Quantitative assessment of asbestos fibers in some normal and pathological extra-abdominal tissues—a scoping review

Abstract: Background: Asbestos is a mineral present in nature and it has been used for years in numerous settings. Asbestos enters the bloodstream and lymphatic system mainly through breathing. Objectives: Studies with asbestos fiber’s quantification in human tissues are scarce except for the lung. This article summarizes asbestos studies in some extra-abdominal tissues. Methods: A scoping review of articles that quantified asbestos fibers in extra-abdominal tissues (lymph nodes, pharynx, larynx, trachea, heart) by electron microscopy (Scanning—SEM or Transmission—TEM) was performed. Results: The 10 studies selected comprised 52 cases, out of whom 108 samples were analyzed. Mostly samples were lymph node tissues (102), followed by larynx (3) and myocardium (3). No studies were found that determined the presence of asbestos in the pharynx or trachea. The concentration of asbestos fibers detected in the lymph nodes was from 0.003 million fibers per gram of dry tissue (mfgdt) up to 7400 mfgdt, in the larynx the range was from 0.5 mfgdt up to 3.6 mfgdt, in myocardium no asbestos fibers were detected. Discussion: The studies included were heterogeneous in terms of case and sample characteristics and analytical techniques. As subjects exposed to asbestos are often positive for fibers in thoracic lymph nodes, we suggest that whenever a human tissue sample is analyzed for asbestos presence, the relevant draining lymph node should be concomitantly studied.