~N\~LKOSMESI4~. R~SF.AKCH11, 128-134 (1976)
The Visceral
Pleura
in Asbestosis
A. SOLOMONAND I. WEBSTER National
Research Institute for Occupational Research Council, P.O. Box 4788,
Diseases of the South African Johannesburg, Soath Africa
Medical
Received January 19, 1975
The visceral or pulmonary pleura is a serous membrane that covers the surface of the lungs and lines the fissures between the lobes (Gray’s Anatomy, 1973). The fissures are seen as a white hairline shadow (Simon, 1971), and their average thickness is about 0.2 mm on routine chest radiographs (Felson, 1973). Deviations from the normal thickness of interlobar fissures is easily assessed in chest roentgenograms. Postero-anterior, lateral, and oblique chest projections will produce an accurate radiographic assessment of interlobar fissure abnormalities. This paper emphasises that lissural thickening accompanies asbestosis. METHODS AND MATERlAL
Thirteen patients with a known exposure to asbestos (in that they were all engaged in the mining or milling of the material) had routine chest radiographs in a postero-anterior, and both right and left 45” oblique chest views. A grid Bucky was used in all cases. As accurately as could be determined, none of the group had complicating disease. There was no clinical reason, other than asbestosis, for the lissural thickening. RESULTS
The radiological features are listed in Table 1. A group of 72 patients, with low dose asbestos exposure showed no evidence of visceral pleural change. In this group, exposure histories varied from 3 months to 30 years. The low dose group was a group of management and executives. They had, at some stage, worked at an asbestos cement factory and had been exposed intermittently. Thirteen patients with a significant history of asbestos exposure had evidence of pleural and/or parenchymal asbestosis. Of this group, three patients had minor fissural thickening as the predominant radiological feature. (One patient had, in addition, a calcified right diaphragmatic plaque which radiologically supported the diagnosis of asbestosis.) This patient had a history of exposure to asbestos of 37 months, working in an asbestos mine. This exposure antedated the radiograph by 16 years, 5 months (Fig. 1). Another of this group had a total exposure history of 30 years. The third patient had had 6 years of continuous asbestos exposure, the initial exposure occurring 265 months before. Ten of the remaining cases had histories of continued asbestos exposure. Of this group, the shortest period of exposure was 11 years, and the longest 27 years. All of these remaining ten cases had radiological changes of the lungs in keeping with asbestotic fibrosis.
128 Copyright All
rights
0 of
1976 reproduction
by
Academic in
any
Presr.
Inc.
form
reserved.
THE
VISCERAL
PLEURA
IN
129
ASBESTOSIS
The two patients with total exposure histories of 4 years, 9 months, and 2 years, respectively, had initially been exposed 24 and 20 years before. They therefore had an adequate time lapse since exposure for a sufficient concentration of asbestos fibers to produce significant reaction (Sluis-Cremer, 1970). One patient with serial radiographs demonstrated progressive minor fissure thickening as significant asbestotic parenchymal X-ray change became evident. (Fig. 2). The lung changes were considered consistent with the X-ray diagnosis of asbestosis. The ten patients with X-ray changes of asbestosis had, in addition, radiographic evidence of visceral and parietal pleural thickening. Included in this group were two patients with evidence of calcified parietal plaque formation. The lung changes in these ten patients were considered severe X-ray expressions of asbestosis. The pleural changes (visceral and parietal) were acceptable additional evidence of asbestosis. DISCUSSION
Many observers have drawn attention to the occurrence of fibrous (noncalcified) pleural plaques as part of the radiological spectrum of asbestosis (Anton, 1968; Leathart, 1968; Sheers and Templeton, 1968; Fletcher and Edge, 1970; and Thomson, 1970). These descriptions are confined to parietal pleural changes. In fact, TABLE Case
Age (years)
2
56 40
3
41
4
68 41
6
40
7
46
Exposure history Total 30 years. Total 37 months, initial 197 months previously. Total 6 years, initial 265 months previously. Total 11 years. Total 57 months, initial 285 months previously. Total 27 years.
1 Asbestotic X-ray changes of lung
Pleural thickening
Nil Nil
Minor fissure Minor fissure
Nil
Minor fissure, calcified right diaphragmatic plaque. Minor fissure, bilateral axillary pleura. Minor fissure, left pleural calcification. Minor fissure, right major fissure, bilateral axillary. Minor fissure, right major bilateral axillary. Minor fissure. Minor fissure, left major. Minor fissure, bilateral axillary. Left major, bilateral axillary. Minor fissure, bilateral axillary, left pleural calcification. Minor fissure, bilateral axillary.
+ +
Total 2 years, initial 20 years previously. Total 24 years. Total 22 years. Total 20 years.
+ + +
8 9 10
50 41 unknown
11 12
50 44
Total 25 years. Total 19 yeas.
