Control specimens for immunocytochemistry in liquid-based cytology

Immunoreactivity of TTF-1, GATA-3, CEA, and p16/Ki67 cocktail in Cellprep®-processed control samples: Comparison of long-term storage in vials and slides

INTRODUCTION

Cellprep® (CP) is a novel liquid-based cytology (LBC) system. This study aimed to assess the immunoreactivity of control samples stored long-term under two storage conditions using CP.

METHODS

The immunoreactivity in control samples was evaluated under two sample storage conditions: CP vial storage at room temperature (RT: 20-25°C) and CP slide storage in a refrigerator (2-6°C). Clinical samples as controls (total: positive/negative) were immunostained using thyroid transcription factor-1 (TTF-1) (20: 14/6), GATA binding protein 3 (GATA-3) (13: 10/3), carcinoembryonic antigen (CEA) (23: 15/8), and the p16/Ki67 cocktail (20: 12/8) markers. The first immunocytochemistry (ICC) was performed within 1 month using CP vials stored at RT. Samples stored in CP vials and on CP slides were used for the second (within 3-6 months) and third (within 6-11 months) ICCs. Compared with the first ICC, the concordance of immunoreactivity for the second and third ICCs was evaluated using the weighted kappa coefficient.

RESULTS

For TTF-1, CEA, and the p16/Ki67 cocktail markers, ICC controls had stable immunoreactivity for a minimum of 6 months when samples were stored in CP vials (kappa coefficients >0.8), whereas for GATA-3, they were for 3 months. On CP slides, only for the p16/Ki67 cocktail, ICC controls had stable immunoreactivity for at least 3 months (kappa coefficient >0.8).

CONCLUSION

Clinical samples as ICC controls revealed consistently more stable immunoreactivity in CP vials than on CP slides for TTF-1, GATA-3, CEA, and the p16/Ki67 cocktail markers.

Immunoexpression of TTF1 and p63 Differentiates Lung Adenocarcinomas in Sputum Samples

Context

Differentiating NSCLC as either adeno or squamous type and identification of Epidermal Growth Factor Receptor (EGFR) mutations is clinically relevant for lung cancer patients for selecting treatment. Thyroid transcription factor-1 (TTF-1) and p63 were demonstrated as useful markers for histologic typing of lung cancer. Mutation and overexpression of EGFR has been reported in a subset of non-small cell lung cancers. If these markers can be validated for the differential diagnosis of adenocarcinoma in a sputum sample itself, it will be highly beneficial for lung cancer patients.

Aims

To evaluate whether immunocytochemical expression of TTF-1, p63, and EGFR proteins in sputum samples can be used for differential diagnosis of lung adenocarcinoma by comparing with that of the corresponding tissue samples.

Settings and Design

Ninety sputum samples and matched tissue samples were used for the study.

Subjects and Methods

Monolayered smears and cell blocks of sputum and the corresponding tissue samples were immunostained with the standard ABC method. The expression patterns of these markers were analyzed statistically and compared with clinic-pathological parameters.

Statistical Analysis Used

Chi-square test and paired t-test.

Results

The p63 protein had a positive expression in 73.9% of SCC whereas TTF1 had positive expression in 75.8% of ADC. The EGFR expression was positive in 27 cases of adenocarcinoma, 21 cases of SCC and 19 cases of NSCLC.

Conclusions

Immunocytochemistry of the aforementioned antibodies in sputum samples can be used as supplementary evidence for the subtyping of NSCLC.

Immunocytochemistry for predictive biomarker testing in lung cancer cytology

With an escalating number of predictive biomarkers emerging in non-small cell lung carcinoma (NSCLC), immunohistochemistry (IHC) is being used as a rapid and cost-effective tool for the screening and detection of many of these markers. In particular, robust IHC assays performed on formalin-fixed, paraffin-embedded (FFPE) tumor tissue are widely used as surrogate markers for ALK and ROS1 rearrangements and for detecting programmed death ligand 1 (PD-L1) expression in patients with advanced NSCLC; in addition, they have become essential for treatment decisions. Cytology samples represent the only source of tumor in a significant proportion of patients with inoperable NSCLC, and there is increasing demand for predictive biomarker testing on them. However, the wide variation in the types of cytology samples and their preparatory methods, the use of alcohol-based fixatives that interfere with immunochemistry results, the difficulty in procurement of cytology-specific controls, and the uncertainty regarding test validity have resulted in underutilization of cytology material for predictive immunocytochemistry (ICC), and most cytopathologists limit such testing to FFPE cell blocks (CBs). The purpose of this review is to: 1) analyze various preanalytical, analytical, and postanalytical factors influencing ICC results; 2) discuss measures for validation of ICC protocols; and 3) summarize published data on predictive ICC for ALK, ROS1, EGFR gene alterations and PD-L1 expression on lung cancer cytology. Based on our experience and from a review of the literature, we conclude that cytology specimens are in principal suitable for predictive ICC, but proper optimization and rigorous quality control for high-quality staining are essential, particularly for non-CB preparations.

