo, it was suggested I ho :i.-ltv.-ln content of (lie .-oil wa- a :h<mc lik< ly -nnrcc of exposure limn 'tmosphiTic pollution derived from the mine (Znluv <f at., 1907). .Endemic pleural calcification in nil urban population re-Hing near ;m n-liceto* factory is descrilicd in Anspacbs (19G2) roentgenological study in the city of Dresden. Among 2M subjects wicli pleural calcification 177 li.ui a hU'my of ex posure to nshestos dust due either to working at the a-he;to.- factory or to living within a radius of 1S00 m from the fm-tory. Endemic pfcurnl calcification without known c.\|)0'tire to asbestos dust hat also been described. In two arms in Czechoslovakia, i.c., in the district of l\acov (western section of the former Jihtava region) (Ifromek, 19G2) and in the district of Pclhrimov in south Roheniia (.Marsova, 19GI>, bilateral |d;iquc-like pleural calcifications were found in relative abundance during roentgenological mass surveys of the niral jwpulation. Neither fibro-is nor any other di.-ene of the lung wu observed in tlcso rases. Hromek was unable to trace any asbestos exposure, ami Marsovn succeeded in suggesting only tmrritam exposure to tremolilc talc: The soil of the district of Pelbriiuov being j>oor in calcium, farmers import, from the ncigh)>oring district of Cliynov, a fertilizer called ` Kalcofen," w which contains small amounts of (romolilo talc. Mar.-ova later studied the occur rence of calcification in the district of Cliynov; the ftcrjuint-y was only 0.3%, while it was ns high n* 1.3% in certain areas of the district of JYlhrimov, At roentgenological mass surveys in the area of Leipzig, Nref (IC93) detected 33 typical cases of bilateral plnrjiic-like pleural calcification. The nliofe serin comprised 1!!,0G9 subjects. Caleificil pleural plaques were more frequent in uomen than in men, a phenomenon which also was noted hv Mar.-ova in Czechoslovakia. No changes justifying a diagnosis of pncunioconinsi-- were observed in Ncefs eases, cither, and only four subjects had n history of occupational cxj>qmi''C to Asbestos or talc. Neef regarded bilatrrnl pleural calcinosis n merely a change of old age. It may thu< !>c considered established that although pleural calcification is fre quently seen in workers cxpo-cd to nslicstifnrm dust the majority do i;nt -hove this condition (Mllller, 1002; Curlier, IDOo; lrouriliniie, 1000). Furthermore, it may be ftnled that (he longer the time tout hag elapsed since the beginning of oc cupational dust exjioMirr, the higher is the frequency of pleural calrifieation (SelikolT, 190.3). However, plnque-likc lulntcnd jdeural calcification cannot be regarded as identical with a-lscstojis, since in unsrJeefed material from rocutogrn- '11'i* 11 11*- *' r\ > e- tl:i* *-" ... .-.-.I t...,.,, tv I mad' r. t oid v dii* jdmra. In the majority of cases (lie change* are not ur*orialii( uni, .i,mui..-n.,:,tl- umi.-m of the lung, nor do they cause any subjective or objective symptom- nr signs of nsbestosis (Kiviluoto, 19U0; Rauuio, 1900). In some sctics of n.n'o.nipition.al, endemic plaque-like plmr.., ralrifiralion, exposure to a-bc-fns has In n uiimr- tain (Mar-ova, 1901), or ovid absent (Hromek, 19021. On the *>iti< r hand, it should be pointed out that (he role po-sifdy played by a-he-to- r ii.i.ut lx- de- fioilcly f limnmted long a- (hr luii;;< hal e tint hen, | '*<.,f,.j,.|j%x for n.-!>r-N> filters or IFin- ,,.,j Comparative autop.-v studies on the relative fn-r,,j, ury of pNin.il n,,,( ST0011697 8691 I001S 3G Mi hi n. Ml I l.'Ml't J T . llip rontclll of II'I .. l*l - l [l l-1 f .1 - I if* I 11- 11* idle. I ill t lie hi llg- ha VC t.f i II | m l fill Mil -if only III linglatid (Mniuihaiie ft III-, I'JGI'.I :i 11< { in Finland (Miuiinun, IflGG). Ill an nutop-v >. ii- fuu> tf I.ond.iii I lo-pilal, I>f-if(II*--fif.I- |d< urnl thichi nin;'.