Bleomycin toxcity is characterized by destructionof aEUR'

Type I Pneumocytes {Ref: Fishman's pulmonary disease and disorders 4/e p 1069; Devito Oncology 8/e p 2673] Neomycin is well known to cause pulmonary toxicity. -The incidence of Neomycin induced pulmonary toxicity is 5% for a total cumulative dose of 450 units and 15%.for higher dosages. - Bleomycin is concentrated preferentially in the lung and is inactivated by hydrolase enzyme. This enzyme is relatively deficient in lung tissue. - This may explain relative sensitivity of Neomycin to lung tissue Pathological features of Neomycin toxicity i) Early endothelial cell damage ii) Destruction of type I pneumocytesdeg iii) Migration of type 11 pneumocytes into alveolar spaces inducing interstitial changes Type 1 epithelial _cells are more vulnerable to Neomycin toxicity and are destroyed by bleonlycin2 -Following destruction of tope 1 pneumocytes repair is characterized by hyperplasia and dysplasia of type 11 pneumocytes - Fibroblast proliferation with subsequent pulmonary fibrosis is probably the basis for irreversible changes induced by Neomycin. Also know Histopathology of lung in Neomycin toxicity Endothelial cell edema and Webbing Necrosis of type 1 pneumocytes Hyperplasia and metaplasia of type Il pneumocytes Inflammatory infiltrate with PMN Proliferation of fibroblast and fibrosis