Molecular diagnostic cytopathology: definitions, scope and clinical utility

Training in molecular cytopathology testing

Training in molecular cytopathology testing is essential in developing and maintaining skills in modern molecular technologies as they are introduced to a universal health care system such as extant in the UK and elsewhere. We review the system in place in Northern Ireland (NI) for molecular testing of solid tumours, as an example to train staff of all grades, including pathologists, clinical scientists, biomedical scientists and equivalent technical grades. We describe training of pathologists as part of the NI Deanery medical curriculum, the NI training programme for scientists and laboratory rotation for Biomedical Scientists. Collectively, the aims of our training are two-fold: to provide a means by which individuals may extend their experience and skills; and to provide and maintain a skilled workforce for service delivery. Through training and competency, we introduce new technologies and tests in response to personalised medicine therapies with a competent workforce. We advocate modifying programmes to suit individual needs for skill development, with formalised courses in pre-analytical, analytical and postanalytical demands of modern molecular pathology. This is of particular relevance for cytopathology in small samples such those from formalin-fixed paraffin-embedded cell blocks. We finally introduce how university courses can augment training and develop a skilled workforce to benefit the delivery of services to our patients.

Efficiency of EGFR mutation analysis for small microdissected cytological specimens using multitech DNA extraction solution

BACKGROUND

The microdissection method has greatly facilitated the isolation of pure cell populations for accurate analysis of mutations. However, the absence of coverslips in these preparations leads to poor resolution of cellular morphological features. In the current study, the authors developed the MultiTech DNA extraction solution to improve the visualization of cell morphology for microdissection and tested it for the preservation of morphological properties of cells, quality of DNA, and ability to detect mutations.

METHODS

A total of 121 cytological samples, including fine-needle aspirates, sputum, pleural fluid, and bronchial washings, were selected from hospital archives. DNA extracted from microdissected cells was evaluated by epidermal growth factor receptor (EGFR) mutation analysis using pyrosequencing, Sanger sequencing, and peptide nucleic acid (PNA)-mediated real-time polymerase chain reaction clamping. Morphological features of cells as well as DNA quality and quantity were analyzed in several cytological samples to assess the performance of the MultiTech DNA extraction solution. The results were compared with previous EGFR mutation tests.

RESULTS

The MultiTech DNA extraction solution improved the morphology of archived stained cells before microdissection and provided a higher DNA yield than the commercial QIAamp DNA Mini Kit in samples containing a minimal number of cells (25-50 cells). The authors were able to detect identical EGFR mutations by using different analysis platforms and consistently identified these mutations in samples comprising as few as 25 microdissected cells.

CONCLUSIONS

The MultiTech DNA extraction solution is a reliable medium that improves the resolution of cell morphology during microdissection. It was particularly useful in EGFR mutations of samples containing a small number of cells.

Integrating molecular diagnostics into histopathology training: the Belfast model

Molecular medicine is transforming modern clinical practice, from diagnostics to therapeutics. Discoveries in research are being incorporated into the clinical setting with increasing rapidity. This transformation is also deeply changing the way we practise pathology. The great advances in cell and molecular biology which have accelerated our understanding of the pathogenesis of solid tumours have been embraced with variable degrees of enthusiasm by diverse medical professional specialties. While histopathologists have not been prompt to adopt molecular diagnostics to date, the need to incorporate molecular pathology into the training of future histopathologists is imperative. Our goal is to create, within an existing 5-year histopathology training curriculum, the structure for formal substantial teaching of molecular diagnostics. This specialist training has two main goals: (1) to equip future practising histopathologists with basic knowledge of molecular diagnostics and (2) to create the option for those interested in a subspecialty experience in tissue molecular diagnostics to pursue this training. It is our belief that this training will help to maintain in future the role of the pathologist at the centre of patient care as the integrator of clinical, morphological and molecular information.