- Wide olr-l-l \ ill ill 12 I I 2'i . Ill rill ihc-e ra-e- M n:i II n m >n r: t - of n^ln -(n- In.die- wcic recovered from llie Inn;'. ,M rnn-i entire autop-ir. p< rfui nn d in llir .-nine Fio-|iif n.f asKstos liodio lu-if detcitcd in 24.3%. 'J'hc Finnish investigation wa- performed on a (<dnl of 4.1? couscculivc autopsy cae> at three central ho-pitnls .-itunlid far from cadi nllicr in dilTennt parts of tlic country (Mem man, Klfiii}. (in- central hospital district include? antho- phyllitr BiiiriliH depo-its. The freijiicncy of pleural plaques was 30.3% in the whole material, the range K in;; fiom 13 to .'>7%. The lungs were cNamincd for aslrcsdo* 'oorlies at tho-e two Im-pitals where plaques were most fri'queutly wen. 'this series comprised 219 ea-c*. Pleural plaques were observed in 12-1. In 70% of lhc>e, arlicstos lodii- were found in the limps in varying, mostly small amount*. Acconlinjfy, ashe.-tu- v.a- not demonstratisl in the lungs in all cases showing ? plaqww, rwhon the other ItanJ,. hut b^'ifttriiiTjhjhl/ foim'! in the'caws , _ exhibiting **he*ton l>odie*. In tKe-whote material asbestos Ixxlios were observed ' in 67.t55Ki?- The corks* from I.ondnn and I'inland tlm- differ in certain ir-pect-. In tl.c --`Fhttiwh study the fri-cjiiti*i-y hath of ca-c' showing phiepics and cn`i" with n-- bc*tCH in the lung- wa- Iii;;fi( r. Moreover, in a o|>oilion of the c.vrs with plaque.- (21% ), n-h- -to- wa- not ileinon-tiatein the lungs, while in the I.nnd'.'D series a*!>c1o- w a- found in tin- lung- in all ea-i- show ing plaques. In rcsfiert to anatomic .tructure, the plaque* were identical in the two series. They nl.-o u-ually .-howi d c.ilcifi' iuinn varying in degree in both. In the majority of ca?c- calcification w.i- nut heavy enough. however, to make the plaques viritdc on nuitim- che-t roentg. 1.071 .im-. Another not* woitliv dih; leuce hriuien the Finnish series and tint from Ixnidon i* that in the la tier nlinn-t half llie case* with plnqueJ showed clinical, or in any event hi-tolngically d.-mon-irahle, n*Ix*stosi. fpulmonmy fibrosis). In the Finnish 'eric" (denial plaque* were not a--ociatfd wit!) fihro-d.- or anv otlicr chronic di-m-e of the lung C'nti-qitently. although in tlir Kinni-h -nic* ca-e- showing loth pleiir.il pi iqui - and a-la-tn- bodies wen- highly signifirantlv more frequent than ca-e- in which (hi- n hitimi-hip wa* not observed, the roiirhidnn cannot, lie diawo tied an on. mplic.iled causal n latiou.-lilp is involved. Thv possibility remains that j.hural plaque* are due n!*o to other, unknown fartor*. The same i? sugge-hd f.y sfati-tii -- derived from atito|xy material from tle two largo! hospital- in Mi!.= n A-h<-tn- Imdi. - wire found in .**)% of ra-e-, p|,,u;!! t " i............. Thr l\t>* /. tj* u<>'V njJ f . 1 /;" -11 <i >'r't ft i f*h i'r l f C'lIdfriit I It 1 r*-ld |>. >'.-l a ' . (! >C 1 i :!. if e.ir im.. .'.p|-ai a- pateln- and n .-til . d.- O! pi:..pa - fe-:. . > * . I 11 f \ (if t li(J. r. n' |i.ittein-. v.!.i.-11 I. 1 \ t* 1 n ; i <h>ri it.. .1 a- bi/ .i.. i , ! , ' -' h'.. . o: la re- like I I'l; . I i. If! . i ( 111 .1 (:.d ii.; . ir, V .1. . ..; * i . , .1. ; r,.... itfi r i* *.r*. r*.i,i j11mri\ -v;..'. * 1 it* ((I'M "i\ . ! . 1 - ii i . \ r. .!* f !* llll* !< Ill MI'I II. *ir fr7*' : ST0011698 b A-nr-m- \\ii I'l.n ti .1. pi.\gm 37 STOOI I 699 r / / .> t i KlC. I. Rori.l '^rnn^r i mi ttf .1 TO-' .r-oM f n m r .-Imuiinc Oil tit 1 il rtltifit' j-Imii.O Ifr hml never lrcn nn i.tv.i.. \t.,il.ti', Inn Itr In.I .,!! lit* life Ii\sl in a re^t, n t .ttilftttin^ aJ>rato ft I a tl|.liner nf t Vm ft.mi one .vtiro lot mine in*l 12 km fre>m ftiwiilwr, otluT calcifir plrnrnl rl lances (l/niuitz, lOfit; R.iunio, I9GG). nilatrr.il, sym metric involvement is wry , Im net, ri.