Immunohistochemistry practices of cytopathology laboratories: a survey of participants in the College of American Pathologists Nongynecologic Cytopathology Education Program

CONTEXT

Immunohistochemistry (IHC) is important for cytology but poses special challenges because preanalytic conditions may differ from the conditions of IHC-positive controls.

OBJECTIVE

To broadly survey cytology laboratories to quantify preanalytic platforms for cytology IHC and identify problems with particular platforms or antigens. To discover how validation guidelines for HER2 testing have affected cytology.

DESIGN

A voluntary survey of cytology IHC practices was sent to 1899 cytology laboratories participating in the College of American Pathologists Nongynecologic Cytopathology Education Program in the fall of 2009.

RESULTS

A total of 818 laboratories (43%) responded to the survey by April 2010. Three hundred fourty-five of 791 respondents (44%) performed IHC on cytology specimens. Seventeen different fixation and processing platforms prior to antibody reaction were reported. A total of 59.2% of laboratories reported differences between the platforms for cytology specimens and positive controls, but most (155 of 184; 84%) did not alter antibody dilutions or antigen retrieval for cytology IHC. When asked to name 2 antibodies for which staining conditions differed between cytology and surgical samples, there were 18 responses listing 14 antibodies. A total of 30.6% of laboratories performing IHC offered HER2 testing before publication of the 2007 College of American Pathologists/American Society of Clinical Oncologists guidelines, compared with 33.6% afterward, with increased performance of testing by reference laboratories. Three laboratories validated a nonformalin HER2 platform.

CONCLUSIONS

The platforms for cytology IHC and positive controls differ for most laboratories, yet conditions are uncommonly adjusted for cytology specimens. Except for the unsuitability of air-dried smears for HER2 testing, the survey did not reveal evidence of systematic problems with any antibody or platform.

Is liquid-based cytology the magic bullet for performing molecular techniques?

OBJECTIVE

The role of pathology has evolved from the first microscopic definitions of diseases by Virchow to the new concept of molecular cytopathology. The management of diseases is now a multidisciplinary approach with the translation of morphological, imagery and molecular findings to therapeutic protocols. Obtaining the most reliable diagnostic material is the essential part of the medical management of patients.

STUDY DESIGN

Here, we try to gain a concise insight into the available data regarding the role of cytology in the application of molecular techniques, focusing on cancer cytopathology.

RESULTS

Obtaining cytological material is now feasible by different methods, and in some cases it is the only possible approach to a lesion which is not easily accessible for tissue sampling. The methods of obtaining cytological material have evolved in recent years in parallel with rapid advances in high-throughput molecular techniques, opening new windows for the diagnosis and management of diseases.

CONCLUSIONS

Different kinds of cytological material are reliable for the application of molecular techniques. Cytological material obtained in a liquid base has advantages such as the better preservation of cytomorphological features and the use of the remaining liquid for nucleic acid extraction even after long storage and the application of molecular methods.

Establishing a protocol for immunocytochemical staining and chromogenic in situ hybridization of Giemsa and Diff-Quick prestained cytological smears

Background:

Protocols for immunocytochemical staining (ICC) and in situ hybridization (ISH) of air-dried Diff-Quick or May-Grünwald Giemsa (MGG)-stained smears have been difficult to establish. An increasing need to be able to use prestained slides for ICC and ISH in specific cases led to this study, aiming at finding a robust protocol for both methods.

Materials and Methods:

The material consisted of MGG- and Diff-Quick-stained smears. After diagnosis, one to two diagnostic smears were stored in the department. Any additional smear(s) containing diagnostic material were used for this study. The majority were fine needle aspirates (FNAC) from the breast, comprising materials from fibroadenomas, fibrocystic disease, and carcinomas. A few were metastatic lesions (carcinomas and malignant melanomas). There were 64 prestained smears. Ten smears were Diff-Quick stained, and 54 were MGG stained. The antibodies used for testing ICC were Ki-67, ER, and PgR, CK MNF116 (pancytokeratin) and E-cadherin. HER-2 Dual SISH was used to test ISH. Citrate, TRS, and TE buffers at pH6 and pH9 were tested, as well as, different heating times, microwave powers and antibody concentrations. The ICC was done on the Dako Autostainer (Dako^®, Glostrup, Denmark), and HER-2 Dual SISH was done on the Ventana XT-machine (Ventana / Roche^® , Strasbourg, France).

Results:

Optimal results were obtained with the TE buffer at pH 9, for both ICC and ISH. Antibody concentrations generally had to be higher than in the immunohistochemistry (IHC). The optimal microwave heat treatment included an initial high power boiling followed by low power boiling. No post fixation was necessary for ICC, whereas, 20 minutes post fixation in formalin (4%) was necessary for ISH.

Conclusions:

Microwave heat treatment, with initial boiling at high power followed by boiling at low power and TE buffer at pH 9 were the key steps in the procedure. Antibody concentrations has to be adapted for each ICC marker. Post fixation in formalin is necessary for ISH.