A 25 year old man presented with fever, cough, expectoration and breathlessness of 2 months duration. Contrast enchanced computed tomography of the chest showed bilateral upper lobe fibrotic lesions and mediastinum had enlarged necrotic nodes with peripheral rim enhancement. Which one of the following is the most probable diagnosis?

This patient is showing features of tuberculosis. His chest CT findings are suggestive of post primary or adult type tuberculosis. Post primary tuberculosis occur from endogenous reactivation of distant latent infection or from a recent infection. It is usually seen in the apical and posterior segments of the upper lobes, which has higher mean oxygen tension. Chest X ray may shows infiltrates or cavities in the upper lobe of lung. When there is massive involvement of pulmonary segments or lobes, lesions coalesce together produces caseating pneumonia. Ref: Current Medical Diagnosis and Treatment 2012, Chapter 9 ; Harrison's Internal Medicine, 18th Edition, Chapters 165, 329