Viral Pneumonia in Children

Abnormal wound healing of idiopathic pulmonary fibrosis is characterized by an inappropriate wound healing response following lung injury, leading to excessive proliferation of fibroblasts and deposition of extracellular matrix proteins. Fibroblasts and myofibroblasts are central players in the fibrotic process, these cells proliferate and produce large amounts of collagen and other matrix components, contributing to the stiffening of lung tissue. Epithelial-mesenchymal transition of epithelial cells transform into mesenchymal cells, adding to the fibroblast population and promoting fibrosis. Mutations in genes related to telomere maintenance (e.g., TERT, TERC) and surfactant proteins (e.g., SFTPC, SFTPA2) have been implicated in familial and sporadic cases of idiopathic pulmonary fibrosis. Environmental triggers as cigarette smoking, a well-established risk factor that can exacerbate lung damage and fibrosis; occupational exposures like contact with certain dusts, such as metal and wood dust, and agricultural chemicals may increase the risk. Chronic viral infections have been suggested as potential triggers for the fibrotic process. Usual interstitial pneumonia (UIP) is the hallmark histopathological pattern of idiopathic pulmonary fibrosis characterized by patchy fibrosis with areas of fibrosis interspersed with relatively normal lung tissue; honeycombing with formation of cystic spaces, typically subpleural and paraseptal, lined by bronchiolar epithelium; fibroblastic foci displaying clusters of proliferating fibroblasts and myofibroblasts at the edges of fibrotic areas, indicating active disease; temporal and spatial heterogeneity revealing presence of lesions at different stages of development within the same lung, reflecting ongoing fibrotic activity.