Section detachment in immunohistochemistry: causes, troubleshooting, and problem-solving.

Section detachment in immunohistochemistry (IHC) is a common phenomenon, increasing times and costs of diagnosis and research. However, it has poorly been investigated. The aim of this study was to identify the causes of section detachment, with the purpose of defining a quality assured laboratory procedure to minimize detachment frequency. We screened 3349 IHC sections from formalin-fixed paraffin-embedded tissue, identifying 177 cases with section detachment (5.3% of the sample). Detachment regarded mainly samples of surgical breast tissue and IHC procedures in which heat pretreatment was used. Focusing on pre-analytical factors, we investigated seven main critical issues: (1) section aging; (2) section thickness; (3) slide contamination; (4) slide aging; (5) slide brand; (6) "human" influence; and (7) sample size and fixation. Each of these issues was individually investigated to establish their influence on detachment. Targeted experiments were performed by varying section age, thickness, cleanliness, slide brand and age, and sample size and fixation. Finally, to investigate operator-dependent causes, sections were cut by different operators blinded to aim. The most important factors influencing section detachment were demonstrated to be: section thickness, slide aging, slide brand, "human" influence, and size and fixation of samples. The pre-analytical phase, including all the aforementioned issues, should be standardized within a quality assurance program. By adopting these recommendations, we obtained a 34% drop in section detachment. Although section detachment remains difficult to eradicate completely, many other influences can be addressed and corrected in any laboratory leading to an increase in efficiency and cost saving.