A worker in a silica dust-exposed environment develops progressive massive fibrosis (PMF) with bilateral upper lobe fibrotic masses and eggshell calcification of hilar nodes on CXR. The ILO classification of pneumoconioses would categorize this as:

• A Category B or C (large opacities of progressive size up to upper zone) ✓
• B Category p (small rounded opacities <1.5 mm)
• C Category A (large opacity 1–5 cm)
• D Category 0 (no opacities)

Explanation

The ILO International Classification of Radiographs of Pneumoconioses classifies large opacities (PMF) as: Category A (1+ opacities, total size 1–5 cm), Category B (1+ opacities larger than A but combined area ≤upper zone), and Category C (1+ opacities exceeding the combined area of the upper zone). PMF with bilateral upper lobe masses would typically be Category B or C depending on total area. Small opacities are classified as p/q/r (rounded) or s/t/u (irregular).

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.