-tic I Kivilur.lo, I9G0; .\la.Mi\n, 1001; Peliknfl, I9(>n; Kannin, IRO.fti. Tlv left side is more heavily n fleet n I, and in unilateral case? il is tlie >iK- more nfim involvetl (Kivilnoto, 1000; S'likofl, 19G5; R :.iiii:o, 1000). I In* l.tfei.tl pri'limis of 11 tt- iiieMlo and lower field- . i n 1 the central j<ortion of th 1 i:i[> 1 iu^in arr tiic .mm nf predilection, Iml in more ndvnnrcd eases rah-ifr me are n'found on the jilenr.il snrfiCk. of tl peri- -----1......... P *s I..............I.I..I .' I <1-,. . :............ t ,x,, .. f, r,,n,t streak.' tin- ihiiitioii n| the i j 11> in th,. Iatei.il j i >t I :< n i' n| lla , in-t (Kivihmlo, 19001. Cnleifie ph.f|tie- are mn-tly fxitiel on th"1 jinru l:tl pliti.n, n hi- nl-n ls-en cstatili'hi il .Miatninie !Iy iSinilh, I9.'.2; Trine, Itl-Vt',; Ki\i!u..fr>, I9T.O. W mkh-r, 19(> I ; ^f a i ova, 190 11. I In- j f,ii i a I i\i \ ity j- n -nal'y nn fn in :m\ i v < 111 in ihr area nf pla<|H< fmmatam f Teh 19.V.; Miiltri, p.t.Vt; K;'i. .an, 1900, \ fn, 190.0). STOO11699 STOOI1700 UUU&JOXBUX ST0011700 STOO I 1701 A>uvnrwn ,\xn rr.M'Ktf. ri.HH?*:* 30 Piilhritoglcnl Anatomy of rtt tu.it ('tilo'ficuHon* Greedy, the calcific plaques mvii in the parietal pleura, and sometime* in the visceral pleura well, nro |mlrtlii-likc thlvkcuing* with n shiny turfncc. Tlv.7 re pearly white or ivory in color and often project more or Urn abruptly, like n plateau, ovrr the surrounding tisMic (Fig*. 2 ami 3). Tlicir surface may be eilltor smooth or nodular, ns if jarkcd with split |h:. Tlic plaques show wide variation* in thickness, the range being from nlwrt 0.3 mm to 10 nun 01 larger. The variation m extent i* also ctmcidomble, from small sjKrk* about 0.3 nn in diameter to nlmoki continnona plaque* covering the parietal mid visceral pleurae. It i* noteworthy, however, that the plaque* feem to "avoid" the corner* of llic chest, finer lesion* arc not found in the phrenicocostal sinus or iu the nren op posite the npiec* of the lung* (Mcunnnn, 19G6). Histologically, it has liven established that the calcified plaques consist of collagenous, hyaline, sclerotic connective tissue poor in crllr, in wliich calcium has secondarily acnmiulalvd in varying amount* (Figs. 4 mid 5) (Smith, 1032; Fehre, 1930; MfilJcr, I03S; Meurmnn, 1900). The calcium concentration *how wide variation m different plaques in tlie 1.1111c rase and also iu different part* of the fame lesion. The calcium content, but not tin; thickness of the plaques, is decisive for their visibility on routine roentgenograms. A heavily calcified plaque apjienr* yellowish gray and transparent, and if it is peeled off from the inner surface of the thorax, which is readily done, it feels lime-hard and fractures when bent. Plaques with a lower calcium content feel like cartilage and bend like leather. Patho-nnatomically the plaques correspond to the changes that have long been known by jmthologists under the name of "sugnr icing" or "frosting" (German: Zuckorguss) (Mcunnnn, I960). These lcfinns, the etiology of which has remained obscure, have mostly l>ccn encountered on the peritoneal surface of the liver and spleen, fail also on the pleura nnd pericardium, ami occasionally on the intestinal scroa (Ilorrmann, 1927). Pleural plaques of the type described alxjve, as wrll as "sugar icing," seem to develop n* primarily chronic lcions, i.c., without any inflammatory, acute fibrinous stage followed by n grnuulatiun-tlssuc ctage (Mcunnnn, 1000). In no case of plaque* so far inve-tigated has an acute primary stage !