Methotrexate induced histopathological changes in liver and lungs of Rabbits

Methotrexate (0.5 mg/kg, ip) produced varying degrees of congestion, degeneration and necrosis in the liver and lungs of all the treated groups (2–6) of rabbits. In the liver, focal necrotic areas, vacuolar degeneration, infiltration of mononuclear cells and dilatation of sinusoids were prominent. The changes in the nuclei were evidenced as pyknosis, karyorrhexis and karyolysis. Many hepatocytes had dark condensed nuclei. In the lungs, pulmonary congestion and cellular infiltration were observed. Focal areas of necrosis in the form of deep purple homogeneous mass were conspicuous. Proliferation of connective tissue of smooth muscle layer was noticed. The histopathological changes in the lungs were suggestive of emphysema, bronchitis and pneumonitis. The changes in normal hisoarchitecture of liver and lungs indicated that methotrexate might cause hepatotoxicity and pulmonary toxicity after its prolonged treatment.