We report a ease of extensive mediastinal lymphadenopathy in a 29-year-old immunocompetent woman, which was thought to be caused by Mycobacterium tuberculosis (MTB). Chest radiographs showed deterioration while the patient was receiving antituberculous medication for 8 months. After isolation of Mycobacterium avium complex (MAC) from a lymph node aspiration biopsy and switch to a MAC-specific therapeutic regimen, the lesion almost completely disappeared within 1 year. To our knowledge, this is the first report of an extensive mediastinal lymphadenopathy caused by MAC in an immunocompetent adult.
(CHEST 1999; 116:1814-1816)
Key words: immunocompetence; mediastinal lymphadenopathy; Mycobacterium avium complex; Mycobacterium tuberculosis; nontuberculous mycobacteria
Abbreviations: MAC = Mycobacterium avium complex; MTB = Mycobacterium tuberculosis; NTM = nontuberculous mycobacteria; TB = tuberculosis
Besides pulmonary disease, lymphadenopathies are the most frequent manifestations of mycobacterial infections.[1] An enlargement of the mediastinal lymph nodes in the course of an infection with Mycobacterium tuberculosis (MTB) can be diagnosed quite frequently,[2,3] but to our knowledge, there is no description of mediastinal lymphadenitis caused by nontuberculous mycobacteria (NTM) in an immunocompetent adult. Even in children, this location of NTM disease is extremely rare.[4,5] We report a case of a 29-year-old nurse from Turkey with a huge mediastinal mass and the diagnosis of Mycobacterium avium complex (MAC) disease.
CASE REPORT
A mediastinal mass was demonstrated on chest radiograph in a 29-year-old Turkish woman, and histopathologic examination of a supraclavicular lymph node diagnosed tuberculosis (TB) in May 1996. There was no proof by culture. For reasons of pregnancy, therapy was not initiated until September 1996, when isoniazid, 300 mg qd, and ethambutol, 20 mg/kg of body weight, was administered for 2 months until delivery. Then, a therapy of isoniazid; rifampicin, 600 mg; ethambutol; and streptomycin, 1 g 5 days a week for 6 weeks, was begun; after 4 more months, a chest radiograph did not reveal any change for the better. There was no evidence of noncompliance on the part of the patient. In March 1997, mediastinoscopy was performed, and histopathologic examination of the lymph node specimen showed typical features of active TB. Microbiological analysis of biopsy material identified acid-fast bacilli, but culture results were negative.
The patient presented at our institution in April 1997 complaining of cough and chest pain on deep inspiration, with no weight loss and no night sweats. The physical examination showed no abnormalities; laboratory analysis revealed an elevated erythrocyte sedimentation rate, an elevated C-reactive protein, and mild anemia. A skin test for recall antigens (Multitest-Merieux; Pasteur Merieux; Leimen, Germany) showed a positive reaction to tuberculin only. No antibodies against HIV-1 or HIV-2 were detected. Further analysis did not reveal abnormalities of humoral or cellular immunity. Chest radiographs showing the increasing size of a right-sided mediastinal mass, and imaging of the lesion by CT of the chest are shown in Figures 1-3. By ultrasound scanning of the neck, a retroclavicular lymph node of 2 cm in diameter was detected, of which a needle aspiration biopsy was done twice. Nucleic acid amplification test results for MTB complex were negative, but cultures from both specimens were positive for MAC. A chest radiograph of June 1997 showed additional pulmonary infiltration of the right upper lobe. Bronchoscopy and transbronchial biopsies as well as transtracheal needle aspiration biopsies were performed. For both sites, abortive granuloma without acid-fast bacilli were described histopathologically (Fig 4). Nucleic acid amplification test results of biopsy specimens and sputum samples were negative for MTB complex; in addition, cultures failed to detect mycobacteria. Polymerase chain reaction from a paraffin-fixed histologic specimen gained by mediastinoscopy in March 1997 has been performed, but no mycobacterial DNA sequence could be detected.
