Practical issues related to immunocytochemistry on cytological smears: Tips and recommendations

Abstract

Objective: Immunocytochemistry (ICC) is essential for enhancing diagnostic accuracy and identifying markers for diagnosis, prognosis and targeted therapies. While cell blocks (CBs) are preferred for standardization and optimized staining, cytological smears are an alternative when CBs are unavailable. However, the literature on ICC protocols for smears is sparse. This review addresses preparation, fixation and protocols for nuclear and cytoplasmic antibodies on smears, drawing from our laboratory's experience. Methods: We reviewed procedures for ICC on cytological smears using existing literature and practical insights from our laboratory. Results: Commercially available antibodies were found to be reliable for ICC on smears if specimens are properly prepared and fixed. Protocols developed in our laboratory maintained antigenicity and provided clear staining results. Conclusions: Although ICC on CBs is the gold standard for standardization, cytological smears are a viable alternative when CBs are unavailable. Success in ICC on smears depends on proper preparation and fixation. This review offers practical protocols and insights to help laboratories optimize ICC on cytological smears. Further research and standardization are necessary to enhance reproducibility and reliability of ICC on smears. The practical information provided is based on personal experience in our laboratory.