Processing Resection Specimens

Gross examination and tissue sampling of resection specimens are essentially dictated by the rules of cancer staging and the need to assess the completeness of resection.

The TNM staging system is not applicable to small-cell lung cancer (SCLC) because of the particularly aggressive behaviour of this tumor type. For SCLC, a two-stage system is favoured, the stages being referred to as "limited" (confined to hemithorax plus/minus mediastinum with ipsilateral supraclavicular lymph node involvement) and "extensive" disease^(7,8).

The following recommendations are relevant to tumor typing:

1. Resected lung specimens should be expanded by perfusion with 4% formaldehyde through the bronchus and then fixed for 12 to 24 hours before dissection.

2. Heterogeneity in differentiation within any one tumor is characteristic of lung cancer and, therefore, adequate representation is essential for correct cell typing. In a study of 100 lung tumors in which the presenting slides were randomized and examined separately, Roggli et al⁽⁹⁾ found that only 34% of the tumors were homogeneous for cell type. It is therefore recommended that at least one paraffin-embedded tissue block be submitted per centimetre of the maximum dimension of the tumor in the resection specimen.