Chronic Inflammation

A 52-year-old man from rural India presents with a chronic productive cough, low-grade fever, and weight loss over 6 months. Chest X-ray shows a cavitary lesion in the right upper lobe. Sputum smear microscopy is positive for acid-fast bacilli. Histopathology of the lung tissue shows caseating granulomas with epithelioid histiocytes and Langhans giant cells. Which is the most common cause of chronic inflammation in this patient?

A 52-year-old man presents with a 6-month history of progressive dysphagia and retrosternal discomfort. Endoscopy reveals a stricture in the mid-oesophagus with surrounding erythema. Biopsy shows chronic inflammatory infiltrate with fibrosis. Which investigation is most appropriate to confirm the diagnosis of oesophageal Crohn's disease?

A 58-year-old man with a 10-year history of chronic osteomyelitis of the femur presents with purulent drainage from a sinus tract. Biopsy shows suppurative exudate with neutrophils and fibrosis. Which finding would indicate progression to chronic granulomatous inflammation rather than persistent suppurative inflammation?

Which of the following is the hallmark histological feature of chronic inflammation?

Which cytokine is the primary driver of macrophage activation and is considered the most important mediator in chronic inflammation?