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Ferruginous bodies observed in lungs of patients affected by mesothelioma, asbestosis, and pulmonary carcinoma are important to relate the illness to exposure, environmental or occupational, to asbestos. Identification of the inorganic phase constituting the core of the ferruginous bodies, formed around asbestos but also around phases different from asbestos, is essential for legal purposes. Environmental scanning electron microscopy/energy dispersive spectroscopy was used to identify the fibrous mineral phase in the core of ferruginous bodies observed directly in thin sections of tissue, without digestion of the biological matrix. Spectra were taken with sequential analyses along a line crossing the core of the ferruginous bodies. By comparing the spectra taken near to and far from the core, the chemical elements that make up the core could be identified.

In a previous work it has been demonstrated that micro-Raman spectroscopy is a technique able to recognize crystalline phases on untreated samples. In that case, inorganic particles and uncoated fibers from bronchoalveolar lavage (BAL) of a patient affected by pneumoconiosis were identified and characterized. In this work the technique is applied to asbestos bodies, that is, to coated fibers, and on crystallizations and fibrous phases observed in the plural plaque from patients affected by mesothelioma. From the Raman analysis the abundant fibrous material observed in the pleural area is talc, whereas rounded grains in the pleural tissue show the Raman spectrum of apatite, a calcium phosphate mineral particular to bones. In the pulmonary tissue many asbestos bodies, consisting of the incorporated fibers coated by iron-rich proteins, were observed. Under the 632.8 nm laser beam of the spectrometer, photo-crystallization of hematite in the iron-rich material forming the asbestos bodies can be proposed by the changes in the Raman spectra acquired during subsequent acquisitions. Nevertheless, the identification of the mineral phase constituting the incorporated fiber was possible by analyzing the Raman spectra; the results were confirmed by variable pressure scanning electron microscopy with annexed energy dispersive spectroscopy (VP-SEM-EDS) analyses.