Figure 4. (a) Tumour infiltrates the pleura and thickened fibrous tissue that encapsulated the necrotic lung parenchyma (haematoxylin and eosin, x50). (b) Tumour cells appear polygonal and epithelioid, and they infiltrate the blood vessel lumens (haematoxylin and eosin, magnification x100). (c) Immunohistochemistry show strong positive staining of tumour cells for vimentin (magnification x200). (d) Many tumour cells also show membranous staining for CD31, a marker of endothelial cells (magnification x200).