Diagnostic pitfalls of discriminating lymphoma-associated effusions

Clinical characteristics of chylothorax: results from the International Collaborative Effusion database

Background

Chylothorax is an uncommon medical condition for which limited data are available regarding the contemporary aetiology, management and outcomes. The goal of this study was to better define these poorly characterised features.

Methods

The medical records of adult patients diagnosed with chylothorax at 12 centres across Europe, America and South Africa from 2009-2021 were retrospectively reviewed. Descriptive and inferential statistics were performed.

Results

77 patients (median age 69 years, male to female ratio 1.5) were included. Subacute dyspnoea was the most typical presenting symptom (66%). The commonest cause of chylothorax was malignancy (68.8%), with lymphoma accounting for 62% of these cases. Other aetiologies were trauma (13%), inflammatory/miscellaneous conditions (11.7%) and idiopathic cases (6.5%). At the initial thoracentesis, the pleural fluid appeared milky in 73%, was exudative in 89% and exhibited triglyceride concentrations >100 mg·dL-1 in 88%. Lymphangiography/lymphoscintigraphy were rarely ordered (3%), and demonstration of chylomicrons in pleural fluid was never ascertained. 67% of patients required interventional pleural procedures. Dietary measures were infrequently followed (36%). No patient underwent thoracic duct ligation or embolisation. Morbidity included infections (18%), and thrombosis in malignant aetiologies (16%). The 1-year mortality was 47%. Pleural fluid protein >3.5 mg·dL-1 (sub-distribution hazard ratio (SHR) 4.346) or lactate dehydrogenase <500 U·L-1 (SHR 10.21) increased the likelihood of effusion resolution. Pleural fluid protein ≤3.5 mg·dL-1 (HR 4.047), bilateral effusions (HR 2.749) and a history of respiratory disease (HR 2.428) negatively influenced survival.

Conclusion

Chylothoraces have a poor prognosis and most require pleural interventions. Despite the standard recommendations, lymphatic imaging is seldom used, nor are dietary restrictions followed.

Hematolymphoid neoplasms in effusion cytology

Background:

Hematolymphoid neoplasms (HLNs) presenting as body cavity effusions are not a common finding. They may be the first manifestation of the disease. A diagnosis on effusion cytology may provide an early breakthrough for effective clinical management.

Aims:

Study the cytomorphology of HLNs in effusion cytology, determine common types, sites involved and uncover useful cytomorphologic clues to subclassify them.

Materials and Methods:

Twenty-four biopsy-proven HLN cases with malignant body cavity effusions and 8 cases suspicious for HLN on cytology but negative on biopsy are included in this study. Effusion cytology smears were reviewed for cytomorphological features: cellularity, cell size, nuclear features, accompanying cells, karyorrhexis, and mitoses.

Results:

Diffuse large B-cell lymphoma (37%) was the most common lymphoma type presenting as effusion followed by peripheral T-cell lymphoma (25%). Pleural effusion (75%) was most frequent presentation followed by peritoneal effusion (20.8%). Pericardial effusion was rare (4.1%). The common cytologic features of HLNs in effusions: high cellularity, lymphoid looking cells with nuclear enlargement, dyscohesive nature, and accompanying small lymphocytes. Mitosis and karyorrhexis were higher in high-grade HLNs when compared to low-grade HLNs. Myelomatous effusion showed plasmacytoid cells. Very large, blastoid looking cells with folded nuclei, high N: C ratio, and prominent nucleoli were seen in leukemic effusion.

Conclusion:

HLNs have characteristic cytomorphology and an attempt to subclassify them should be made on effusion cytology. Reactive lymphocyte-rich effusions cannot be distinguished from low-grade lymphomas based on cytomorphology alone. Ancillary tests such as immunocytochemistry, flow cytometry, and/or molecular techniques may prove more useful in this regard.

Identifying Thoracic Malignancies Through Pleural Fluid Biomarkers: A Predictive Multivariate Model

The diagnosis of malignant pleural effusions may be challenging when cytological examination of aspirated pleural fluid is equivocal or noncontributory. The purpose of this study was to identify protein candidate biomarkers differentially expressed in the pleural fluid of patients with mesothelioma, lung adenocarcinoma, lymphoma, and tuberculosis (TB).A multiplex protein biochip comprising 120 biomarkers was used to determine the pleural fluid protein profile of 29 mesotheliomas, 29 lung adenocarcinomas, 12 lymphomas, and 35 tuberculosis. The relative abundance of these predetermined biomarkers among groups served to establish the differential diagnosis of: malignant versus benign (TB) effusions, lung adenocarcinoma versus mesothelioma, and lymphoma versus TB. The selected putative markers were validated using widely available commercial techniques in an independent sample of 102 patients.Significant differences were found in the protein expressions of metalloproteinase-9 (MMP-9), cathepsin-B, C-reactive protein, and chondroitin sulfate between malignant and TB effusions. When integrated into a scoring model, these proteins yielded 85% sensitivity, 100% specificity, and an area under the curve (AUC) of 0.98 for labeling malignancy in the verification sample. For lung adenocarcinoma-mesothelioma discrimination, combining CA19-9, CA15-3, and kallikrein-12 had maximal discriminatory capacity (65% sensitivity, 100% specificity, AUC 0.94); figures which also refer to the validation set. Last, cathepsin-B in isolation was only moderately useful (sensitivity 89%, specificity 62%, AUC 0.75) in separating lymphomatous and TB effusions. However, this last differentiation improved significantly when cathepsin-B was used with respect to the patient's age (sensitivity 72%, specificity 100%, AUC 0.94).In conclusion, panels of 4 (i.e., MMP-9, cathepsin-B, C-reactive protein, chondroitin sulfate), or 3 (i.e., CA19-9, CA15-3, kallikrein-12) different protein biomarkers on pleural fluid samples are highly discriminative for signaling a malignant versus tuberculous effusion, or lung adenocarcinoma versus mesothelioma, respectively. Cathepsin-B could also be helpful in establishing the presence of a lymphomatous effusion versus that of TB, if the patient's age is simultaneously taken into consideration.