>een observed. Also the thinnest plaque* have been bumd to consist of collngrnou* hyaline sclerotic connective tissue. The accumulation of ealcimn in the plaques is obviously ft late, secondary ' 1* i'll n a llv 11 K>!i^( r.il >!c calcific plaques have so far not liccn found in subjects younger (ban .10 yearn (Kiviluoto, 1900), while well-developed, weakly calcified pleural plaques have bevn observed at autop-y in an 18-year-old subject (Mi-urmnn, 1900). It is a well-known fact hn. 3. Tlir:icie cavilv of nil 3|.\rnr-nM np idillurnl wi.rUr wllo ,|ir,| ,,f liri.nl[. com* ti,e to 1,,-rr "rho-i* There are lypi.nl. fl.irk l.itilcnl *j,h v,w catcimn coo- ^"lr,r|..n, ,,,,i vl.ilite on mriiiurnnirr.ini*. TU m.I.Jci 1,,,| Ii4r,| ,, ,||.lr,n^ ,lf n,mll I n" 1 , f'"y ",,nr' of ItIC nrra onl.lining n.J*-to* rhpo-il*. He T. ..I not I.nn.llc.l s.U... nr,,,,Mii..:.Uy. No n-U.ln. l.-lin. rr- rmnrml Tr..,,, a fun* nr. In.t ill llii.'k ini'S i lm,i. I w 11 t |.ir:i! vl- -In. Inali, ff *, rr fimn>|. ST0011701 ST00 I I 702 40 mviti o. mcukman _ I wfc. ----. .. -- . . k^T. i* ^ %/im ^ > i 4 I i* ' k# ' *. FlO. f. F)inrni<rn-/r.-t;'>( of .1 hutolV'^t o*"fJoi from the ISAr^ta of t, pUf|ii** rlto>iiis tr.io-iii<'. tVi.fn ooJin.uy .vy v(tie'TKiti< rorin*-r(irr ti--<n- (* r rW-rutir. f*ci-l>ot- .n r. |;f. ti..;;-. v.in f;i--r ftlminr. X 15. Fo. 4, |*t>n'i.Mii< .( .i f ,'*rnV>i-i. ,->| *-*-:iin irnt tlr- rtimrin of . |.f'itral |l*o lltirf.* ,( ;ir*a In il.' ( fr ...I-Ikih it. jpr *>d ilt tiM-ty |*na-Lri| l.lwl. It** li-.if lo if r ficl.i if..-* not nkiim. .Mi/.*rin rn| Msinitt^. X ST0011702 STOO I 1703 AXI fl.M H Mi -|.VlJ 'I (lint hyaline mum* tiv. -ti- in .|i g.n. intinn, like nr.-mi-, nfl.-r- \'iv f " ' -'hie conditions fur (lie accumulation of calcium d. j*it- (I!y<I. I!*.>.(). Clinical Fiati(t in Cni* of I'l' neat Calcification III gcneml, it appear.* (Iml itu- pie. cure of calcifir plaque* in the )! m;n* dor* not hi rncli cause any subjective or objective syiii|lm.< or Sinn- in die liiajyrily of ease* tlie lesion* nrc not n5*oeiaU'd with nny putIuiIo;i*:iI rhangc* in Die lungs or any oilier organs, clinical disease proper drives not -ccm lo be involved (Kiviluoto, 1900; Mar.-ova, 1901; Meurmaii, 1900; Jlaimio, I9l>0). Pulmonary fibrosis is a relatively common accompaniment, however, in pailienlnr when (lie plaque# arc so heavily calcified as to 1>c visible on ro< nlgc'iingi urns. Tn the 12G cases descrilicd ly Kiviluoto, slight puhnonary fibrosis was d.-Urlcd in 12<7c niul marked fibrosis in a fiutbcr 127c- -Ml Mibj.-rl* who bad been occupa tionally c.\jx*-ed to nslwslus* dust at aslK-.-tos mines or mills were omitted from thi.l series. Of (be 03 subjects with pleural enlcificalioiis more thoroughly studied by Rnmiio, only two showed rneiilgciwgraphically discernible fibrosis of tbe long, and these subjects bad !cin working at nn asbestos mine. If.iunio states, luma ver, dial- in rase# in wbirli extensive pleural calcifications arc present on (lie roent genogram, fibrosis of die lung may l>c difficult to distinguish because it may t>c masked by tlie calcification. On tlie other hand, in SclikolTi (I9G3) extensive suics comprising insulation workers in New Yoik, pleural calcification was almost invariably n-soeinji-d with pulmonary fibrods varying in ih gree. Tlie discrepancies may thus obviously he due to differences in comjiosition of the series, i.o., whether they consist of oc cupationally or environmentally exposed subjects. Cnlcifc Pleural Plaque* mu/ l)ijju*c Mdathcliowa It is striking that an association lietween nsbestus cxpoMiiv on the one liniul and on tbc otber two different kinds of pleural hsion, i.c., benign calcific dis seminated plaques in one study and malignant diffuse mesothelioma in another, was observed at roughly Ibc same time by investigators working indcpeiuh-ndy of each otber in different parts of tin* world (Jacob and lloldig, it)3.