by Shouvik Biswas #1451

A term originally used to describe the non- neoplastic lung reaction to inhalation of mineral dusts. The term has been broadened to include organic as well as inorganic particulates, chemical fume, and vapor induced non- neoplastic lung diseases.

Fibrotic - Involving focal nodular or diffuse fibrosis. - Types: Silicosis, coal worker’s pneumoconiosis (anthracosis), asbestosis, berylliosis, and talcosis. Non-fibrotic - Involving particle laden macrophages with minimal or no fibrosis. - Siderosis, stannosis, baritosis.

Some of the particles become impacted at alveolar duct bifurcation, where macrophages accumulate and engulf the trapped particulates. The pulmonary alveolar macrophage is a key cellular element in the initiation and perpetuation of lung injury and fibrosis. Particles can activate the inflammasome (induce IL-1 production) or trigger the macrophages to release products that mediate an inflammatory response and initiate fibroblast proliferation and collagen deposition.

Ingested silica particles cause activation and release of mediators by pulmonary macrophages, including IL-1, TNF, fibronectin, lipid mediators, oxygen-derived free radicals, and fibrogenic cytokines. Histopathology: - Concentrically arranged hyalinized mature collagen fibers. - Peripheral zone of particle laden macrophages. - Birefringent silicate crystals (1-3 um)

Inhaled coal will form “coal macules” which are anthrocotic pigmentation without fibrotic tissue. Pigment laden macrophages surround the bronchioles in the lobular core. Primarily centrilobular distribution. Calcification develops a central nodular dot.

Two distinct forms: - Serpentine: the fiber is curly and flexible with carcinogenic potential. - Amphibole: the fiber is straight and stiff; it has a greater fibrogenic potential. Asbestos bodies: golden brown, fusiform, or beaded rods with a translucent center. Pleural plaques are common manifestations of asbestos exposure.

Parenchymal interstitial fibrosis Localized fibrous plaques or diffuse fibrosis in pleura Pleural effusion Lung carcinoma Malignant pleural and peritoneal manifestations Laryngeal carcinoma

Chong, Semin, and Kyung Soo Lee. "Pneumoconiosis: Comparison of Imaging and Pathologic Findings." RadioGraphics:. 23 May Web. 11 Feb Kumar, Vinay. "Lung." Robbins Basic Pathology. 9th ed. Philadelphia, PA: Elsevier/Saunders, Print.