A proposal for cellularity assessment for EGFR mutational analysis with a correlation with DNA yield and evaluation of the number of sections obtained from cell blocks for immunohistochemistry in non-small cell lung carcinoma.

Aims: Different approaches have been described for reporting specimen adequacy for epidermal growth factor receptor (EGFR) mutation analysis. We aimed: (1) to conduct cellularity assessment and to investigate its association with DNA yield, (2) to compare the H&E slides taken before and after the thick sections (curls) obtained for EGFR testing and (3) to evaluate the number of ancillary studies performed.

Methods: Cell block (CB) slides of 110 non-small cell lung carcinoma cases submitted to EGFR analysis from 2010 to 2012 were reviewed for total cellularity (ranges 1-100, 100-250, 250-500, 500-750, 750-1000 and >1000 cells), tumour cellularity (ranges 1-50, 50-100, 100-300 and >300 cells) and the percentage of tumour cells.