*; Wagner, 19-30). Noth these lesion.* arc often associated with nonet rupational, obviously very slight ashes ton ,\pnMiro. Another feature in common scetns to lw Unit the conditions only became manifest after several dermic# have elapsed -incc the first \|>osure to a.-l-Mo* du-t (Kiviluoto, T9G0; Wagner ct ul., I9G0). Moreover, bi'tb '< -1*:\- have . i: fi-r i -. d n< o..n -v-d tin- -amr rase PVei^. (O.'fi: W.-wnor, I'JGO; I_aw-on, 1903; Fntickuap cl aL, I'JOt; CrtcoI ct at., I'lii.i; tiouuuanr at., ICfiG; Ca-thtnnn, I9G71. From the histologiral standpoint attention nnv, in addition, t-e drawn to tbe stnu-tural risenibhuire bitwecn tlie stroma of benign hyaline -eh-rotie phtirnl plaque# and rlilTu^c mesothelioma of the .-croud main group, tbe filnutic tyjie (Ifouribane, I9GG). Numerous studies published in difTeieul parts of the \eorM aigue in favor of a significant rnircl.it mu b.lw.vu the dr\clnpm.-nt of mi-nth.-Ii.m,a and d,, -I.w <\|'"-,uc. In Foulh Afiira, Wagner ct at. (ItJfiO) wan- (lie (ir.-t I,, draw ail,,,lion to this n lafion-liip, and somewhat later similar rr-nlt : wa re up.n-i.-il be Timm-un ST0011703 S T 0 0 I1704 42 l.WHI <*. Mi l II>1 IN (JOr.'J). ('uni infill;' ivid<n<' )- i - inmt-nver l*m prodtircd hv Owen (10f> [J; 1 loitriltiiiM- (J!X1I), ;ui' I N-uli'.':-( :.u.f Thom-on (IPGA) in Kngkmd; Klmo ft al. (MI0.*h in Xmlli lnl.ii. !; .-'i !'!.'ifi ft vt. (li'C'i) in V.S.A.; Konig (lfiT.O) and linitiM ii (IPGA; in Germany; and .M' Nnliy (IPO?; in rulifi. On tin- other hand, ;i ri ti i'-pi' tp i -Indy of a 10-ywr autopsy series fiom tlu- Ala Inin Jln.-pitaf, |m i fi.nn. d I.y iliv jm.-i-nt aitlliot in co-ojkrntion with Swedi-h pnthotngi-t- (I lii;o i*ti; i! it nt., IPGSi, gave no defiuiti proof of nn as-oeinlion between CNjKi-ure to n-li'-ln- d'i-i tunl tin- development of <tifTllc inerothelioina. Tliii* nett).h-m w.-i- d'-tected in 31 m-.. . Tn IS of ll.e-o, n.-licsto? bodies were found in flic fmij'i, in G c;i-i - in rih.tivc nli'iiidaiire. However, in ft conlrol ciic?* from the nunc ho-pital with tlx, .-nine romjui'iiion as regard- nge ft ml son, n-best o= Iw!ic wi re found in the liu,"- in 12 ra-e.-, in J in largo amount*. Since small iimuhcr* of a.-Uido- lio tii - in tin- lung- ore n frequent finding neccirding to nvnilatdc -lati-die; from difu vent port* of tl.e world, these results cannot, lie regarded as clear cviduiee of an :i-ociaiioti between asbestos exposure find incso- tlielioma. Tlic saim- imdetiaf wa* later romlgctiolngienlfy examined l>y Kiviluolo (jtcrsooal rommuniealioa 1907.'. Amo:.;; tlic case- with mesothelioma, two showed obvious and one nnr. it..in |dt ;:;n! cafeiT.r:.Ii.in. The rf*ult- cunri ii.in;-. t!..- i. hiinn-liip between n-bc.-to- expo-mt- nnd difl'me mcyotlieliniii.-i arc tlm- -niu'-u!:.t contradictory, find (lie same Applies to it-bcslo* cxjiOsiire and pleural plaqtii -. It .v i-ia- nlivio'i- that asbestos plays an essential part in tin- development of I .of b tin -i Ii.-ion-, but it nlso appears that other, as yel unktmun facto,-, po--iMy environmental, may be involved. These factors may, movenver, lie r. -pon-ib!.- for tin- development of licnign fpolyscrosili* fibrosa, GofIVrjr, cited b\ Hoivm.m. lP?7i or malignant changes of tlic pleurn or jicritoieum, porlinj>= even will.out -expo-urt to ndn-.-to*. Cartier's (I9G3) stftle- ment that tlie factor tlint can-. - a-ln-tn-i- i- not identical witli the factor caus ing calcific pleural plaques thoicfore s<-cm4 to hold good. Hut thi* unknown factor very frequently appear- to he n.--ociated with exposure to nsbcslo? dust. Theories. Conreiniug the I>titlii>jfi'f.