Assessment of the impact of the concentration of formalin on receptor studies in surgical specimens of breast carcinoma: a pilot study

Abstract

Introduction: Assessment of oestrogen, progesterone and HER2 receptor status are routinely performed on specimens fixed in 10% formalin. Objective: To assess the impact of the concentration of formalin on the oestrogen, progesterone & HER2 receptor status in surgical specimens excised for carcinoma of breast. Method: A descriptive, cross sectional study was done on excision biopsy and mastectomy specimens of breast cancer over a period of 18 months. A 1x1cm piece of tumour tissue was fixed in 50% diluted formalin and the remainder in 10% formalin. Following routine tissue processing, staining for ER, PR and HER2 receptor status was done. Allred scoring system was used to interpret ER and PR receptor status and CAP (College of American Pathologists) guidelines were used to interpret HER2 receptor status. Results: In view of the small sample size (n=20), binomial sign test was selected to assess the differences between the two groups (10% formalin vs 50% diluted formalin). There were statistically significant differences in the results with a marked downgrading of the total score of ER and PR and HER 2 receptor studies with 50% diluted formalin. Conclusion: It is vital for the specimen to be adequately fixed in 10% buffered formalin before commencing on receptor studies. DOI: http://dx.doi.org/10.4038/jdp.v9i1.7651 Journal of Diagnostic Pathology 2014; 9(1): 24-32