Overview of microprobe analysis in pulmonary pathology

In this series of articles in the current issue of Ultrastructural Pathology, Dr. Victor L. Roggli and his colleagues at Duke University continue their impressive studies on asbestosis and other pneumoconioses. Here and elsewhere, Dr. Roggli has clearly documented the importance of quantitative analysis of inhaled particulates, especially asbestos fibers, and has well illustrated the power of fiber analysis using electron microscopy to definitively identify specific asbestos fiber types.

In his President’s Lecture, given before the Society for Ultrastructural Pathology Ultrapath XVII meeting in Asheville, NC, in July, 2014, Dr. Roggli reviews six vignettes in which fiber analysis by electron microscopy corrected serious misconceptions regarding asbestos and disease. To mention just one example, by identifying amosite in the lungs of railroad workers, Dr. Roggli refutes the claim that railroad workers were exposed exclusively to chrysotile [1].

Dr. Roggli’s analytical approach was also critical in documenting that certain mesothelioma patients lack asbestos exposure. These patients tend to be younger women [2]. However, studies by his colleagues on peritoneal mesothelioma indicate that no clear cutoff exists for determining an asbestos etiology in peritoneal mesothelioma; consequently, the same fiber analysis criteria are used for causation in both pleural and peritoneal mesotheliomas [3].

Two single case reports provide additional evidence of the power of this approach to fiber analysis. One patient with a lung carcinoma, but without asbestosis, nevertheless had greatly increased asbestos fibers per gram of wet lung tissue, thus arguing that asbestos was a substantial contributing factor to this patient’s lung cancer [4]. Galeotti et al. illustrate how energy-dispersive x-ray analysis mapping can be used to study a case of endogenous pneumoconiosis [5].

Two other case reports document the power of analytical electron microscopy to establish difficult diagnoses, such as aluminum-induced pneumoconiosis [6] and tungsten carbide pneumoconiosis [7].

Altogether, these seven articles offer the reader convincing evidence of the power of analytical electron microscopy when utilized in concert with an excellent medical/occupational history, with standard histopathology, and with quantitation of asbestos fiber content and of other particulates. As other new analytical microscopic tools become available, our understanding of these disease processes will continue to deepen.