*i of I'lx 'trnl I'lnque* 'J'he calcificntion of pleural phiqu. - i- readily accounted for hy tlieir histo* logical structure. Hyaline r-cl. rotic cullngennui connective tissue is precisely tlic kiiid of lis.-itc with low vitality that favor- the piecipitalion of calcium ions ns phosphate-. With inrie.i-iny age the fluid concentration in the tissues is lowered, with tin* result that ratciuni .-alt pivcipitntc? in the sclerotic tissue gradually increase. Tt i- inui-h mure difTindt to uiidei.-laiirl why and how hyaline ........... .. f 1 - -" d- I'm- i.-iri-.iy |n -nuip irrcciilarlv shaped arm? of t I H ' J 1' I I ll I . I I l.llnl 'tillli till!- ' ,1 , 'll \ |-f I ];i|> J ; I * l j 1 , l , On the a'-umptien t!:;.t -!- *T>i-! i- the only can-c of plaque formation, it nugU 1,1 - < i; -1 < ! il.- .-..u-.i'iv-.- m. chani-fM cr.n-i>(- of rlina-t niech.uiiral flirli."! IS). ;-.d ,f ,rt . pil.t; K|-.i';- I!1 ' t1 - Ihi- tin oiy pri -iij.|Mi-i- (hat t fu* a -I" i..- hi in- ' . - 11 , \ i- I t'l-":i.i alid -Mat'll the -Ill-far. of the p., i i. la I (,! in a a- a I V11 I 11 i :: in * *.. ; . i ' . .' t.. i`a.,'iy ini.'.. -|i-iiItlm- cmi-ing a Ghtini.uJ" pi- 'I'.* - irad , 11. .. i|- .,, - . I. f r. o'-, il-!,. i F>. fila a . ! -.. ; ! - ' '1 ,v I. v. I .|. r i(11 11ya !i11>- -i'[. iit| ie eiia- ST0011704 9G4>; >' rt nt. '>0) and from the Swedish ocintion bcliotnn, IV found i c.* from Iisbcctoa e rmnII 'ling to mint lx? I HlrtO* ivi looter flowed * * Ircstoa ? .^: -i-ntial r, tut .lorn rositi* urn or *tntc- f.irtor lii' In ly the i ion* .u s js tissue inline :i n:i STOO I 1705 amebtob Asn rtevRAL ruujur* 43 nerthr tissue in tlx* manner typicnl of war formation. Tliix liyjothmir is eompalil,)* with tin* pmhmiinnnt location of tlie plnnue* in those arm* of the (parietal pleura win-re the respiratory nmvrtncnt? nrr strongest (Kiviluoto, 1900). Although judicstow dust is found under the visceral pleura in only relatively moll amounts in advanced ense* of nubcstosis, penetration of lli pleura by asbestos dut is by no mean* imjjossihlc, since asbestos bodies protruding into the pfcurnl fhvtiy have Ix-en recovererl from the surface of the lung* (Meurman, I960). Likewise, die*to* filers, though no ndxYtos bodies, have Ixen found in parietal pleural plaques (Houriliane, 1900). On the other hand, the presence of n*l>estoe fibers in tlx? parietal pleura doc* not necessarily, mean that these fibers have migrated from the tunga through the pleural ravity. Asbestos dust has been recovered from many organs, e-g^ tlx* kidneys, bone marrow, liver, ndrenab, spleen, and gastrointestinnl tract (Selikoff ft of., 1`JG.H. lienee it scents |xjs#iblc that nslx-stos fillers are transported to the inrietal pleura with the blood stream or via the lymphatics. Another argtt- i'_-metif agarnsl the" mctfi61W^SWtt0Wtlp^dw'tlfnt dhe latter presuppose* a - - ^S^prelliHfaary stags of.fihrwdw%x*udation, nml according to patho-anatomicnl experience fihrinou* exudation as a rule leads to obliteration of the pleura! cavity. v -v.i... So far, no evidence has lieen produced of either fibrinous exudation or any other preliminary stage of |dnque formation preceding the hyaline sclerotic coonectivc- tissue stage. In addition, plaque* occur admittedly when the pleural cavity i* unfused or, if it i* obliterated, n* a rule nt those sites where it In* remained 0|kii. Of purely chemical theories regarding the pathogenesis of pintthat offered hy Ijiw.'Oii (l%3) seem* to lx- the most precise. Lawson suggests that the ningru-Mimi contained in n-liestos and tale may lx* rc?]K)m>iblc for cnleifieatioo by nrlivnting nlkalioi- plio-'hala.-e. A combined elTeet of phy.*irnl and chemical factors i* proiipjxjsed bx- the theory advanced hv the pre-cut author (Meurman, IDfiO), according to which the sites of predilection of the phupie* are tho>o nrvn.