Silicosis - Thoracic Imaging
Title: Thoracic Imaging - Silicosis
Author: Martins Martina
Comment: Howarth Nigel
Department: Département de Radiologie
KeyWords: Silicosis; adenopathies
Chapter: Occupational pneumopathy
Clinical Presentation: 80-year old patient admitted to hospital withcough and
dyspnea. He had worked as a miner in the construction ofdams.
Comment: Inhaled particles reach the alveoli where they arephagocytosed by
macrophages. Silica is specifically toxic tolysosomal membranes. The release of
intracellular enzymes causesthe lysis of the macrophage. The macrophages undergoing
lysisaccumulate against the alveolar walls before seeping into theinterstitial space where
they trigger a fibroblastic reactionresulting in a silicotic nodule. Chest X-ray findings which
arehighly suggestive of silicosis include: interstitial, micro- ormacronodular, well delineated,
homogeneous opacities and/orreticulated opacities, predominant posteriorly in the apices
and inthe mid-zones of the lungs; homogeneous, confluent, tumour-likeopacities in upper
and posterior territories, representing massesof fibrosis which may contain central or
peripheral calcificationand are sometimes necrotic. Hilar adenopathy is present, with
fineperipheral calcification, producing an egg-shellpattern.
Description: The frontal and lateral chest X-rays show largeconfluent opacities
with irregular contours in the mid zones ofboth lungs, representing masses of progressive
pulmonary fibrosis.CT images show multiple enlarged mediastinal lymph nodes, perihilarand
basal nodules and masses, with surrounding fibrosis and abilateral pleural effusion.
References: Remy-Jardin M, Remy J, Farre I, Marquette CH.
Computedtomographic evaluation of silicosis and coal workers'pneumoconiosis. Radiol
Clin North Am. 1992;30:1155-76. Shipley RT.The 1980 ILO classification of radiographs of
the pneumoconioses.Radiol Clin North Am. 1992;30:1135-45.
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