A scanning electron microscopic study of diffuse mesothelioma and some lung carcinomas.

Seventeen cancers from lung and pleura were studied with scanning, transmission electron, and light microscopy (SEM, TEM and LM). Diffuse mesothelioma mimics bronchioloalveolar carcinoma at LM but shaggy microvilli were found on the cellular surface of the former, and short sprouts densely packed or loosely scattered, on that of the latter. Neolumen formation was found in both. Oat cell carcinoma had a smooth surface with occasional tiny projections and minute surface depressions. The cellular projections of squamous cell carcinoma were quite irregular. Differentiation between diffuse mesothelioma and bronchioloalveolar carcinoma appears feasible with SEM in tissue appropriately fixed either with formaldehyde or glutaraldehyde. The role SEM can play in diagnostic pathology is yet to be explored.