Study Syllabus for Classification of Radiographs of Pneumoconioses
Section 3: Pleural Abnormalities (Continued)
When present, diffuse pleural thickening is recorded separately for the right and for the left hemithorax. Place a check in the appropriate blocks in 3D for both in profile and face on components. If none is present, check O. If diffuse pleural thickening is present, check R or L or both to indicate its distribution. If R or L is checked, there must also be a check in each of the remaining boxes in the section. For example, mark O if calcification is absent on both sides, and indicate the presence, extent, and width (if required) of the pleural thickening on each side.
Conventions for classifying extent and width are identical for localized plaque and diffuse pleural thickening. Mark 1, 2, or 3 and a, b, or c as appropriate to describe the diffuse pleural thickening identified.
Pleural thickening along the chest wall may be circumscribed (plaque, recorded in 3B) or diffuse (recorded in 3D). To distinguish chest wall plaques from diffuse pleural thickening, it is helpful to remember that plaque tends to spare the apex and costophrenic angle, whereas by ILO Guidelines, diffuse thickening must involve the costophrenic angle. The minimum width of in-profile plaque or diffuse pleural thickening to be recorded is 3 mm.
Radiograph #17A shows these normal apical pleural shadows (arrowheads), which often are symmetric and thickest between the lateral first and second ribs. Similarly, one should be careful not to confuse normal symmetrical apical subpleural fat densities, when visible, with pleural thickening.
Significant thickening of the apical pleura should not be recorded in Section 3 but should be checked in Section 4B (see below) under the symbol at.
In Radiograph #17B note that the muscles produce soft-tissue densities frequently oriented obliquely from top to bottom in a lateral-to-medial direction (arrows). One should be careful not to confuse the normal muscle shadows with pleural plaques.
In Radiograph #15D, is another example of diffuse pleural thickening on the right. It may be a result of asbestos exposure, but is less specific than plaque and may also occur along the hemidiaphragm.
When it does, there is coexistent costophrenic angle obliteration. This diffuse pleural thickening along the hemidiaphragm may cause the hemidiaphragm to appear ill-defined. If this loss of definition involves more than one-third of the affected hemidiaphragm, the symbol id in Section 4B should be checked.
The width and extent of in-profile diffuse thickening and the extent of face-on diffuse thickening are measured as described above, similar to pleural plaque. The diffuse pleural thickening seen in profile along the right lower lateral chest wall is of width a and of extent 2.
In Radiograph #18A, in-profile diffuse pleural thickening along the right lower lateral chest wall is of width b and of extent 2. The right lower and middle zones in Radiograph #18A and #18B demonstrate a veiling appearance of diffuse thickening face on. In #18B, the extent is 2 and width b on the right and extent 2 and width b on the left.