+ +
13
53
Total 25 years.
+
130
SOLOMON
AND
WEBSTER
FIG. I. Right fissural thickening with a calcified right diaphragmatic
plaque.
Meurman, in 1966, maintained that pleural plaques are confined to the parietal pleura. Various authors have directed attention to interlobar fissure thickening accompanying asbestosis (Kiviluoto, 1960; Solomon, 1970; Fletcher and Edge, 1970). Despite this, the ILORJIC classification makes no differentiation or allowance for recording this separately from parietal pleural reactions. In the cases presented, fissural thickening is prevalent in those cases with the more severe asbestotic manifestations. It remains difficult to differentiate plaque formation from pleural thickening radiologically. In asbestosis, diffuse pleural thickening rarely calcifies. Any fleck of calcium in an area of thickening may be assumed to be in a plaque (Fletcher and Edge, 1970). It is worth noting that calcification in visceral pleura appears to be unrecorded. The assumption that plaque formation in this region is uncommon seems justifiable at present. There is, however, no reason why visceral plaques should not occur.
THE
VISCERAL
PLEURA
IN
ASBESTOSIS
FIG. 2. Right visceral fissures thickened with radiological
evidence of asbestosis associated.
131
132
SOLOMON
FIG.
3. Right
fissural
thickening
AND
WEBSTER
as the sole radiological
evidence
of asbestosis.
‘I’HE
VISC;F.RAL
FIG. 4. Fissural thickening in association asbestosis present in the lungs.
PIXL’KA
IN
with right axillary
iSSBE.5
pleural
133
1 OSIS
reaction.
Diffuse
X ray changes
of
CONCLUSIONS
Visceral pleural changes may occur in asbestosis: (1) as the sole radiological evidence of exposure (Fig. 3), (2) in conjunction with parietal pleural reaction (Fig. 4), (3) in association with parenchymal asbestosis (Fig. 5), and (4) as a feature additional to parenchymal and parietal pleural asbestotic manifestations. The severest X-ray abnormalities, of lung substance as well as pleura, occur in men who are heavily and continuously exposed to asbestos (Harries, et al., 1972). It is therefore not surprising to find interlobar pleural reactions in such patients. The three patients with shorter histories of continuous asbestos exposure probably reflect that there had been an adequate time lapse since exposure with the retention of a significant concentration of asbestos fibers in the lung field (Sluis-Cremer, 1970). Oblique 45” chest radiographs in association with the routine views enhance the assessment of fissural thickening. Visceral pleural reaction is progressive in some situations. A larger study is currently in progress to determine the actual dose relationship of visceral and parietal pleural thickening as well as parenchymal asbestosis.
134
Fro.
SOLOMON
5. Right
tissural
thickening
in association
AND
WEBSTER
with
X-ray
changes
of asbestosis
in the lungs.
REFERENCES Anton, H. C. (1968). Multiple pleural plaques. II. Brir. J. Radiol. 41, 341-348. Felson, B. (1973). “Chest Roentgenology.” W. B. Saunders, Philadelphia. Fletcher, D. E., and Edge. J. R. (1970). The early radiological changes in pulmonary and pleural asbestosis. Clin. Radial. 21, 355-365. “Gray’s Anatomy.” (1973). (R. Warwick and P. L. Williams, Eds.), 35th ed. Longman, Edinburgh. Harries, P. G., Mackenzie, F. A. F., Sheers, G., Kemp, J. H., Oliver, T. P., and Wright, D.S. (1972). Radiological survey of men exposed to asbestos in naval dockyards. Bn’t. J. Ind. Med. 29,274-279. Kiviluoto. R. (1960). Pleural calcification as a roentgenologic sign of non-occupational endemic anthophyllite-asbestosis. Acra Radiol. (Stockholm) Suppl. 194. 167. Leathart, G. L. (1968). Multiple pleural plaques. Brit. J. Radial. 41, 71-72. Meurman, L. (1966). Asbestos bodies and pleural plaques in a Finnish series of autopsy cases. Acfa Path. Microbial. Stand. Suppl. 181. Sheers, G., and Templeton, A. R. (1968). Effects of asbestos in dockyard workers. Brif. Med. J. 3, 574579. Simon, G. (1971). “Principles of Chest-X-Ray Diagnosis,” 3rd ed. Butterworth. London. Suis-Cremer, G. K. (1970). Asbestosis in South African asbestos miners. Environ. Res. 3, 310-319. Solomon. A. (1970). Radiology of asbestosis. Environ. Res. 3, 32&329. Thomson, J. G. (1970). The pathogenesis of pleural plaques. In “Pneumoconiosis-Proceedings of the 3rd International Conference, Johannesburg, 1969.” (H. A. Shapiro, Ed.), pp. 138-141. Oxford University Press, Cape Town.
