Fig 1.
Schematic representation of the exposure state at the acrylic polymer manufacturing and packing plant.
The polymer powder undergoes a reaction and accumulates in drums after two rounds of drying (production plant). The powder is then packed in containers at the packing plant. Some products are packed in Packing A, while others are packed in Packing B. Workers who were likely exposed to high levels of dust involved in the polymer manufacture and packing. Task B (Filling A, B) involves the highest level of dust, followed by Task C. Task A has a relatively lower exposure than Tasks B and C.
Fig 2.
Typical frontal chest X-ray image of Case 1.
Chest radiography (Case 1). The bilateral upper lung field decreased, and fibrosis was observed in the hilar (arrow) region. Multiple bullas are in the bilateral apex (round arrow).
Fig 3.
(A) HRCT image (Case 1). Severe central fibrosis was observed on the right upper lobe. Fibrosis involved the pleura, and subpleural bullae formation (large arrow) was observed. (B) Emphysematous changes (round arrow) thought to be related to bronchial obliteration are observed. The white arrow indicates the obstruction of the bronchus. (C) In areas of mild fibrosis, ground glass opacity can be observed. (D) Emphysematous changes and interlobular septal thickening (small arrow) are observed.
Fig 4.
Typical frontal chest X-ray image of Case 2, chest radiography.
The bilateral upper lung field (round arrow) decreased due to elevation of the lower lobes caused by bilateral upper lobe fibrosis and pulmonary apical bulla formation, and fibrosis in central hila and fibrosis (arrow) as well as bulla formation (round arrow) can be observed. The bilateral inferior lobes are lifted up to the upper portion because of the reduction in the upper lung.
Fig 5.
HRCT image of Case 3 with a definite lesion caused by polymers.
(A) Image of fibrosis of the bilateral apices. The severity of fibrosis is moderate, with ground-glass opacity. An area of the upper lobe showed focal emphysema caused by bronchial constriction. Some areas with peripheral bullae and emphysematous changes were also observed. (B) Image of localized emphysema of the right upper lobe. Central peripheral bullae formation (arrow) and emphysematous changes can be observed (Case 3).
Fig 6.
HRCT image of an early-stage case with a history of pneumothorax.
(A) Multiple bullae (arrow) of the bilateral apices. (B) Image of interlobular septal thickening (arrow). (C) Interlobular septal thickening and bulla (round arrow) directly beneath the pleura. Case with a history of pneumothorax. Bilateral centrilobular nodular opacity at the apices and numerous bulla formation are observed. Interlobular septal thickening is observed (arrow). This case had only polymer manufacturing experience and no packing experience (Case 4).
Fig 7.
HRCT image of an early-stage case.
(A) Interlobular septal thickening. (B) Interlobular septal thickening. Chest CT image revealing suspected polymer lesions. Bronchiolar and bronchial inflammations and interlobular septal thickening (arrow) are observed.
Fig 8.
Incidence of polymer findings on chest imaging according to different exposure intensities.
Proportions of exposure intensity and findings. (The CT results for packing workers (A, B, C) do not include the three workers who did not answer the question about exposure severity.).
Fig 9.
Magnified video-assisted thoracoscopic surgery view of the histopathological findings of Case 1 obtained by biopsy.
Case 1. Specimen magnified video-assisted thoracoscopic surgery view at left S1 + 2. Irregular foci interspersed (arrow) with perifocal airspace dilation (overexpansion) are observed.
Fig 10.
Histopathological view of Case 1.
(A–D) Medium-to-intense magnification of central lobulette fibrotic foci with reduced luminal obliteration and wall fibrosis. The basic structures of the lungs are preserved. Fibroblast hyperplasia with mild inflammatory cells and the absence of dust deposits are observed. (EMS: Elastica Masson Stain).
Fig 11.
Magnified video-assisted thoracoscopic surgery view of the histopathological findings of Case 2 obtained by biopsy.
Case 2. A magnified video-assisted thoracoscopic surgery view of the left S3 shows interspersed irregular foci, perifocal airspace dilation (overexpansion), and pleural and interlobular septal thickening (arrow).
Fig 12.
Histopathological view of Case 2.
(A) Medium-to-intense magnification of central lobulette fibrotic foci with reduced luminal obliteration and wall fibrosis. (B–D) Mild inflammatory cell infiltration with the overexpansion of peripheral airspace (B, C) and the absence of dust deposits (D). (RB: respiratory bronchioles, EVG: Elastica van Gieson).
Fig 13.
Magnified view of the histopathological findings of Case 4 obtained by pneumothorax surgery (top picture).
(A) Emphysematous bullae formation and interlobular septal thickening are observed. (B–E) Histopathological findings of Case 4 are shown. Medium-to-intense magnification of central lobulette fibrotic foci, reduced luminal obliteration, and wall fibrosis with insignificant inflammatory cell infiltration.
Fig 14.
Histopathological findings of Case 4.
(A, B) Fibrotic thickening of interlobular septa is observed.
Table 1.
Chest computed tomography findings (Synoptical table).
Table 2.
Breakdown of computed tomography findings.