C45-08 An Unexpected Tap: A Case of Chronic Lymphocytic Leukemia Presenting as a Pleural Effusion

Abstract Although chronic lymphocytic leukemia (CLL) is the most common adult hematologic malignancy, pleural involvement is rare and usually occurs at an advanced stage. We present a case of CLL whose pleural involvement was the only manifestation and was incidentally found by thoracentesis. A seventy-four-year-old woman with chronic respiratory failure secondary to chronic obstructive lung disease (COPD), atrial fibrillation, and heart failure with preserved ejection fracture (HFpEF) presented with a three-day history of productive cough and shortness of breath. On examination, the patient was hemodynamically stable, though oxygen saturation was 86% on her baseline 2L supplemental oxygen. Physical exam was negative for lymphadenopathy or splenomegaly and showed reduced lung sounds at the right base. Laboratory findings revealed a leukocytosis of 13.9 g/dL with normal differential, hemoglobin of 9.6 g/dL, and iron studies consistent with iron deficiency. Troponins, procalcitonin, respiratory viral culture, b-natriuretic peptide, legionella, and streptococcus serologies were normal. Chest radiography showed concern for a right basilar opacity and unilateral pleural effusion. She was initiated on empiric treatment of COPD exacerbation secondary to community acquired pneumonia. Diagnostic thoracentesis revealed serous colored fluid that was exudative with lymphocyte predominance. When initial bacterial, fungal, and mycobacterium cultures were negative, cytology and flow cytometry was performed and revealed CD5 positive lambda restricted cells with B cell lymphocytosis morphology and an identical monoclonal B cell population, respectively. She was referred to hematology oncology outpatient for positron emission tomography (PET) scan and further discussion about treatment.Pulmonary complications in chronic lymphocytic leukemia (CLL) occur in 4-7% of cases and usually in advanced disease. The differential includes infection due to immunosuppression, pneumonitis due to treatment, or pleural effusion due to multifactorial etiologies. We present a case of pleural effusion as the sole and initial manifestation of CLL. Proposed mechanisms of pleural effusions in CLL include lymphatic obstruction from infiltration of mediastinal lymph nodes, thoracic duct obstruction, and direct growth of malignant cells into the pleura. The incidence of pleural involvement as initial presentation of CLL is unknown but rare and only seen in other case reports. This patient had a pleural effusion without mediastinal involvement and whose leukocytosis was initially felt to be in the setting of infection. Physicians should consider CLL as a cause of incidental pleural effusion even in the absence of other consistent laboratory or physical exam findings, as the presence of pleural involvement has been associated with poorer prognosis. This abstract is funded by: None