A 45 yr old patient presents with fever, night sweats, weight loss. On X ray a mass in apical lobe of lung is seen. On histopathology found to have caseous necrosis. What is the underlying process?

Ans. (b) Hypersensitivity reaction with modified macrophages, lymphocytes and giant cells(Ref: Robbins 9th/pg 208-211; 8th/pg 204-208)The given clinical features and radiological Findings are suggestive of Tuberculosis in which histopathology of the affected organ shows granuloma, that consists of modified macrophages, lymphocytes and giant cells.