Abstract Most malignant effusions are mononuclear predominant, with only 16-20% being neutrophilic. Neutrophilic predominance should raise suspicion for secondary inflammatory process, particularly empyema. In absence of infection, elevated neutrophils can be a sign of tumor necrosis or tumor lysis. In malignant pleural effusions, markers such as low glucose, low pH, and high LDH may indicate a high tumor burden and are markers of poor outcomes. 64-year-old male with past medical history of metastatic mucinous lung adenocarcinoma status post diagnostic right lower lobe wedge resection and recurrent bilateral malignant pleural effusions, presented to outpatient clinic for therapeutic right-sided thoracentesis. 900 mL of viscus green-brown pleural fluid was removed, and initial fluid studies revealed a neutrophil-predominant exudate with 45,045 total nucleated cells (TNCs) and pH of 7.01. Given concern for infection the patient was admitted, and a right-sided 14 French pigtail pleural catheter was placed. Left-sided thoracentesis was also performed, with pleural fluid studies consistent with a lymphocytic exudate. Vitals on admission were all within normal limits and white blood cell count was 8.9. Chest computed tomography (CT) scan showed extensive bilateral lymphangitic metastases scattered throughout both lungs and bilateral hydropneumothoraces with evidence of a left-sided pleural rind. Infectious workup, including pleural fluid cultures and broad-range bacterial polymerase chain reaction (PCR) were all negative. Cytology of both left and right pleural fluid revealed malignant adenocarcinoma with a substantial amount of necrosis. Patient was discharged home on oral antibiotics with plan to follow up as outpatient for possible tunneled pleural catheter placement. Post-discharge, patient continued to receive intermittent therapeutic thoracenteses. Subsequently readmitted, again with concerns for empyema, bilateral tunneled pleural catheters were placed after infectious workup was again unrevealing. At one month follow up, he reported drainage of 300-500 mL of pleural fluid with alternating daily drainages without complication. Differentiating neutrophilic malignant pleural effusions from empyema is clinically difficult and can lead to delay in definitive pleural treatments. Although it is important to rule out infection, malignancy should remain on one’s differential diagnosis, particularly if the remainder of the patient’s history and presentation are inconsistent with an infectious etiology. This abstract is funded by: None
Mangin et al. (Fri,) studied this question.