SESSION TITLE: Infectious Disease Student/Resident Case Report Posters II
SESSION TYPE: Medical Student/Resident Case Report
PRESENTED ON: Tuesday, October 28, 2014 at 01:30 PM - 02:30 PM
INTRODUCTION: Nontuberculous mycobacteria pulmonary infections are often due to Mycobacterium Avium Complex (MAC) . Few cases reported MAC causing lung mass. Radiographically, the form of MAC without known underlying lung disease could be associated with lung nodules . We present a patient with chronic cough whose workup for lung masses revealed MAC.
CASE PRESENTATION: A previously healthy 57-year-old female with no immunodeficiency presented with a 4-month history of progressive dyspnea, chest pain, and cough with productive clear sputum. She manifested chills and night sweats without any weight changes. Imaging included a chest x-ray that revealed right and lower lobe infiltrative opacities. A CT angiography of the chest (Fig 1) was consistent with a right lung infiltrates that revealed a 9 x 6.5 cm mass along the right upper lobe and a 2.6 x 7.4 cm mass in the right lower lobe. Eosinophilia was up to 2.38 K/uL. Her Quantiferon TB test and AFB were negative. Gram stain, bacterial, and fungal cultures were negative. She received Azithromycin and Piperacillin/Tazobactam for community-acquired and post-obstructive pneumonia respectively. Bronchoscopy showed mucosal erythema and edema without endobronchial mass. Transbronchial biopsies revealed no granulomas or malignant cells. A CT-guided biopsy of the right upper lobe lesion showed fibrin deposition, macrophages/CD68 positive, S-100 negative, CD1a negative and many eosinophilic infiltrations with no evidence of eosinophilic granuloma. These findings were suggestive of eosinophilic pneumonia (Fig 2). The patient was started on prednisone to treat the eosinophilic pneumonia. Eight weeks following her bronchoscopy, her cultures were positive for MAC. Ethambutol, Rifampin and Clarithromycin were initiated.
DISCUSSION: MAC rarely presents as a lung mass  and has never been associated with eosinophilic pneumonia. The diagnosis of MAC was essential to change the course of treatment from eosinophilic pneumonia to MAC infection associated with eosinophilic pneumonia. Following therapy, a repeated CT of the chest showed interval improvement. Medical and/or surgical resection could effectively treat the lung masses caused by MAC .
CONCLUSIONS: Physicians and pulmonologists should consider MAC in the differential diagnosis of lung mass despite primary negative workup and unusual radiologic and pathologic findings. MAC pulmonary infection can be misdiagnosed with lung cancer. Eosinophilic pneumonia, however, has never been associated with MAC.
Reference #1: Johnson MM, Odell JA. Nontuberculous mycobacterial pulmonary infections. J Thorac Dis. 2014 Mar; 6(3):210-220.
Reference #2: Reich JM, Johnson RE. Mycobacterium Avium Complex pulmonary disease presenting as an isolated lingular or middle lobe pattern. The Lady Windermere syndrome. Chest. 1992 Jun; 101(6):1605-9.
Reference #3: Matsuoka T, et all. MAC infection needed differential diagnosis of the recurrence after surgery for double lung cancer; report of a case. Kyobu Geka. 2007 Dec; 60(13):1200-3.
DISCLOSURE: The following authors have nothing to disclose: Jimmy Doumit, Patrick Ters, Janel Harting
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