Immunocytochemistry practices in European cytopathology laboratories-Review of European Federation of Cytology Societies (EFCS) online survey results with best practice recommendations.

Background: Variability in preanalytical and analytical steps for immunocytochemistry (ICC) on cytology samples is poorly defined. The objective of this study was to evaluate current practices for ICC on cytology samples in European laboratories.

Methods: A link to an online survey with 19 questions about ICC practices was distributed to cytology laboratories through national representatives in the European Federation of Cytology Societies.

Results: In total, 245 laboratories responded to the survey by January 30, 2019. Cell blocks, cytospins, liquid-based cytology (LBC) preparations, and smears alone or in combination with other preparations were used for ICC in 38%, 22%, 21%, and 19% of laboratories, respectively. In general, various combinations of preparations were used for ICC in greater than one-half of laboratories (147 of 245; 60%), whereas only 1 specific type of cytology preparation was used in the remaining 98 of 245 laboratories (40%) laboratories. The majority of laboratories (217 of 226; 96%) performed ICC on automated platforms using protocols that were the same as those used for formalin-fixed, paraffin-embedded samples (238 of 527 laboratories; 45%), either optimized (138 of 527 laboratories; 26%) or optimized and validated (151 of 527 laboratories; 29%) for cytology preparations. Positive control slides, negative control slides, and external quality control were used in 174 of 223 (78%), 112 of 223 (50%), and 111 of 120 (50%) laboratories, respectively. Greater than 1000 ICC tests were performed yearly in 34% of laboratories (65 of 191; average, 1477 tests; median, 500 tests).

Conclusions: ICC is extensively performed in European laboratories using variously prepared cytology preparations on automated platforms, mostly without quality-assurance measures.