The Visceral
Pleura
in Asbestosis
A. SOLOMONAND I. WEBSTER National
Research Institute for Occupational Research Council, P.O. Box 4788,
Diseases of the South African Johannesburg, Soath Africa
Medical
Received January 19, 1975
The visceral or pulmonary pleura is a serous membrane that covers the surface of the lungs and lines the fissures between the lobes (Gray’s Anatomy, 1973). The fissures are seen as a white hairline shadow (Simon, 1971), and their average thickness is about 0.2 mm on routine chest radiographs (Felson, 1973). Deviations from the normal thickness of interlobar fissures is easily assessed in chest roentgenograms. Postero-anterior, lateral, and oblique chest projections will produce an accurate radiographic assessment of interlobar fissure abnormalities. This paper emphasises that lissural thickening accompanies asbestosis. METHODS AND MATERlAL
Thirteen patients with a known exposure to asbestos (in that they were all engaged in the mining or milling of the material) had routine chest radiographs in a postero-anterior, and both right and left 45” oblique chest views. A grid Bucky was used in all cases. As accurately as could be determined, none of the group had complicating disease. There was no clinical reason, other than asbestosis, for the lissural thickening. RESULTS
The radiological features are listed in Table 1. A group of 72 patients, with low dose asbestos exposure showed no evidence of visceral pleural change. In this group, exposure histories varied from 3 months to 30 years. The low dose group was a group of management and executives. They had, at some stage, worked at an asbestos cement factory and had been exposed intermittently. Thirteen patients with a significant history of asbestos exposure had evidence of pleural and/or parenchymal asbestosis. Of this group, three patients had minor fissural thickening as the predominant radiological feature. (One patient had, in addition, a calcified right diaphragmatic plaque which radiologically supported the diagnosis of asbestosis.) This patient had a history of exposure to asbestos of 37 months, working in an asbestos mine. This exposure antedated the radiograph by 16 years, 5 months (Fig. 1). Another of this group had a total exposure history of 30 years. The third patient had had 6 years of continuous asbestos exposure, the initial exposure occurring 265 months before. Ten of the remaining cases had histories of continued asbestos exposure. Of this group, the shortest period of exposure was 11 years, and the longest 27 years. All of these remaining ten cases had radiological changes of the lungs in keeping with asbestotic fibrosis.
128 Copyright All
rights
0 of
1976 reproduction
by
Academic in
any
Presr.
Inc.
form
reserved.
THE
VISCERAL
PLEURA
IN
129
ASBESTOSIS
The two patients with total exposure histories of 4 years, 9 months, and 2 years, respectively, had initially been exposed 24 and 20 years before. They therefore had an adequate time lapse since exposure for a sufficient concentration of asbestos fibers to produce significant reaction (Sluis-Cremer, 1970). One patient with serial radiographs demonstrated progressive minor fissure thickening as significant asbestotic parenchymal X-ray change became evident. (Fig. 2). The lung changes were considered consistent with the X-ray diagnosis of asbestosis. The ten patients with X-ray changes of asbestosis had, in addition, radiographic evidence of visceral and parietal pleural thickening. Included in this group were two patients with evidence of calcified parietal plaque formation. The lung changes in these ten patients were considered severe X-ray expressions of asbestosis. The pleural changes (visceral and parietal) were acceptable additional evidence of asbestosis. DISCUSSION
Many observers have drawn attention to the occurrence of fibrous (noncalcified) pleural plaques as part of the radiological spectrum of asbestosis (Anton, 1968; Leathart, 1968; Sheers and Templeton, 1968; Fletcher and Edge, 1970; and Thomson, 1970). These descriptions are confined to parietal pleural changes. In fact, TABLE Case
Age (years)
2
56 40
3
41
4
68 41
6
40
7
46
Exposure history Total 30 years. Total 37 months, initial 197 months previously. Total 6 years, initial 265 months previously. Total 11 years. Total 57 months, initial 285 months previously. Total 27 years.
1 Asbestotic X-ray changes of lung
Pleural thickening
Nil Nil
Minor fissure Minor fissure
Nil
Minor fissure, calcified right diaphragmatic plaque. Minor fissure, bilateral axillary pleura. Minor fissure, left pleural calcification. Minor fissure, right major fissure, bilateral axillary. Minor fissure, right major bilateral axillary. Minor fissure. Minor fissure, left major. Minor fissure, bilateral axillary. Left major, bilateral axillary. Minor fissure, bilateral axillary, left pleural calcification. Minor fissure, bilateral axillary.
+ +
Total 2 years, initial 20 years previously. Total 24 years. Total 22 years. Total 20 years.
+ + +
8 9 10
50 41 unknown
11 12
50 44
Total 25 years. Total 19 yeas.
