Pericardial fluid specimen volumes ≥50 mL were associated with a significantly higher malignancy rate compared to <50 mL (18.4% vs 10.6%; OR 1.91, 95% CI 1.43-2.55, p<0.001).
Observational (n=1,591)
No
Does a submitted pericardial fluid volume of ≥50 mL improve the likelihood of a malignant cytologic diagnosis compared to <50 mL in patients with pericardial effusions?
Submitting at least 50 mL of pericardial fluid significantly increases the diagnostic yield for detecting malignant cells, with diminishing incremental benefit beyond 100 mL.
Odds Ratio: 1.91 (95% CI 1.43–2.55)
Absolute Event Rate: 18.4% vs 10.6%
p-value: p=<0.001
Introduction: Cytologic examination of pericardial effusions is critical for detecting malignant involvement, which carries a dismal prognosis. However, contemporary large-scale studies characterizing the distribution of metastatic tumor and the impact of submitted fluid volume on diagnostic yield remain limited. This study evaluates the distribution of metastatic tumors in malignant pericardial effusions and examines the relationship between specimen volume and likelihood of malignant cytologic diagnosis in a large institutional cohort. Methods: A 10-year retrospective review was performed of all pericardial fluid cytology specimens accessioned at a large tertiary academic medical center. Clinical, radiologic and cytologic findings were recorded. Cases categorized as suspicious for malignant cells (SFM) or malignant were included in the metastatic tumor distribution analyses after reviewing tumor cytomorphology and immunohistochemical profile, in conjunction with clinical and radiologic data. Specimen volumes were stratified by diagnostic category, and threshold-based analyses at 50 mL and 100 mL were compared across diagnostic categories using statistical methods. Results: A total of 1,591 cases were identified from patients of median age 65 years and male-to-female ratio 0.98. Most cases were negative for malignant cells (NFM) (78.6%), while 14.4% classified as malignant (MAL). Among malignant cases (SFM + MAL), carcinomas accounted for 83.5%, followed by hematolymphoid malignancies (14.0%); mesotheliomas, sarcomas, and melanomas were rare. Lung carcinoma was the most common primary tumor (48.0%), followed by breast carcinoma (16.0%) and B-cell lymphoma (7.8%). Submitted specimen volume increased progressively across diagnostic categories (p=0.0010), with malignant cases demonstrating higher median volumes than negative cases. Specimens ≥50 mL showed a significantly higher malignancy rate compared with those <50 mL (18.4% vs 10.6%, p < 0.001), corresponding to nearly twofold increased odds of malignancy (OR 1.91, 95% CI 1.43–2.55). A smaller but statistically significant association was observed at the 100 mL threshold (OR 1.35, 95% CI 1.06–1.82), with no additional benefit at higher thresholds. Conclusions: In this 10-year institutional experience, malignant pericardial effusions were overwhelmingly metastatic in origin, most commonly arising from lung and breast carcinomas and hematolymphoid malignancies. Awareness of the metastatic distribution to the pericardium enhances diagnostic confidence and guides immunohistochemical workup on specimens with limited cellularity. Submitted fluid volume was significantly associated with malignant cytologic diagnosis, with volumes ≥50 mL conferring nearly twofold increased odds of malignancy and diminishing incremental benefit beyond 100 mL. These findings support submission of at least 50 mL of pericardial fluid when clinically feasible to optimize diagnostic yield and inform appropriate ancillary testing.
Marshall et al. (Fri,) conducted a observational in Pericardial effusions (n=1,591). Specimen volume ≥50 mL vs. Specimen volume <50 mL was evaluated on Malignant cytologic diagnosis (OR 1.91, 95% CI 1.43-2.55, p=<0.001). Pericardial fluid specimen volumes ≥50 mL were associated with a significantly higher malignancy rate compared to <50 mL (18.4% vs 10.6%; OR 1.91, 95% CI 1.43-2.55, p<0.001).