A 73 year-old African-American female with history Rai Stage 3 Chronic Lymphocytic Leukemia (CLL), not on any treatment was admitted with sepsis secondary to cellulitis of right leg. On the seventh day of hospitalization she became acutely dyspneic. On evaluation, blood pressure was 100/70 mmHg, heart rate 110 beats/min, respiratory rate 21 per min and saturated at 64% on room air. Chest auscultation revealed bilateral crackles. She had a white cell count of 81k cells/L with 73% lymphocytes and 15% neutrophils. Arterial blood gas analysis showed pAO2 55 mmHg, pACO2 35 mmHg and pH 7.33. Computed tomography of the chest revealed extensive bilateral consolidation. She was empirically treated for health care associated pneumonia with vancomycin and piperacillin/tazobactam. Hypoxia kept worsening and required intubaton with positive pressure ventilation. Work up with blood and sputum cultures were negative. Bronchoscopy showed normal proximal airways. Bronchoalveolar lavage (BAL) was negative for bacterial and fungal culture, silver staining and flowcytometry. She did not respond to initial treatment and eventually required tracheostomy and prolonged mechanical ventilation. Open lung biopsy was done. Histopathology showed infiltration of pulmonary parenchyma by monoclonal lymphocytes. At this point she was treated with high dose methylprednisone along with Fludarabine & Rituximab based chemotherapy. She reponded well and was eventually weaned from mechanical ventilator after nealy a month.
Discussion:
CLL represents an immunocompromised state. Therefore, infection is always suspected when a patient with CLL presents with pulmonary infiltrates. However, leukemic infiltration of the lung has a very similar presentation and should be considered in the differential diagnosis, especially in a patient with negative cultures and failure to repond to antibiotics. Pulmonary involvement is mostly seen in advanced CLL. However, no correlation has been found between presence of pulmonary involvement and absolute lymphocyte count. BAL can be diagnositc but is less sensitive. Lung biopsy (Open/Transbronchial) establishes a definitive diagnosis but is seldom performed due to its invasive nature. Transbronchial biopsy may be less yielding due to patchy nature of infiltrates. Corticosteroids provide initial symptomatic relief with resolution of pulmonary infiltates due to its cytolytic effect on leukemic cells. Antineoplastic therapy directed against CLL remains the mainstay of treatment. Long term remissions have been reported in patients treated with aggresive chemotherapy.
Conclusions:
Pulmonary leukemic infiltrate may present like pneumonia both clinically and radiologically. It should be considered as a differential diagnosis in a patient with leukemia specially when unresponsive to antibiotics and conservative measures.