+ +
13
53
Total 25 years.
+
130
SOLOMON
AND
WEBSTER
FIG. I. Right fissural thickening with a calcified right diaphragmatic
plaque.
Meurman, in 1966, maintained that pleural plaques are confined to the parietal pleura. Various authors have directed attention to interlobar fissure thickening accompanying asbestosis (Kiviluoto, 1960; Solomon, 1970; Fletcher and Edge, 1970). Despite this, the ILORJIC classification makes no differentiation or allowance for recording this separately from parietal pleural reactions. In the cases presented, fissural thickening is prevalent in those cases with the more severe asbestotic manifestations. It remains difficult to differentiate plaque formation from pleural thickening radiologically. In asbestosis, diffuse pleural thickening rarely calcifies. Any fleck of calcium in an area of thickening may be assumed to be in a plaque (Fletcher and Edge, 1970). It is worth noting that calcification in visceral pleura appears to be unrecorded. The assumption that plaque formation in this region is uncommon seems justifiable at present. There is, however, no reason why visceral plaques should not occur.
THE
VISCERAL
PLEURA
IN
ASBESTOSIS
FIG. 2. Right visceral fissures thickened with radiological
evidence of asbestosis associated.
131
132
SOLOMON
FIG.
3. Right
fissural
thickening
AND
WEBSTER
as the sole radiological
evidence
of asbestosis.
‘I’HE
VISC;F.RAL
FIG. 4. Fissural thickening in association asbestosis present in the lungs.
PIXL’KA
IN
with right axillary
iSSBE.5
pleural
133
1 OSIS
reaction.
Diffuse
X ray changes
of
CONCLUSIONS
Visceral pleural changes may occur in asbestosis: (1) as the sole radiological evidence of exposure (Fig. 3), (2) in conjunction with parietal pleural reaction (Fig. 4), (3) in association with parenchymal asbestosis (Fig. 5), and (4) as a feature additional to parenchymal and parietal pleural asbestotic manifestations. The severest X-ray abnormalities, of lung substance as well as pleura, occur in men who are heavily and continuously exposed to asbestos (Harries, et al., 1972). It is therefore not surprising to find interlobar pleural reactions in such patients. The three patients with shorter histories of continuous asbestos exposure probably reflect that there had been an adequate time lapse since exposure with the retention of a significant concentration of asbestos fibers in the lung field (Sluis-Cremer, 1970). Oblique 45” chest radiographs in association with the routine views enhance the assessment of fissural thickening. Visceral pleural reaction is progressive in some situations. A larger study is currently in progress to determine the actual dose relationship of visceral and parietal pleural thickening as well as parenchymal asbestosis.
134
Fro.
SOLOMON
5. Right
tissural
thickening
in association
AND
WEBSTER
with
X-ray
changes
of asbestosis
in the lungs.
REFERENCES Anton, H. C. (1968). Multiple pleural plaques. II. Brir. J. Radiol. 41, 341-348. Felson, B. (1973). “Chest Roentgenology.” W. B. Saunders, Philadelphia. Fletcher, D. E., and Edge. J. R. (1970). The early radiological changes in pulmonary and pleural asbestosis. Clin. Radial. 21, 355-365. “Gray’s Anatomy.” (1973). (R. Warwick and P. L. Williams, Eds.), 35th ed. Longman, Edinburgh. Harries, P. G., Mackenzie, F. A. F., Sheers, G., Kemp, J. H., Oliver, T. P., and Wright, D.S. (1972). Radiological survey of men exposed to asbestos in naval dockyards. Bn’t. J. Ind. Med. 29,274-279. Kiviluoto. R. (1960). Pleural calcification as a roentgenologic sign of non-occupational endemic anthophyllite-asbestosis. Acra Radiol. (Stockholm) Suppl. 194. 167. Leathart, G. L. (1968). Multiple pleural plaques. Brit. J. Radial. 41, 71-72. Meurman, L. (1966). Asbestos bodies and pleural plaques in a Finnish series of autopsy cases. Acfa Path. Microbial. Stand. Suppl. 181. Sheers, G., and Templeton, A. R. (1968). Effects of asbestos in dockyard workers. Brif. Med. J. 3, 574579. Simon, G. (1971). “Principles of Chest-X-Ray Diagnosis,” 3rd ed. Butterworth. London. Suis-Cremer, G. K. (1970). Asbestosis in South African asbestos miners. Environ. Res. 3, 310-319. Solomon. A. (1970). Radiology of asbestosis. Environ. Res. 3, 32&329. Thomson, J. G. (1970). The pathogenesis of pleural plaques. In “Pneumoconiosis-Proceedings of the 3rd International Conference, Johannesburg, 1969.” (H. A. Shapiro, Ed.), pp. 138-141. Oxford University Press, Cape Town.
