ACUTE MYELOMONOCYTIC LEUKEMIA PRESENTING AS PULMONARY INFILTRATES SECONDARY TO LEUKEMIC INFILTRATION

Abstract

SESSION TITLE: Lung Pathology 1 SESSION TYPE: Fellow Case Report Posters PRESENTED ON: 10/09/2018 01:15 PM - 02:15 PM INTRODUCTION: Malignant infiltration of pulmonary parenchyma is a rare complication of acute myeloid leukemia and commonly found on autopsy of patients without prior clinical pulmonary symptoms. We present a case of a 75-year-old female with acute myelomonocytic leukemia presenting as rapidly progressive respiratory failure with pulmonary leukemic infiltration. CASE PRESENTATION: The patient presented to her local hospital after 2 weeks of fevers, chest pain, dyspnea, and a non productive cough. CT angiogram of her chest revealed bilateral diffuse pulmonary infiltrates, loculated pleural effusions, and no evidence of pulmonary embolism. She underwent a left thoracentesis that yielded 13ml of an exudative effusion with following counts (RBCs 16 k/uL, WBCs 5.8 k/uL with 41% neutrophils, 8% lymphocytes, 6% monocytes, 43% macrophages & 2% mesothelial cells), as well as negative cultures and cytology. Due to progression of respiratory failure despite broad spectrum antimicrobials over the next 5 days, and new onset of atrial fibrillation, she was transferred to our hospital. Initial blood counts revealed abnormal peripheral monocytosis (AMC 1.8 k/uL, 32%) with a normal WBC count at 5.6 k/uL. Peripheral smear revealed premature monocytes. Her respiratory failure continued to progress requiring mechanical ventilation. She underwent exploratory thoracoscopy, lung wedge resection and intraoperative bronchoalveolar lavage. Lavage was significant for a WBC count of 400 per uL, 66% of which were monocytes. Lavage and pleural fluid cytologies were negative for malignant cells. Follow up blood counts showed progression of her monocytosis with appearance of promonocytes and peripheral blasts. Peripheral blood flow cytometry revealed 6% atypical myeloblasts and 45% atypical monocytic cells. Pleural and lung biopsies revealed an atypical interstitial mononuclear cell infiltrate with monocytic differentiation consistent with involvement by myeloid leukemia. Faced with refractory shock, multiorgan failure, and the most likely diagnosis of of acute leukemia, her family elected to transition to comfort measures and refused a bone marrow biopsy for diagnostic confirmation. She was palliatively extubated and passed away 4 days after her transfer. Autopsy was performed and confirmed acute myelomonocytic leukemia with leukemic infiltration of lungs, pleura, pericardium and spleen. DISCUSSION: Malignant infiltration of the lung is a rare manifestation of acute myeloid leukemia. We presented a case of progressive respiratory failure secondary to pulmonary and pleural involvement as an early presentation of acute myelomonocytic leukemia with a fatal outcome. CONCLUSIONS: Although uncommon, leukemic lung infiltration remains in the differential of acute pulmonary infiltrates in setting of blood dyscrasias suggestive of acute myeloid leukemia and can cause profound respiratory failure before a leukemia diagnosis is established. Reference #1: Wu Y-K, Huang Y-C, Huang S-F, Huang C-C, Tsai Y-H. Acute respiratory distress syndrome caused by leukemic infiltration of the lung. J Formos Med Assoc. 2008;107(5):419-423. Reference #2: Koh TT, Colby TV, Müller NL. Myeloid leukemias and lung involvement. Semin Respir Crit Care Med. 2005;26(5):514-519 Reference #3: Hildebrand FL, Rosenow EC, Habermann TM, Tazelaar HD. Pulmonary complications of leukemia. Chest. 1990;98(5):1233-1239 DISCLOSURES: No relevant relationships by Abdallah Abboud, source=Web Response No relevant relationships by Timothy Dwyer, source=Web Response No relevant relationships by Kathryn Gillen, source=Web Response No relevant relationships by Joel Mermis, source=Web Response No relevant relationships by Mitchell Tener, source=Web Response