Investigating unilateral pleural effusions: the role of cytology

Abstract

The vast majority of undiagnosed unilateral pleural effusions have fluid sent for cytological analysis. Despite widespread use, there is uncertainty about its sensitivity to diagnose malignant pleural effusions (MPEs). Our aim was to ascertain the utility of cytology using a large prospective cohort.Consecutive patients presenting with an undiagnosed unilateral pleural effusion were recruited to this UK-based study. All had pleural fluid sent for cytological analysis. Cytological sensitivity was based on the final diagnosis at 12 months, confirmed by two consultants.Over 8 years, 921 patients were recruited, of which 515 had a MPE. Overall sensitivity of fluid cytology to diagnose malignancy was 46% (95% CI 42–58%). There was variation in sensitivity depending on cancer primary, with mesothelioma (6%) and haematological malignancies (40%) being significantly lower than adenocarcinomas (79%). MPEs secondary to ovarian cancer had high pick-up rates (95%). In asbestos-exposed males with exudative effusions, the risk of MPE was 60%, but cytological sensitivity was 11%.This is the largest prospective study of pleural fluid cytology and informs discussions with patients about the likely requirement for investigations following thoracentesis. In patients presenting with a clinical suspicion of mesothelioma, cytological sensitivity is low, so more definitive investigations could be performed sooner.

Biomarkers in the diagnosis of pleural diseases: a 2018 update

“… * Information from references 4, 10, 12, 25, 28, 31, 38, 40, 44, 52 and 53. $ For labeling mesothelioma. ‡ For distinguishing malignant from benign mesothelial proliferations. § For non-small cell lung cancer. ADA, adenosine deaminase; CEA, carcinoembryonic antigen; CT, computed tomography; EGFR, epidermal growth-factor receptor; FISH, fluorescence in situ hybridization; ICC, immunocytochemistry; NT-proBNP, amino-terminal fragment of probrain natriuretic peptide; PF, pleural fluid; S−PF, serum minus pleural fluid levels. …”

Diagnostics in Pleural Disease

“…Diagnosing an MPE through PF poses some challenges. Historically, PF cytology yields were suggested to be 60%; however, more recent data would suggest that this is likely an overestimation [13,[47][48][49]. It is suggested that 50-75 mL should be sent as a minimum to maximise yield and a repeat fluid cytology may increase the yield by a further 26%, though this latter claim is based on a small retrospective series [50,51].…”

“…There exists a heterogeneity for yield, varying according to underlying tumour type. Typically, ovarian and breast cancer have a high diagnostic yield in PF (94.7% and 70.7%, respectively), lung adenocarcinoma fares the best of the lung cancers (82%), whilst mesothelioma fares particularly poorly (6.1%) [47].…”

Malignant Pleural Effusion From Squamous Cell Carcinoma of the Vulva: Extremely Rare Metastatic Pattern of A Rarely Metastasizing Cancer

“…withdrawn during thoracentesis and processed for cytology. The approximate overall cytological yield in MPE is a disappointing 50%, a number that can exceed 80% in exfoliative cancers such as ovarian adenocarcinoma and can fall under 30% in non-exfoliative cancers such as SCC [8,9]. It…”