Sample preparation
The block is cut into sections using a microtome.
The tumour biopsy is fixed in formalin and embedded in a block of paraffin for storage.
Examination
The tumour sections are examined by a pathologist to ensure that tumour cells are present.
If possible, the pathologist marks the area of the slide that contains tumour cells.
Macrodissection
If possible, the tumour sample should be macrodissected so that only tumour cells are used for the analysis. This decreases risk of false negative results.
Macrodissection is scraping off tumour cells from the slide with a scalpel and putting them into a tube (Eberhard 2008).
Recording pathology information
The following information may be recorded:
• sample form (block or slides)
• sample type (biopsy or resection)
• tissue type (lung, lymph node, pleura, metastatic site)
• adequate tissue (>50 cells)
• histological classification (eg adenocarcinoma)
• tumour grade (well, moderately or poorly differentiated)
• other (including cell type – inflammatory, necrotic, mitotic, apoptotic etc)