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Rare pneumoconiosis induced by long‐term amorphous silica exposure: The histological characteristics and expression of cyclooxygenase‐2 as an antifibrogenic mediator in macrophages
Author(s) -
Kumasaka Toshio,
Akaike Yasushi,
Nakamura Osamu,
Yamazaki Kazuma,
Moriyama Hiroshi,
Takemura Tamiko
Publication year - 2011
Publication title -
pathology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.73
H-Index - 74
eISSN - 1440-1827
pISSN - 1320-5463
DOI - 10.1111/j.1440-1827.2011.02715.x
Subject(s) - pathology , silicosis , pneumoconiosis , macrophage , chemistry , lung , giant cell , fibrosis , electron microprobe , medicine , mineralogy , biochemistry , in vitro
Pneumoconiosis induced by non‐crystalline silica is considered rare, although silicosis resulting from contact with crystalline silica is a well‐known hazard associated with progressive pulmonary fibrosis. Here we describe a patient with pneumoconiosis induced by diatomaceous earth composed of amorphous silica detected by two‐dimensional imaging of chemical elements. The histology revealed that the disease was characterized by a granulomatous reaction in the lung. A large number of macrophages laden with yellow and black pigments accumulated in alveolar spaces and were incorporated into the interstitial sites. Bronchiolar walls were destroyed by palisade macrophages, suggesting airflow obstruction. Packed macrophages adhering to and covering the denuded interstitium indicated that macrophages might be incorporated into pulmonary interstitium in this fashion. Immunohistochemistry showed that cyclooxygenase‐2, an antifibrogenic mediator, was intensely expressed in the macrophages compared with macrophages in control lungs. No birefringent material was found in the tissues. When two‐dimensional analysis of chemical elements was performed using an electron probe microanalyzer with a wavelength‐dispersive spectrometer, the resultant fine mapping of silicon and oxygen on the tissue indicated that the pigments phagocytosed by macrophages corresponded to amorphous silica. In conclusion, two‐dimensional analysis of elements is very useful for pathologists in correlating the presence of chemical elements with histological changes.