BACKGROUND In humans, wood dust is a carcinogen. Indeed, a strong association between wood dust and lung cancer risk has been reported in woodworkers, as well as in the general population. CASE REPORT The patient was a 58-year-old man with follicular B-cell lymphoma. In the 10 years preceding the cancer diagnosis, he lived within 1/4 mile of a paper mill, where wood was processed. Computed tomography of the chest, abdomen, and pelvis revealed right hilar, mediastinal, abdominal, and retroperitoneal lymphadenopathy, bilateral pleural effusions, and a large soft-tissue mass infiltrating the small bowel mesentery. Analysis of the pleural fluid revealed the presence of a web of thin filopodia-like filaments, which trapped clusters of mesothelial cells and atypical lymphocytes. Single tubular filaments, morphologically similar to tunneling nanotubes, were seen originating from atypical lymphocytes and reaching neighboring cells. Furthermore, long, thick, cylindrical fibers of unknown nature, probably from the external environment, were also observed. CONCLUSIONS Because the patient lived in an unhealthy environment for many years, the possibility that his clinical condition was related to exposure to toxic emissions should be entertained. Considered in this context, the foreign fibers in his pleural fluid could be a direct consequence of inhalation of contaminants in the polluted air.