PURPOSE: To evaluate the fluorodeoxyglucose positron emission tomography (FDG-PET) features of progressive massive fibrosis (PMF) in patients with pneumoconiosis. MATERIALS AND METHODS: FDG-PET and chest CT scans were performed in 11 patients with pneumoconiosis and PMF on chest radiographs. We evaluated the size, location, maximum, and mean of the standardized uptake value (SUV) for the PMF. A fine needle aspiration biopsy was performed in patients with a mean SUV of > 2.5 to exclude lung malignancies or pulmonary tuberculosis. A Pearson's correlation was performed to determine if a correlation exists if between the sizes and the mean SUV of the PMF. RESULTS: A total of 19 masses from 11 patients were located in the upper lobes (bilateral in eight and right in three). The sizes of the lesions ranged from 1.3 to 6.4 cm (mean = 3.6 cm). The maximum SUV was 0.5 to 8.1 (mean = 3.8) and the mean SUV was 0.4 to 5.9 cm (mean = 2.9 cm). Lung malignancies or tuberculosis were not identified in the 12 lesions (63%) with a mean SUV of >2.5. The sizes of the PMF did not correlate well with the mean SUV (r = 0.225). CONCLUSION: FDG-PET scans can show PMFs as regions of increased metabolic activity (mean SUV, 2.9) without evidence of lung cancer or pulmonary tuberculosis. No correlation between the sizes of PMF and the mean SUV was found.