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. Precurl and postcurl H&E slides were compared using the three criteria. The number of immunohistochemistry (IHC) markers and special stains and DNA yield were recorded.
Results: DNA yield was significantly associated with the total cellularity, number and percentage of tumour cells. For 46 cases with precurl and postcurl slides, only three (6.5%) were classified as being different and in two of them the postcurl slide had greater cellularity than the precurl. IHC was performed in 83 cases, with a minimum of 1 and a maximum of 11 markers (median of 3) per case.
Conclusions: An association between the total cellularity and the tumour cellularity with the DNA yield was demonstrated using the ranges described. Evaluation of a postcurl slide is an unnecessary practice. The majority of the CB had sufficient material for ancillary studies (up to 11 markers) and mutation testing.
Keywords: CELL COUNTING; CYTOLOGY; CYTOPATHOLOGY; EGFR; LUNG CANCER.
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