A80-3-26 Chronic Lymphocytic Leukemia in the Lung: A Nodular Presentation of a Systemic Disease

Abstract Pulmonary infiltrates in patients with chronic lymphocytic leukemia (CLL) are commonly a result of infection or inflammation in the setting of their immunocompromised state. Rarely, CLL itself may cause pathologic invasion of the lung parenchyma with malignant lymphocytes. This case describes the infiltrative appearance of a pulmonary nodule and history of leukemia, prompting the use of flow cytometry in conjunction with fine needle aspiration (FNA) and cryobiopsy to diagnose pulmonary involvement of CLL. The patient is a 63-year-old male with history of stage 1 CLL under surveillance and a recent admission for a left lower lobe pneumonia. Despite antibiotic therapy, the patient continued to experience fevers, fatigue, chest pain, cough, and weight loss. He was admitted to the hospital given concerns for persistent infection. CT imaging showed a left loculated pleural effusion, multi-station lymphadenopathy and an enlarging 1.0 x 1.3 cm left apical pulmonary nodule. Infectious disease recommended an extended three-week course of piperacillin-tazobactam for management of the complicated parapneumonic effusion. A repeat CT scan was performed to assess response and showed increase in nodule size to 2.1 x 1.6cm, describing a solid component with surrounding interlobular septal thickening and ground glass attenuation. These features raised suspicion for lymphangitic malignancy versus an opportunistic fungal infection. Robotic bronchoscopy was performed, with samples collected for tissue culture as well as flow cytometry. Fungal serologies were collected and ultimately negative. Pathology including cryobiopsies and FNA revealed atypical small lymphoid proliferation, with immunohistochemistry showing CD20 positive B cells. Flow cytometry performed on the sample was consistent with monotypic B cell population, confirming pulmonary involvement of the patient’s previously diagnosed CLL. This case highlights the need to consider CLL in the differential diagnosis of new pulmonary nodules, regardless of disease stability. Diagnostic confirmation through both tissue analysis and cytometry is essential when ruling out more common etiologies such as infection or secondary malignancy. Radiologic features that help differentiate CLL-related pulmonary nodules include well-defined, non-calcified appearance with the absence of spiculations. An important note when analyzing this CT scan is the presence of interlobular septal thickening, which may be mistaken for spiculations. Nodules may be solitary or multiple, or feature ground-glass opacities, vascular encasement or distortion of the underlying pulmonary architecture seen in more aggressive malignancies. The case demonstrates the importance of considering patient clinical presentation and radiologic findings, as well as pathologic tissue analysis and flow cytometry to confirm the diagnosis of CLL-related pulmonary nodules. This abstract is funded by: None