Fluorescence thoracoscopy in the detection of pleural malignancy

Conventional thoracoscopy, routinely performed in patients with pleural diseases, is not always conclusive in staging of pleural spread. Fluorescence diagnosis (FD) with 5-aminolaevulinic acid (5-ALA) has been used in the diagnostic purpose for various malignancies. The impact of fluorescence thoracoscopy on diagnosis and staging of pleural malignancies was examined. A total of 23 patients with non-conclusive pleural effusions were enrolled in the prospective single-institution trial. Eligible patients were administered 25 mg/kg of 5-ALA ('Alasense', Niopik, Russian Federation) per os 3 h before video-assisted thoracoscopy. After conventional inspection with white light, thorough fluorescence investigation of the visceral and parietal pleura was performed (D-LIGHT Auto Fluorescent System, Karl Storz, Germany). Biopsy specimens of both normal and abnormal sites, as determined from white-light and FD inspection, were obtained for histological examination. There was no morbidity or mortality due to the procedure. A definitive diagnosis was obtained in all cases: malignant mesothelioma in 13 cases, other malignancies (pleural metastases) in 8 cases and non-specific inflammation in 3 patients. A total of 118 biopsy specimens were available for histological examination. In 20 patients, all pleural deposits (n = 60) detected by white-light thoracoscopy had bright red fluorescence during FD and were proved to be malignant. Upstaging occurred in 12 patients (57.2%) (unsuspected 21 tumour deposits) due to FD examination. Micrometastases of macroscopically normal pleura were detected, only by FD, in one patient. Comparing the results of histological examination of specimens detected by conventional thoracoscopy with that by fluorescence thoracoscopy, we obtained 82 true positive, 10 false-negative, 23 true negative, 3 false-positive results with a specificity of 88.4%, sensitivity of 89.1% and diagnostic accuracy of 88.9%. FD using 5-ALA in the pleural cavity is a feasible diagnostic tool when used in addition to white-light thoracoscopy. It improves visualization of additional lesions or even micrometastases in patients with pleural malignancy.