Coal workers' pneumoconiosis (CWP) progresses to 'progressive massive fibrosis' (PMF) when the lung lesion size exceeds:
- A 1 cm
- B 3 cm or category B/C on ILO classification ✓
- C 5 cm
- D 0.5 cm
Correct answer: B. 3 cm or category B/C on ILO classification
Explanation
Progressive massive fibrosis (PMF) is defined as conglomerate opacities > 1 cm in CWP, categorized as A (1–5 cm), B (> 5 cm but less than upper third of lung field), or C (> upper third) on ILO/NIOSH classification. Some sources use > 3 cm as the threshold for PMF with significant functional impairment. Category B/C represents the progressive, often fatal stage with severe restrictive and mixed ventilatory defect.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.