Light micrograph of pulmonary adenocarcinoma (lung cancer). The tumour is composed of glandular structures, with cancer cells arranged around branching lumens (clear white spaces). Thin stromal connective tissue elements (pink to red) are in between cancer glands. Adenocarcinoma is the most common type of non-small cell lung cancer in the United States (other lung cancer types include squamous cell and small cell lung cancer). Haematoxylin and eosin stained tissue section. Magnification: x200 when printed at 10 cm.