* of the parietal pleura where tlie greatest amount of stretching is caused hy the rrspirutorv movements. The cfTecl of n.*1>o>ios ns a contributory factor would consist of altering tltc comixisitiou of tlie fluid pacing from tlie lung* to tin* pleural cavity. This change would lx due to infrapttlmonary damage caused hy the nslx-idus filx-rs, com parable with niirrulicmnrrhnge*. Ami hemothorax is known to Ik- the most com mon color of pleural calcification. So far no eonctii.-ive evidence ha* freon advanced in .up|x>rt of any theory eoiicernirig the pathogenesis of plaque formation. "ii. if "i'-al i lb. ' the n * .ii. 1 hi* paper i- a review of recent literature enueeniing ealeifie ph-tira) phupie*. It i* e-tah|ihetl that multiple ealeifie pleural pl:i<|iie* are a rare nrcntjjeh- ogtapliic finding in all (Hjpulalioti groii|t> except milter,, arid industrial wculni* ale* hand!, a-li, (ale. \ amr wort hy cniieetii rat inn of ca-i- -homing pla>|>ie- ha- al-" hill, nl,.,., e.-,| in pn; ml:, t ion- livinu in (lie vicinity of ads.i,,. min. > 1 m rt:............ Ii Ivli freipretiey i,f pleural ralcifieat i.m ha- II-HI'II ItOlr f| v. li f ii Mir :in v :'f . *lr(. 1 \|u-nr. I,-in.- iim m-11 a I il. |-|. m.il - are a c.mru.ir. ST0011705 90/. I lOOiS. 44 UVKl O. MCl'KMAX autopsy finding, iui*t n urlnin regularity has been otwerml in Ibeir JoMttMfc. Anatomically and hWlologicully, 1 lie plaques correspond to fibiotie mrMfefcr although in most eases their ralclutn content la #o low thal vUitlc on rocntgonogrniiH. ]o industrial workers occupationally expos'd to asbestos dt lion w often associated with )>utinonary fibrosis. By contra, which slight exposure to adrestos dust result* from living in ai asbesto* deposits, or in the ncighborltood of asbesto* facte not a* a rale associated with pulmonary fibrosis. If thl* eoi U to mild that it cannot bo demonstrated rocntgenographl manifest Hsclf as respiratory insufficiency. In addition to a*b some unknown endogenous or exogenou* contributory factor blc for pleural plaque formation. The presence or absenc* < vlotwly tlcelslvc In respect to the development of plaque*. In i eertain art** this hypothetical factor appears to be capable c pleurnl plaques even without exposure to asbestos dust. 7 jdeural plaques is as yd oKsrure. KKFKfIKNCL.'S Axsncn, >1. (tOC?). Pin. t II. urjvrrfcdtnnujru piliofnorr.onidi flirt Areh. Gt<rttbci*firof. )9, 10*120. Krc, J, PCiocriim.m, It, tNu \Viu;m*.v. J. (1C*61). Cantiopulmoiui wortet# dcali'ip nilli a:V-`n>i ,in-l fl,i*ncol. 7Uorx 19, 77-77. JlottMtX.v, A. (1927). t't-r l'uty.H ro?it: chr.rnicA W)io*a und \T-r tho<T4 A,rh. r-il.f.l, Av.tt. 11,.;..'. KVn. Mel. 201. TOO- T79. Hor, \W (193.1). "A TV of Piiifmlo'y,'' mth edition, Kimfitc CUktiui, I*. (1/<o). i-i Sevtioa VI. "Clinical studies of p Amm. X.y. Ar<uf. Se\ 132, 3*7 3SS. C.im/viv, Tt, t.'o Vm i-cw k, (!. (!W), Cnsc rreoref* of the J 1 tu.pilnl. C'.i-'r -M/siT. A\ r. >>). /. .l/W. 27G, 330-337. ]f. G. (1902). Kii.>' (in;.dojipdf* itifc TTcuthv FrunfQrnilt. 07, SI2 SIT. v. e, MiC'umim, W. T. K, xn V.,*:, O, I,, flOM). )Nf! the |>ti ura nri.l .vli.trn. fln't. M'-t. J. I, 37)-3.VJ. Ektk-kx.u>, J. ). im, Sun tin:, tV. J. (19<W). l'/ rilonval tumour* i M. Mtti. *1, 20-31. rV:u*r, tl. (I93C). t'iirr ifo;>p. I'lptir.ivcikalktingcn infoijpc I viitnup n. fort-rKr. f.'n. i.j. . So, lfi-3.',. :>l r.. IM> /WmoNArj, : U '!>.-n r ,l.if..-.,iin,, r.r t!,.- vlv,,ri . .|0, 313 J.'J, fr>ST. J, Ou*.:, J, asp Mam.,, p. \-\ (lo.vA. .VIk-jIco-. wilh rtnirl c, inoil.itinn norloi-. I)I. /;,)/. 3, 2U2-2PJ. 0*vv,t.M, c. noi',). I.r r.iHr-.ifimii | Imri.-lH- mil* t.nrmnomnluu 379 (KS. CTiiiv/i. T, M'trn -.i, H . imi I'lillrl. f. f 1 ''.i), hil.il in'. r>r Mi' , V- ./ / ... as. M .. > v,,. 