It is with great enthusiasm that we present this special issue of Acta Cytologica, which is dedicated to exploring the transformative role of immunocytochemistry (ICC) in cytology. With the recent advances in personalised medicine, ICC has emerged as a cornerstone technique, bridging the gap between morphology and molecular diagnostics in cytopathology. Its integration has revolutionised our ability to refine diagnoses, guide treatment decisions, and uncover insights into disease mechanisms.
Cytological specimens, due to their minimally invasive nature, are often the first window into understanding pathology. Their diagnostic utility has historically been challenged by the limited volume of material and inherent cellular heterogeneity. In this context, ICC provides a powerful tool to enhance diagnostic precision, allowing us to interrogate key biomarkers, differentiate between morphologically similar entities, and even predict therapeutic responses. Immunohistochemistry has been established and standardised on formalin-fixed-paraffin-embedded histological tissue. However, the current landscape for ICC is still in evolution, as discussed in the article “Quality Assurance in Immunocytochemistry” by Lozano et al. [1]. Srebotnik [2] discussed further the complexities involved in complete standardisation and guidelines implementations while describing the key pillars in “best practices” – control slides, optimised protocols, and external quality control.
As we delve into the theranostic implications of various markers and the potential impact of such recent advances on the cytological specimens, we close a gap in patient care with early detection significantly impacting management and potentially improving survival. This issue highlights the diverse applications of ICC in cytology, showcasing advancements in its use across a wide range of diagnostic settings, from the identification of malignancies in fine-needle aspiration cytology to the characterisation of rare entities in effusion cytology. Michael and Rodgers discussed the role of ICC in Mesothelioma, a rare tumour previously diagnosed almost exclusively on histology samples. A definitive diagnosis of Mesothelioma on cytological samples spares the patients additional diagnostic procedures and affords them an opportunity for early surgical intervention and therapy [3]. Tralongo et al. [4] discuss the role of ICC in discriminating between benign and malignant lesions of head and neck cytology while being an important adjuvant tool in targeted therapies. The crucial role of ICC in the accurate diagnosis and testing of predictive biomarkers in thoracic cancers is also discussed in this issue [5]. Hirokawa and Suzuki [6] explore newer innovative methods of performing ICC on various cytology samples, such as the LBC method, cell blocks, and cell transfer methods. They go on to describe the role of ICC in diagnosing thyroid tumours, assessing the differentiation and grading of carcinomas, estimating the primary organ in metastatic carcinomas, and detecting gene abnormalities.
These articles further review the role of ICC in diagnosing emerging entities on cytology samples. The importance of positive control is paramount, a fact highlighted by Srebotnik et al. [7]. They demonstrate a novel approach for preparing integrated on-slide positive controls for ICC on methanol-fixed cytospins using standardised cyto-centrifugation. This low-cost and easily applicable method provides the highest level of quality control in performing ICC protocols.
The articles in this issue reflect the collaborative efforts of researchers, clinicians, and technical experts who are at the forefront of cytopathology innovation. One such innovative technique is the dual ICC of p16INK4a/Ki67 as a triage marker to identify patients with CIN2 lesions among HPV-positive women (online ahead of print) [8]. We hope this compilation enhances your understanding of ICCs potential and inspires innovative applications in your practice and research.
As we navigate an era of personalised medicine, the importance of integrating ancillary techniques into cytology cannot be overstated. Together, these advancements empower us to deliver more precise, timely, and impactful diagnoses for our patients. We invite you to explore the insights shared in this issue and join us in recognising the significant progress made in the field of cytology through the lens of ICC.
Conflict of Interest Statement
The authors have no conflicts of interest to declare.
Funding Sources
This study was not supported by any sponsor or funder.
Author Contributions
D.J. and L.B.: conceptualisation and writing – drafting, editing, and reviewing.
