False-Negative 18F-Fluorodeoxyglucose PET/CT in Malignant Pleural Mesothelioma.

We report a diagnostically challenging case of a 77-year-old man who presented with shortness of breath and was found to have a large right hydropneumothorax with collapse of the right lung. A malignancy was suspected, but pleural fluid cytology and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT imaging were negative. He then underwent video-assisted thoracoscopy with biopsies of the pleura and chest wall which revealed malignant pleural mesothelioma (MPM). Older patients with early stage MPM are more likely to have false-negative FDG PET/CT results. Pleural biopsy is essential when there is clinical suspicion for mesothelioma, even with negative initial FDG PET imaging.