Fig. 2

Histologic features of a case of polytetrafluoroethylene (PTFE) exposure-induced pulmonary granulomatous lesions (a and b). a The specimen shows mainly small airway- centered granulomatous micronodular lesions (arrow). b Higher magnification of the specimen shows multinucleated giant cells containing amorphous transparent particles (black arrows). c Polarizing microscopic finding of the same multinucleated giant cell found in Fig. b reveals the birefringent particle (white arrows). a to c Hematoxylin-Eosin stain (Magnification: A: × 40, B and C: × 400). d Transmission electron microscopic feature show intracytoplasmic electron lucent amorphous materials (asterisks) in the histiocyte. e and f Scanning electron microscopic feature (e) and comparing element mapping of fluorine (yellow) reveals the presence of fluorine in the pulmonary lesion. g The scanning electron microscopic feature of the lesion revealing fluorine in Fig. f shows multiple round to oval granular material measuring 2–6 μm. (Original magnification, d: × 3500, e and f: × 500, g × 5000). h: Energy-dispersive X-ray spectroscopy (EDS) spectrum of a particle in a round particle (target 1 shown in Fig. g) found in multinucleated giant cell showing a prominent peak for fluorine (F) but with other associated elements such as carbon (C), and oxygen (O)