JSTR MEETING NOTES
Imaging of a Case of Disseminated Mycobacterium avium Complex Infection Yuko Nishimoto, MD,*w Naoto Katayama, MD,w Seishu Hashimoto, MD,z Yoshio Taguchi, MD,z Yoichiro Kobashi, MD,y and Satoshi Noma, MDw
Key Words: Disseminated Mycobacterium avium complex infection, HR-CT (high resolution computed CT), FDG-PET
(J Thorac Imaging 2013;28:W123–W125)
N
ontuberculosis mycobacteria, including the Mycobacterium avium complex (MAC), are environmental microorganisms living widely in soil and water. MAC has been increasingly recognized as an infectious agent in immunocompetent patients without preexisting pulmonary disease. MAC infection is usually limited to the lungs. Disseminated MAC refers to the spread to extrapulmonary regions, such as extrathoracic lymph nodes, the osseous system, or other organs. Disseminated MAC disease is very rarely associated with any form of immunosuppression other than advanced human immunodeficiency virus infection. However, dissemination of MAC in adult patients without acquired immunodeficiency syndrome (AIDS) has been reported in immunosuppressed patients with renal or cardiac transplantation, chronic corticosteroid use, and leukemia.1 Recently, several cases of disseminated MAC infection have also been reported in immunocompetent hosts.2,3
nodules in the left lower lobe and a left pleural effusion were also evident (Fig. 2B). There were no cavitary lung nodules or masses. Because malignant lymphoma was suspected on the basis of the results of chest CT, 18F-fluorodeoxy-glucose positron emission tomography (FDG-PET) was performed. FDG-PET showed increased accumulation in the left lung, left subclavian and mediastinal lymph nodes, spleen, and multiple bones (Fig. 3). Due to a high suspicion for malignant lymphoma, bronchoscopy was performed for further diagnostic evaluation. Bronchoscopy showed multiple small polypoid lesions in the trachea (Fig. 4A). Histologic examination of the specimens obtained from the tracheal wall with transbronchial tracheal biopsy showed chronic inflammation, and acid-fast bacilli were detected by ZiehlNeelsen staining (Fig. 4B). MAC was identified with a polymerase chain reaction technique. MAC was also positive in needle biopsy specimen of a left subclavian lymph node and in the peripheral blood culture. Therefore, the patient was diagnosed with disseminated MAC infection.
DISCUSSION Pulmonary disease due to MAC typically manifests in immunocompetent adults as a chronic lung infection with radiographic findings of bronchiectasis, nodules, and/or cavitary lesions. However, MAC may also present as a disseminated disease that occurs almost exclusively in immunocompromised patients, including patients with
CASE REPORT A 49-year-old previously healthy woman was admitted to our hospital because of sustained fever and productive cough after she had been diagnosed with pneumonia and treated with antibiotics for 1 month. Laboratory examination revealed the following data: peripheral leukocyte count of 18,900/mL (normal range, 6000 to 9000/mL), alkaline phosphatase (ALP) level of 723 IU/L (normal range, 110 to 340 IU/L), lactate dehydrogenase (LDH) level of 394 IU/L (normal range, 120 to 242 IU/L), C-reactive protein (CRP) level of 5.9 mg/dL (normal range,
Imaging of a Case of Disseminated Mycobacterium avium Complex Infection Yuko Nishimoto, MD,*w Naoto Katayama, MD,w Seishu Hashimoto, MD,z Yoshio Taguchi, MD,z Yoichiro Kobashi, MD,y and Satoshi Noma, MDw
Key Words: Disseminated Mycobacterium avium complex infection, HR-CT (high resolution computed CT), FDG-PET
(J Thorac Imaging 2013;28:W123–W125)
N
ontuberculosis mycobacteria, including the Mycobacterium avium complex (MAC), are environmental microorganisms living widely in soil and water. MAC has been increasingly recognized as an infectious agent in immunocompetent patients without preexisting pulmonary disease. MAC infection is usually limited to the lungs. Disseminated MAC refers to the spread to extrapulmonary regions, such as extrathoracic lymph nodes, the osseous system, or other organs. Disseminated MAC disease is very rarely associated with any form of immunosuppression other than advanced human immunodeficiency virus infection. However, dissemination of MAC in adult patients without acquired immunodeficiency syndrome (AIDS) has been reported in immunosuppressed patients with renal or cardiac transplantation, chronic corticosteroid use, and leukemia.1 Recently, several cases of disseminated MAC infection have also been reported in immunocompetent hosts.2,3
nodules in the left lower lobe and a left pleural effusion were also evident (Fig. 2B). There were no cavitary lung nodules or masses. Because malignant lymphoma was suspected on the basis of the results of chest CT, 18F-fluorodeoxy-glucose positron emission tomography (FDG-PET) was performed. FDG-PET showed increased accumulation in the left lung, left subclavian and mediastinal lymph nodes, spleen, and multiple bones (Fig. 3). Due to a high suspicion for malignant lymphoma, bronchoscopy was performed for further diagnostic evaluation. Bronchoscopy showed multiple small polypoid lesions in the trachea (Fig. 4A). Histologic examination of the specimens obtained from the tracheal wall with transbronchial tracheal biopsy showed chronic inflammation, and acid-fast bacilli were detected by ZiehlNeelsen staining (Fig. 4B). MAC was identified with a polymerase chain reaction technique. MAC was also positive in needle biopsy specimen of a left subclavian lymph node and in the peripheral blood culture. Therefore, the patient was diagnosed with disseminated MAC infection.
DISCUSSION Pulmonary disease due to MAC typically manifests in immunocompetent adults as a chronic lung infection with radiographic findings of bronchiectasis, nodules, and/or cavitary lesions. However, MAC may also present as a disseminated disease that occurs almost exclusively in immunocompromised patients, including patients with
CASE REPORT A 49-year-old previously healthy woman was admitted to our hospital because of sustained fever and productive cough after she had been diagnosed with pneumonia and treated with antibiotics for 1 month. Laboratory examination revealed the following data: peripheral leukocyte count of 18,900/mL (normal range, 6000 to 9000/mL), alkaline phosphatase (ALP) level of 723 IU/L (normal range, 110 to 340 IU/L), lactate dehydrogenase (LDH) level of 394 IU/L (normal range, 120 to 242 IU/L), C-reactive protein (CRP) level of 5.9 mg/dL (normal range,
