Bibliographic Details
| Title: |
Impact of formalin fixation on mismatch repair protein evaluation by immunohistochemistry. |
| Authors: |
Grillo, Federica, Ali, Murad, Paudice, Michele, Pigozzi, Simona, Anselmi, Giorgia, Scabini, Stefano, Sciallero, Stefania, Piol, Nataniele, Mastracci, Luca |
| Source: |
Virchows Archiv: European Journal of Pathology; Nov2023, Vol. 483 Issue 5, p677-685, 9p |
| Abstract: |
Mismatch repair/microsatellite instability (MMR/MSI) status in colorectal cancer (CRC) has become fundamental as a diagnostic, prognostic, and predictive factor. MMR immunohistochemistry (IHC) is considered a simple and reliable approach; however, its effectiveness depends on pre-analytic factors. Aim of this study was to investigate the impact of different fixation times/protocols on MMR protein IHC quality. Left over tissue from surgically resected CRC samples (cold ischemia time < 30 min) where fixed as follows: standard formalin fixation (24–48 h); hypo-fixation (<20 h); hyper-fixation (>90 h); cold (4°C) fixation (24–48 h); standard fixation for small sample size (0.5×0.5 cm). Samples for each group were collected from 30 resected CRC and the following parameters were evaluated on 600 immunohistochemical stains: intensity of expression; patchiness of staining; presence of central artefact. Forty-six immunoreactions were inadequate (score 0 intensity), the majority regarding MLH1 or PMS2 in the hypo-fixation group (47.8%), followed by the hyper-fixation group (28.1%); cold formalin fixation showed the least inadequate cases. Patchiness and central artefact were more frequent in hypo-fixation and standard fixation group compared to the others. MLH1 (closely followed by PMS2) performed worse with regard to immunostaining intensity (p=0.0002) in the standard and in the hypo-fixation group (p< 0.00001). Using a small sample size improved patchiness/central artefacts. This is the first study specifically created to evaluate the impact of fixation on MMR protein IHC, showing that both formalin hypo- and hyper-fixation can cause problems; 24-h formalin fixation as well as cold (4°C) formalin fixation are recommended for successful IHC MMR evaluation. [ABSTRACT FROM AUTHOR] |
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| Database: |
Complementary Index |