1 . ............ f ml tn- - .'1,-1:-, .! >.. /' ' ,N" *' ' I< < A-l IppIii. in I A-li. ,-ln- tnnll. . Ifni r.rn i\i . li n f: r ;n ST0011706 sT00 I 1707 y * f tr * l I r -j- T rk' -- AKTUB A.NO I'li.tKAI. M-WJU M ' <14 l_, an* irwn UM5, r. C. (itaah -uiJ t-uUifk<u ______ i (*f rt|u>vre lo uU'*(ni. Artl. .VlJ. /. I, HW* 1071. .)IniKla.v if.-k.vl ratarlrrirlitkfrh j.kunllntrh iv'n H olyvn*rUtvn hkraje JihUra. RoihMg r*f>erk. IS, KWI11. n-Bt(rttolni< a-jwrt# of aU-Ho*i. Am. J. A1** */*-.,./. ftn>linm ts, n^W. (19M). Hie rOnlcw)n*i*H* KtHnj.JikrilKMirn At T.untpniA1>rinm. 83, 15-30. Flrarat ralnfinlwi* aa A romt^-mAuve of "n-ocoipa(ioiv*l iljcrlari*. .left JWW. StppL 1*4, 1-87. , J. a> StiATiw, J. (1908). CKmcal, railkjlonknl am] pliytioVtfiea) _____ /afrW Med. 117,SU-S18. KfletM, rfW X&trtme. Arch. GavvrbepafAof. GtardH-Apf. IS, 159-201. t i tUu.NMt V. OMS). ObmTTwlloc* on alntutpherie uir pollution a^dKln. .V.)-. ArW. Sri. IM, WW Uvmr, J. f. ` (TMS). PVoml ealriValioe an * dfen of vbratam*. Cb. Rodiol. 14, 111-117. Moteri, D. (TWO. Dnlnj nr .llieletie 4rr IVantmfaillninpa. Z. T*Ixrk. 121, 350-534. MmvAT, ). (1000). .lArflot bodirt ami plfciral plmjort in a Finnish n.*rir* of auln|jr <*. Arln PothoL Microbiol. Scomd. 5ppt- lMg^lWMfNu.Tr, J. C. (1009). Mali(tTuint plrnral 'mMUmm In an a*be*toa worker. .1/rd. /. Amfiwtta X, MS-OSI. MCun, FT. (1098). Oat rchwer* Forme* 4M~*iW Mam. tm "Din StnoMuo*encrLmnk-- itnfr*" (K. XT. JStle* ami XV. KVwIcrkoller, edK>.ToL3,vp.501-381. Steinkoj>fT, DamwlfliU. MCun, II. (1901). PVnm-rrfcaltimtr* W 4tC',UbcWaabhm|r. Railiot. Diagn. 3, 33-3S. .N'rrr, W. (1003). ijr PlrmavcL Ikanst-n rm AJlef. Forttchr. Rocnlgrnttr. 09, 633- 838. Nr'H0vr% M. 1-, ana Tiiomtsox, II. (1905). Xfrwrthcliomii of plnirA mid. |w-n'U>-.< ti(n forto*in< expomr* of n-U--lo* in tI*o T/wlon am. Brit. /. fad. .1/ed. 22, 30I-2GS. Oonrircrrr.x, S. F, TuraoN', C. P. ax* St-cra-CarMi:*, C. K. (1001). Cnb-ifxd |k-untl plaficr* in :ul)(i4o*. Prrtr. Mine .I/rd. Otfietf* Ar. 10, 196-501. Owcx, XX". O. (1964). DilTitfr nw-Aolltrltoma and expomifn lo nrln^lm dii-l in tit*- MereeynMe arm. Ifni. Med. J. 3, 211 -2IS. ft if mo, X*. (1906). Ocetinrnrv of utnifuil ploiiml eakifiealion in Finland. .4**. .I/rd. Intern. fi**, A*p/d. 47, ) -SI. ftonxrcu, A. C. (TOO)). CVr die KoimMrnt vo*.. Aabatw rnnl Merot Minot, Zht. At!g. PaiM. .!*<. ias, no. SrutoiT, 1. J, Oman, J, ann IhMMaxt, K. C. (TOSS). Ralalion lelrrm rxpoAuro to athe->toa an*l mr>lh. lk>ma. .Yrir Kngl.J. MrH. ITt, XQ0-X6T. FcuKorr, I. J. (196J). The occnnvncr of plnrml eaUfimtion nmunc adn-rtoa inhibition worker*. .4a*. .Y.F. .Imd. Set. 132, 351-367. J1'1* XX, Smith, A. R, .tsn OmxMt'w, I,, (1013). Do rluri Katanl in lirmolito lain urinina. .(<. J. /local* n/. /.'ndiurH FAr.tt>jy. Xurl, Mcrl. 40, 11-29. Makn.o'0, P. axb XX mm3, J. C. (1961). Diffiuc pfcmral mcvothcliomaa in tarth A fries. 5. .I/.imm .1/rd. /. 35, 25-34. Sxrrrt, A R. (1052). ITrnral mleiflratton mailiNf from expovm* lo- eerlain dual#. Ana. J. Roentgenol. Rcn/ium Thcmpf .Yurf. ,1/r-/. 67, 373-3S3. .-itM., e*. yi.mi iNitu.u. , :.......; .... I m, ,i 1 ,.Mi .mil itii to athrttoa. Bril. J. Di'tturt Cheat 39, IX-133. In.;.*;; f.;!! ^ j''.it TrioMmx, /. O. (1063). XfrutMioma n[ |>|rnra' or iwrilnminn nm4 llmllrd ha-nl abcjtrmv 5. A [net* .Iferf. J. 30, 759-760. XX.tnxra, J. C. (1900). Some jvitbologiral a*prrt of asbr*tON< in the Union of Sootli Afrira. in `TiotTfrlinp* of the Pnnimocoiiiori* Confi-rvorv" f.X. J. On n-li in, e.1.) Ji>lunn<-I<ur* I9.A pjt. .773-75?. Onirrfiill, f^mfon. U'lr.N,., J. c, Rr.r.o:., C. A., tve Miavinxit, r. (10a>. DifTn-r j.k mil mm.ili. rmt .ut-l al.lo < A|AMnrr in ||,c N'nill. W, ,t C\ir<. Protinrr. Pnt. i. M.-.f, 17, Xrl 77\ ST0011707 ST0011708