Development of an ammonium sulfate DNA extraction method for obtaining amplifiable DNA in a small number of cells and its application to clinical specimens

DNA extraction from microdissected cells has become essential for handling clinical specimens with advances in molecular pathology. Conventional methods have limitations for extracting amplifiable DNA from specimens containing a small number of cells. We developed an ammonium sulfate DNA extraction method (A) and compared it with two other methods (B and C). DNA quality and quantity, β-globin amplification, and detectability of two cancer associated gene mutations were evaluated. Method A showed the best DNA yield, particularly when the cell number was very low. Amplification of the β-globin gene using DNA from the SNU 790 cell line and papillary thyroid carcinoma (PTC) cells extracted with Method A demonstrated the strongest band. BRAF(V600E) mutation analysis using ethanol-fixed PTC cells from a patient demonstrated both a "T" peak increase and an adjacent "A" peak decrease when 25 and 50 cells were extracted, whereas mutant peaks were too low to be analyzed using the other two methods. EGFR mutation analysis using formalin-fixed paraffin-embedded lung cancer tissues demonstrated a mutant peak with Method A, whereas the mutant peak was undetectable with Methods B or C. Method A yielded the best DNA quantity and quality with outstanding efficiency, particularly when paucicellular specimens were used.

Comparative validation of c-kit exon 11 mutation analysis on cytology samples and corresponding surgical resections of gastrointestinal stromal tumours

OBJECTIVE

Studies have shown that c-kit mutation analysis of gastrointestinal stromal tumours (GISTs) obtained by endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) can be routinely performed. We validated c-kit exon 11 mutational analysis on cell block material obtained from fine needle aspiration cytology (FNAC) for diagnostic purposes and compared it with the same analysis in formalin-fixed paraffin-embedded full sections of the corresponding resection specimens.

METHODS

c-kit mutation analysis was done on cell block material obtained from ten cases encountered in our department from 1999 to 2008 on which FNAC was attempted pre-operatively. The findings were compared with analysis on full paraffin section of the corresponding resected tumours in seven cases where patients opted for resection. c-kit exon 11 was examined via bidirectional nucleic acid sequencing.

RESULTS

Our results showed 100% concordance for the presence and type of exon 11 mutation in the resected and aspirated tumours in all seven cases. These mutations had diagnostic value when compared with other neoplasms that are part of the cytomorphological differential diagnosis, such as leiomyosarcoma or gastric adenocarcinomas.

CONCLUSION

Molecular cytopathology is a powerful tool that can complement morphology and immunohistochemical assessment of cytological material in routine practice for the diagnosis and prognostication of GISTs. We briefly discuss the advantages and limitations of the fine needle method of obtaining tissue for the diagnosis and prognostication of GISTs, and its current therapeutic strategies.

Happenings in Histopathology – A Post-World War II Perspective

There have been several important developments in the practice of histopathology since World War II; those reviewed in this lecture are grouped under 4 headings: new techniques (cytopathology, electron microscopy, immunohistochemistry and molecular pathology), organisational issues (recruitment, training and certification, subspecialties, quality control and consultations), ethical and legal issues (service costs, and the ownership and uses of biopsy tissues) and globalisation (international associations, standardised classification and nomenclature, and telepathology). Advances in the fields of molecular pathology and telepathology are expected to have the greatest impact on the practice of pathology in the next decade. Key words: Anatomic pathology, Organisation, Globalisation, Telepathology

Time for evidence-based cytology

Evidence-based medicine (EBM) is a fashionable and an extremely hot topic for clinicians, patients and the health service planners. Evidence-based cytology (EBC) is an offshoot of EBM. The EBC is concerned with generating a reproducible, high quality and clinically relevant test result in the field of cytology. This is a rapidly evolving area with high practical importance. EBC is based entirely on research data. The various professional bodies on cytology design and recommend guidelines on the basis of evidences. Once the guideline is implemented and practiced then the experiences of the practicing cytopathologists may be used as a feed back to alter the existing guideline. The various facets of EBC are sampling and specimen adequacy, morphological identification and computer based expert system, integrated reporting, identification of the controversial areas and high quality researches for evidences. It is the duty of the individuals and institutions to practice EBC for better diagnosis and management of the patients. In this present paper, the various aspects of EBC have been discussed.