Etiology and pathogenesis
Silica particles less than 5 μm in diameter enter lungs and are phagocytozed by macrophages.
Free particles and fibroblast stimulating factor are released from the dead macrophages.
Basic PATHOLOGY
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Pneumoconiosis: Silicosis Chronic cor pulmonale Pulmonary carcinoma
Pneumoconiosis
a term originally coined to describe the lung reaction to inhalation of mineral dusts and now has been broadened to include diseases induced by:
Crystalline is the most toxic and fibrogenic, especially quartz.
Ingested silica particles
activation of pulmonary macrophage
release of mediators by pulmonary macrophage: IL1, TNF, Fibronectin Lipid mediators Oxygen-derived free radicals Fibrogenic cytokines
Stage Ⅲ:
Lesion may occur at entire lung with progressive massive fibrosis with cavities. There is grating when cut . The merged silicotic nodules are enlarged in size and demonstrate a neoplasm-like mass.
Morphology
1. Formation of silicotic nodules. 2. Diffuse fibrosis of pulmonary stroma.
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The nodules are black or gray-white in color and physically hard, tiny barely palpable, discrete ones in upper zones of the lungs.
Silicosis
Conception:
Silicosis is one of pneumoconiosis caused by deposition of silica particles in lungs. The characteristic lesion is silicotic nodule consisted of concentrated collagen fibers.
grating when cut.
In an advanced case, the lungs may be almost completely solid.
The hilar lymph nodes are much enlarged and pleura also involved even in the early stages, and their cut surface resembles the nodules.
The merged silicotic nodules are demonstrated
Histologically, the silicotic nodule often experienced three stages:
cellular nodule
fibrotic nodule
hyaline nodule.
Staging
Stage Ⅰ:
Lesion limited at the hilar lymph nodes and subpleural zones with the silicotic nodules is few in number.
Stage Ⅱ:
Lesion may scattered at upper and lower area in lung concentrated in the hilus with the silicotic nodules increase in number.
organic particulates inorganic particulates chemical fume- and vapor-
The mineral dust pneumoconiosis: the three most common types— Coal Work’s Pneumoconiosis Silicosis Asbestosis and Asbestosis-related Disease
Microscopically, the silicotic nodule demonstrates concentrically arranged hyalinized collagen fibers surrounding an amorphous center. A “whorled” appearance of the collagen fibers typically.
Complications
1. Tuberculosis 2. Cor pulmonale 3. Emphysema
Chronic cor pulmonale
(Pulmonary hypertensive heart disease)
Definition: