Application of Immunohistochemistry to Cytology

Abstract

Context.—The uses of monoclonal antibodies via immunochemistry have been reported frequently within the literature using various methodologies with applications to cytology specimens. The direct application of immunochemistry to cytology may have a variety of pitfalls that the general pathologist familiar with its application to histology may be unaware of when applying it prospectively to patient specimens. Objective.—To review common pitfalls when applying immunochemistry to cytology specimens and to suggest approaches to the more common differential dilemmas that apply to a variety of cytology specimens that could be seen in a general pathology practice. Data Sources.—The authors' own experiences of applying immunochemistry to cytopathology specimens within an academic setting along with supportive data from the literature. Conclusions.—Immunochemistry can be used to increase the predictability of a cytology diagnosis if care is taken with the cytology sample preparation methodology and there is judicious use of select monoclonal antibody panels to support a specific cytology diagnosis. Up-to-date evidence-based antibody databases should be used when selecting antibody panels.

When Tissue Antigens and Antibodies Get Along

“…45 , 339 A more detailed discussion of the pros and cons of cytologic preparation methods is in Fowler and Lachar. 107…”

“…Other challenges in ICC are (1) use of adequate positive and negative controls (ideally, controls should be treated in the same way as test samples), (2) nonstandardized methodology and antibody titers, (3) difficulty in evaluation of immunoreactivity in inflamed or necrotic samples, (4) difficulty in distinguishing normal from neoplastic cells, and (5) deleterious effect of protease digestion in non–formalin-fixed material. 107,188…”

Antigen Retrieval Immunohistochemistry

“…On the basis of these conditions, L. J. Fowler and Lachar (2008) highlighted the challenges that exist in application of ICC to cytopathology. One of the major issues is lack of proper control samples.…”

“…Cell blocks simulate surgical pathology samples. They can be handled and stored in a similar manner (Shin et al 2007;Fowler LJ and Lachar 2008) and stained using AR and IHC protocols and antibody panels analogous to those used in surgical pathology, providing a stain quality that is superior to most ICC results on cytospins or smears (Fetsch and Abati 2001;Fetsch et al 2002). Therefore, this technique is highly recommended as the first choice for ICC analysis whenever enough cell samples are available (Fetsch and Abati 2001;Miller and Kubier 2002;DeLellis and Hoda 2006;Liu H et al 2007;Shin et al 2007).…”

Signet ring cell carcinocythaemia in an advanced gastric carcinoma

“…Immunocytochemistry is a consolidate method of diagnosis that can be reliably performed in any cytological specimen, including blood smear cells, following the validated protocols. 5 For this reason, immunocytochemical stains for Ber-EP4 and cytokeratin CKAE1/AE3 antibodies were performed (Figure 1C,D), confirming the diagnosis of carcinocythaemia.…”