Figure 2

Pulmonary histology at the time of lung transplantation. A: Representative microscopic field of explanted lung shows diffuse fibrosis, with both established collagen deposition (yellow-green hue) and fibroblastic proliferation (arrow, blue-green hue). There is prominent extension of smooth muscle into interstitium. Residual alveoli are lined by hyperplastic pneumocytes (200x, pentachrome stain). B: Bronchiolitis obliterans involving small airway shown by arrow (400x, pentachrome stain).