View Abstract

A5442 - The Lung Mass Masquerade
Author Block: J. D'Amico, E. M. Knauft; Pulmonary and Critical Care Medicine, Maine Medical Center, Portland, ME, United States.
Introduction: Actinomycosis is a rare bacterial infection infrequently involving the thoracopulmonary system. Clinically, infections mimic malignancy and chronic infections making the diagnosis elusive. Actinomyces israelli is the most common pathogen(1). Actinomyces odontolyticus is a less common cause of infection(2). Case Presentation: A 70 year old homeless male with history of Chronic Obstructive Pulmonary Disease, 90 pack year smoking history, alcohol abuse and asbestos exposure presents with one year of hemoptysis, 50 pound weight loss and night sweats. He was incarcerated for 30 years with CT scan upon his release six months before presentation showing a 4.7 cm right lower lobe (RLL) mass. Four months later he sought medical care and had sputum Acid fast stain negative x 3 and a negative PPD. PET scan showed a peripherally avid 6.7 cm x 7.4 cm RLL mass with central necrosis. Positive mediastinal nodes at ATS station 2R, 4R, 7, AP stations and a 1.5 cm avid left adrenal nodule were noted. Endobronchial ultrasound with transbronchial node aspiration was negative for malignancy at ATS stations 4L and 7. Endobronchial biopsies and brush of RLL were negative. Bronchoalveolar lavage RLL grew Streptococcus pneumonia, Haemophilis influenza, Moraxella cattarhallis. CT guided transthoracic biopsy of mass showed necrotic tissue and patient was referred for video assisted thoracoscopy (VATS). Before VATS, he presented septic with right hydropneumothorax requiring chest tube and broad spectrum antibiotics. Pleural fluid showed empyema and culture grew Actinomyces odontolyticus and Streptococcus anginosus. He improved with 4 weeks of intravenous Unasyn and was discharged with 6 months of oral doxycycline. After one month of partial compliance, he returned septic, and despite broad spectrum antibiotics the mass enlarged to 8.9 cm x 8.4 cm invading the right middle lobe with clot extension into the left atrium and pulmonary vein. The adrenal nodule increased in size prompting adrenal biopsy which showed Large Cell Carcinoma. Discussion: We present an uncommon case of thoracopulmonary Actinomyces odontolyticus infection coexisting with Large Cell Lung Carcinoma. To our knowledge, there are only 15 reported cases of thoracopulmonary disease due to Actinomyces odontolyticus(2,3). The diagnosis is challenging and can mimic malignancy with adrenal metastatic disease(4). Up to 38% of infections present in patients with malignancy emphasizing the importance of microbiological and pathological diagnosis(5). Our case was obscure as biopsies were initially negative and malignancy was diagnosed after antibiotic failure. Despite diagnosis of Actinomycosis, diligent evaluation for malignancy and close follow up are necessary.