Fluorescence in situ hybridization, comparative genomic hybridization, and other molecular biology techniques in the analysis of effusions

Molecular testing on serous effusion: An update

Cytological examination of the effusion fluid provides valuable information regarding the presence of malignancy. At times, it is challenging to diagnose malignant cells in serous effusion. The various ancillary techniques are available to solve the problem including immunocytochemistry, DNA ploidy, and multicolored flow cytometry. At present, the molecular tests on the effusion sample are of growing interest. The effusion sample is rich in cells and cell-free fluid that contains free DNA, cytokines, and extracellular vesicles. Molecular tests in effusion sample not only provide a diagnosis of malignancy but can also give valuable information that may be essential for the individualized therapy, management, and prognostic assessment. In this paper, we reviewed the application of the different molecular tests in the effusion sample.

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.

Efficacy of two fluorescence in situ hybridization (FISH) probes for diagnosing malignant pleural effusions

It is difficult to differentiate tumor cells in pleural fluid from reactive benign mesothelium. Fluorescence in situ hybridization (FISH) can increase diagnostic accuracy. Two hundred pleural fluid samples were analyzed by using FISH probes for chromosomes 11 and 17. Histological analysis was used to diagnose cancer. Clinical, radiological, and histological data were used to exclude malignancy. Eighty-two pleural effusion samples had positive cytology, 51 were benign, and 67 were atypical, but inconclusive. The 82 positive cases were confirmed to be malignant. Among the 51 negative cytology cases, videothoracoscopy-guided pleural biopsy revealed malignancy in three; aneuploid cells were detected by FISH in all cases. In 43 of the 67 cases with inconclusive cytology, malignancy was confirmed based on histology and fluorescence in situ hybridization. One case of parapneumonic effusion with no evidence of cancer during clinical follow-up had a suspicious cytology and positive fluorescence in situ hybridization result. The remaining 23 cases had no histological, radiological, clinical, or genetic evidence of malignancy. This study demonstrated that cytogenetic analysis of fresh pleural fluid samples using only two FISH probes is a valuable ancillary method for the identification of malignant pleural effusion, particularly in cases in which oncotic cytology is inconclusive.

Chromosomal aberrations detected by chromogenic in situ hybridization in abdominal wall endometriosis after cesarean section

The goal of this study is to evaluate the chromosomal loss in abdominal wall endometriosis by chromogenic in situ hybridization (CISH). Twenty-four cases of abdominal wall endometriosis that developed after cesarean section at the Korea University Medical Center between January 1997 and December 2006 were selected. CISH was performed in the sections of tissue microarray block using the Zymed CISH centromeric probes for chromosomes 3, 7, 8, 9, 10, 11, 17, and 18. Monosomy was defined when the percentage of the nuclei with a single dot was more than mean+3 SD of the respective probe in normal control endometrium. CISH study was possible in more than half of the endometriosis samples, except for chromosome 9, and was most successful for chromosome 17. The frequency of monosomy was high for chromosomes 9 (75.0%) and 17 (73.9%), moderate for chromosomes 10 (57.1%) and 18 (56.3%), and low for chromosomes 3 (12.5%), 7 (22.2%), 8 (10.5%), and 11 (10.5%). Monosomy for >2 and 3 chromosomes occurred in 66.7% and 42.9% of the cases, respectively. It is concluded that CISH method may be considered a useful laboratory technique in detecting chromosomal loss, and multiple chromosomal loss is involved in the formation of ectopic endometrium in abdominal wall endometriosis.

Diagnostic molecular biomarkers for malignant pleural effusions

Malignant pleural effusions (MPEs) are a common and important cause of cancer-related mortality and morbidity. Prompt diagnosis using minimally invasive tests is important because the median survival after diagnosis is only 4–9 months. Pleural fluid cytology is pivotal to current MPE diagnostic algorithms but has limited sensitivity (30–60%). Consequently, many patients need to undergo invasive diagnostic tests such as thoracoscopic pleural biopsy. Recent genomic, transcriptomic, methylation and proteomic studies on cells within pleural effusions have identified novel molecular diagnostic biomarkers that demonstrate potential in complementing cytology in the diagnosis of MPEs. Several challenges will need to be addressed prior to the incorporation of these molecular tests into routine clinical diagnosis, including validation of molecular diagnostic markers in well-designed prospective, comparative and cost–effectiveness studies. Ultimately, minimally invasive diagnostic tests that can be performed quickly will enable clinicians to provide the most effective therapies for patients with MPEs in a timely fashion.

Prognostic impact of RT-PCR-based detection of peritoneal micrometastases in patients with pancreatic cancer undergoing curative resection

BACKGROUND

Positive peritoneal fluid cytology predicts poor outcome in patients with resected pancreatic cancer. Reverse transcription-polymerase chain reaction (RT-PCR) has been proposed as a more sensitive means of detection of peritoneal micrometastases than conventional cytology. The clinical significance of RT-PCR positivity in the absence of other evidence of peritoneal disease is unknown. The purpose of the current study was to determine the outcome RT-PCR positive/cytology-negative patients who underwent potentially curative resection.

METHODS

Peritoneal washings were collected prospectively from 115 patients with pancreatic cancer undergoing diagnostic laparoscopy at a single institution. Specimens were analyzed by a cytopathologist and by RT-PCR for carcinoembryonic antigen (CEA).

RESULTS

Of the 115 patients, 62 (54%) underwent R0 resection. Eleven of the 62 patients (18%) had peritoneal washings that were negative by conventional cytology but positive for CEA by RT-PCR. Those 11 patients experienced early peritoneal and overall disease recurrence versus those who were RT-PCR negative (P = 0.001, P = 0.003, respectively) independent of nodal status.

CONCLUSIONS

RT-PCR for CEA is a sensitive and specific method for the detection of clinically significant peritoneal micrometastases from pancreatic cancer and it might identify a subgroup of patients with otherwise negative findings at staging laparoscopy who might respond better to treatment other than primary surgical resection.