A 42-year-old woman from Delhi with a history of poorly controlled diabetes mellitus presents with a 4-month history of cough, hemoptysis, and constitutional symptoms. Chest X-ray shows bilateral upper-lobe infiltrates with cavitation on the right side. Sputum smear microscopy is positive for acid-fast bacilli on Ziehl-Neelsen staining. She is started on anti-tuberculous therapy (RIPE regimen). After 2 weeks of treatment, her symptoms improve, but a repeat chest X-ray shows minimal radiological improvement. A lung biopsy is performed, which shows extensive caseous necrosis with sparse inflammatory cells and very few epithelioid macrophages. Which of the following pathological findings best explains the delayed radiological resolution despite clinical improvement?