[Figures 1-4 ILLUSTRATION OMITTED]
Sensitivity testing of the M avium strain showed resistance to all first-line drugs. After the results of combination testing were analyzed, therapy with rifabutin, 300 mg qd; clarithromycin, 500 mg bid; and prothionamide, the N-propyl derivative of ethionamide, 500 mg bid (later substituted by ethambutol), was introduced. After 6 weeks of modified treatment, chest radiograph showed marked improvement, and the size of the mediastinal mass as well as that of the pulmonary nodule decreased continuously (Fig 5). Clinical symptoms had already disappeared in October 1997, and therapy had been stopped in October 1998. Corticosteroids have never been prescribed for the patient.
[Figure 5 ILLUSTRATION OMITTED]
DISCUSSION
We report a case of mycobacterial mediastinal lymphadenopathy caused by an infection with MAC in an immunocompetent, HIV-seronegative Turkish woman, a setting that, to our knowledge, has not been published before. The main differential diagnosis of course is infection by MTB, which usually is thought to cause mediastinal lymphadenopathy, revealing typical findings in chest CT and histologic examination of biopsy specimens. As our patient had a positive tuberculin skin test result, the diagnosis of TB seemed rather convincing.
But there are several aspects pointing to another etiologic agent, namely MAC:
* MTB has never been isolated, and we have not been successful in demonstrating DNA of MTB in any specimen.
* MAC has been isolated twice from needle-aspiration specimens of an enlarged retroclavicular lymph node.
* Lymphadenopathy by MTB is described to respond to antituberculous therapy very well, and even short course therapy is recommended,[6] but our patient has been treated for about 8 months for TB and at least for 6 months using regimens containing isoniazid and rifampicin without any improvement.
* Already 6 weeks after the initiation of therapy with rifabutin, clarithromycin, and protionamide (later ethambutol), regression of the mediastinal mass could be described.
* After 6 months of antituberculous therapy, a nodular lesion persisted in the upper lobe of the right lung, pointing to a nontuberculous etiology. As pulmonary biopsy revealed abortive granuloma, there is good reason to believe in mycobacteria as the inducing pathogen. Pulmonary lesions disappeared after therapy for MAC disease.
CONCLUSION
In otherwise healthy adults, MAC (and maybe other NTM) may cause lymphadenopathies of the mediastinum, a site of disease being more typical for infections by MTB. In lymphadenopathy at any site that shows typical histopathologic features of TB and does not adequately respond to antituberculous therapy, NTM should be thought of as the etiologic agent. Before initiating antituberculous or other antimycobacterial therapy, definitive attempts should be made to establish a bacteriologic diagnosis.
REFERENCES
[1] Wolinsky E. Nontuberculous mycobacteria and associated diseases. Am Rev Respir Dis 1979; 119:107-159
[2] Baran R, Tor M, Tahaoglu K, et al. Intrathoracic tuberculous lymphadenopathy: clinical and bronchoscopic features in 17 adults without parenchymal lesions. Thorax 1996; 51:87-89
[3] Codecasa LB, Besozzi G, De Cristofaro L, et al. Epidemiological and clinical patterns of intrathoracic lymph node tuberculosis in 60 human immunodeficiency virus-negative adult patients. Monaldi Arch Chest Dis 1998; 53:277-280
[4] Nussbaum E, Hanson GR, Galant S. Nontuberculous mycobacterial infection in an infant with a mediastinal mass. Clin Pediatr 1982; 21:246-247
[5] Fergie JE, Milligan TW, Henderson BM, et al. Intrathoracic Mycobacterium avium complex infection in immunocompetent children: ease report and review. Clin Infect Dis 1997; 24:250-253
[6] Campbell IA, Ormerod LP, Friend JA, et al. Six month versus nine month chemotherapy for tuberculosis of lymph nodes: final results. Respir Med 1993; 87:621-623
Correspondence to: Ulf Greinert, MD, Department of Clinical Medicine, Parkallee 35, Research Center Borstel, D-23845 Borstel, Germany; e-mail: ugreinert@fz-borstel.de
COPYRIGHT 1999 American College of Chest Physicians
COPYRIGHT 2000 Gale Group
