Performance of the UroVysion® FISH assay for the diagnosis of malignant effusions using two cutoff strategies.

The cytological examination of cavity fluids has limited sensitivity in the diagnosis of malignancy. Aneuploidy, which is commonly observed in neoplastic cells, could potentially be used as an ancillary diagnostic tool. To evaluate the detection of aneuploid cells in cavitary effusion samples using the fluorescence in situ hybridization (FISH) assay UroVysion® with some adaptations and two different cutoff strategies. Seventy samples of pleural or peritoneal fluid with positive (n = 40), negative (n = 15), or suspicious (n = 15) oncotic cytology were subjected to FISH assay with the multitarget UroVysion® kit, which is composed of probes that hybridize to the centromeric region of chromosomes 3, 7, and 17 and to the locus 9p21. FISH performance was evaluated using two different cutoffs: (1) the manufacturer's cutoff (M-FISH) and 2) a proposed cutoff (P-FISH). Using M-FISH, the diagnostic sensitivity was 57.1%, specificity 87.5%, and accuracy 60.0%; with P-FISH, the sensitivity was 87.3%, specificity 71.4%, and accuracy 85.7%. When combined with cytology, the sensitivity, specificity, and accuracy were 88.0%, 83.3%, and 87.8%, respectively. Malignant cells presented a predominance of chromosomal gains. The UroVysion® test using the P-FISH cutoff was effective in demonstrating aneuploid cells in all malignant effusions, confirming the diagnosis of malignancy even in cases with suspicious cytology.

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.