Diagnostic utility of pleuroscopic guided pleural biopsy versus pleural fluid cell block in the diagnosis of malignant pleural effusion

INTRODUCTION: Pleural biopsy using flex-rigid pleuroscopy or pleural effusion cell block analysis is useful for diagnosing malignant pleural effusion. However, the current literature lacks documented comparisons between pleural biopsies and cytological cell blocks. This study aims to compare the diagnostic accuracy of pleural biopsy and cytological cell block in identifying malignant pleural effusion.

MATERIALS AND METHODS: A retrospective review was conducted on patient data from those who underwent pleuroscopy at Hospital Canselor Tuanku Muhriz from January 2021 to December 2023. We included patients with pleural effusion who underwent both cell block and pleural biopsy with a confirmed diagnosis of malignancy through histopathological examination. At least 200 ml of pleural fluid was collected, followed by the biopsy of six or more pleural tissue samples.

RESULTS: Out of the 196 pleuroscopy procedures analysed, 91 patients were diagnosed with malignant pleural effusion. Malignancy was diagnosed in 50 (54.9%) cases using cell block analysis, whereas pleural biopsy identified malignancy in 81 (89%) cases. The diagnostic yield was significantly higher for pleural biopsy compared to pleural fluid cell block [89% (81/91) vs. 54.9% (50/91); p < 0.001]. Among patients with negative results on pleural fluid cell block, 33 (36.3%) had positive results on pleural biopsy. The definitive diagnoses of malignancy included 64 (70.3%) cases of lung adenocarcinoma, 4 (4.4%) cases of lung squamous carcinoma, 2 (2.2%) cases of small cell lung cancer, 2 (2.2%) cases of mesothelioma, and 19 (20.9%) cases of metastatic carcinoma. Eight (8.8%) patients exhibited negative findings on both pleural fluid cell block and pleural biopsy. Further diagnoses were achieved through computed tomography-guided needle tru-cut biopsy of the lung in 6 patients (6.6%), transbronchial lung biopsy in 1 patient (1.1%), and cervical lymph node biopsy in 1 patient (1.1%).

CONCLUSION: Pleural biopsy exhibits superior diagnostic accuracy compared to pleural fluid cell block analysis for malignant pleural effusion. In cases where cell block results are negative but suspicion remains high, pleural biopsy remains a crucial diagnostic tool.