The Korean Journal of Internal Medicine : 22:215-219, 2007 Mycobacterium Avium Complex Infection Presenting as an Endobronchial Mass in a Patient with Acquired Immune Deficiency Syndrome Ho Cheol Kim, M.D., In-Gyu Bae, M.D., Jeong Eun Ma, M.D., Jong Shil Lee, M.D.2, Kyoung-Nyeo Jeon, M.D.3, Jong Deok Lee, M.D. and Young Sil Hwang, M.D. Departments of Internal Medicine, Pathology2 and Diagnostic Radiology3, College of Medicine, Gyeongsang National University, Jinju, Korea Mycobacterium avium complex (MAC) infection is a common opportunistic infection in patients with AIDS (acquired immune deficiency syndrome). Pulmonary involvement of MAC may range from asymptomatic colonization of the respiratory tract to invasive parenchymal or cavitary disease. However, endobronchial lesions with MAC infection are rare in immunocompetent and immunosuppressed hosts. Here, we report MAC infection presenting as an endobronchial mass in a patient with AIDS. Key Words : Mycobacterium avium complex, Endobronchial mass, AIDS INTRODUCTION Mycobacterium avium complex (MAC) is well-known as a common opportunistic organism in patients infected with the human immunodeficiency virus (HIV)1). MAC also acts as a pulmonary pathogen in immunocompetent patients with underlying structural lung diseases such as chronic obstructive pulmonary disease (COPD) and bronchiectasis, as well as in destructive lung lesions like those observed previously in diagnosed tuberculosis2). Pulmonary involvement of MAC may range from airway colonization to invasive parenchymal disease. Pulmonary parenchymal disease with MAC occurs rarely in patients with HIV in the absence of dissemination3). Endobronchial involvement due to M. tuberculosis is a well- described and a relatively common manifestation of tuberculosis in the Republic of Korea4). However, endobronchial lesions involved in MAC infection are rarely found in immunocompetent and immunosuppressed hosts5, 6). There have been few reports of an endobronchial presentation of MAC infection in patients with acquired immune deficiency syndrome (AIDS)6-11). Here, we report an MAC infection presenting as an endobronchial mass in a patient with AIDS receiving anti-retroviral chemotherapy. CASE REPORT A 40-year-old male was admitted to the hospital because of cough with sputum lasting for seven days. He was known to be HIV-positive from a diagnosis made eight months previously. Five months prior to admission, he was diagnosed with Pneumo- cystis carinii (P. carinii) pneumonia (PCP), cytomegalovirus (CMV) pneumonia, and herpes zoster infection on the skin. He was then started on lamivudine, zidovudine, and indinavir as anti-retroviral therapy and trimethoprim/sulfamethoxazole as PCP prophylaxis. At that time, his CD4 and CD8 lymphocyte counts were 356/mm3 and 1546/mm3, respectively, and his CD4/CD8 ratio was 0.23. His HIV viral load (measured by Roche Amplicor RT-PCR) was 670,000 copies/mL. Seven days ∙Received : November 3, 2006 ∙Accepted : December 7, 2006 ∙Correspondence to : Ho Cheol Kim, M.D. Department of Internal Medicine, College of Medicine, Gyeongsang National University. 92 Chilam-dong, Jinju 660-751, Korea Tel : 82-55-750-8684, Fax : 82-55-758-9122, E-mail : hochkim@gshp.gsnu.ac.kr