nontuberculous mycobacteria ( ntm ) have emerged as an increasingly important pathogen in the last two decades . unlike other environmental pathogens that are largely opportunistic in patients with malignancy and immunodeficiency , as well as transplant recipients , ntm can cause significant disease in otherwise healthy individuals . the ntm most commonly associated with pulmonary infection is the mycobacterium avium complex ( mac ) , which is a microbial complex of mycobacterium avium and mycobacterium intracellulare . there have been many reports concerning its radiologic findings.123 ) although uncommon , several cases of solitary pulmonary nodules ( spn ) caused by mac pulmonary infections have been reported,456 ) which is different from the typical presentation of mac . however , a case of a multiple cavitating nodular infection with neither a fibrotic change nor nodular bronchiectasis associated with m. intracellulare has not been reported . we present the case of a 67-year - old asian woman who had a m. intracellulare infection presenting with multiple cavitating pulmonary nodules , which was differentiated from metastatic lung disease by percutaneous transthoracic needle aspiration ( pcna ) . she presented to a local clinic after a single occurrence of hemoptysis 10 days prior . the color of the hemoptysis was scarlet and the amount was 1/2 cup of soju , korean distilled spirits . she had been diagnosed with type 2 diabetes mellitus ( dm ) 2 years prior at a local clinic , and had since been taking metformin 500 mg after breakfast and dinner . glycosylated hemoglobin was 6.7% , and she had good control of her blood sugar levels during hospitalization . after a chest ct was obtained at the local clinic , she was transferred to our hospital to investigate the multiple cavitary pulmonary nodules that were found on the ct scan . when the patient visited our hospital , her initial vital signs showed a blood pressure of 110/70 mm hg , heart rate of 80 beats / min , respiratory rate of 16 breaths / min , and body temperature of 36.8. both pupil responses to light were normal and there was no abnormality in the conjunctivae and sclerae . on auscultation , neither crackles nor wheezing was heard in both lung fields , and the heart sound was regular without murmur . at the first visit to our hospital , the patient did not have any symptoms . there were several round nodules in both the upper lung zone and right middle lung zone , and patch consolidation in the left lower lung zone on the chest radiography , which is suggestive of mycobacterium tuberculosis ( mtb ) or metastatic lung disease ( figure 1 ) . similarly , the chest ct showed centrilobular nodules with a tree - in - bud appearance and three round cavitary nodules in the left apex , the right upper lobe posterior segment , and the right lower lobe superior segment , suggestive of mtb or metastatic lung disease ( figure 2 ) . we isolated the patient because we could not exclude the possibility of mtb along with metastatic lung disease . the initial laboratory parameters were as follows : total leukocyte count 7,500/mm ( neutrophil 64.6% , lymphocyte 21.1% , monocyte 0.44% ) ; hemoglobin level 12.8 g / dl ; and platelet count 217,000/mm . the level of c - reactive protein was 0.03 mg / dl and other parameters were within the normal limit on the blood chemistry tests . additionally , the coagulation profile was checked , and the prothrombin time was 11.1 seconds ( international normalized ratio 1.35 ) . for further evaluation , we planned to perform a bronchoscopy and pcna , and the additional imaging examinations were not performed because chest imaging was obtained on the day of the initial hospital visit . the results of three smears for acid - fast bacilli , and a nucleic acid amplification test for mtb and ntm in sputum were all negative . for further evaluation , a bronchoscopy was performed on the left upper lobe apical segmental bronchus , the right upper lobe posterior segmental bronchus , and the right lower lobe superior segmental bronchus . the smear test of the bronchoscopic washing fluid was positive for acid - fast bacilli . the result of nucleic acid amplification was negative for mtb , but positive for ntm . therefore , the patient was diagnosed with ntm , so the patient 's quarantine was lifted . after 7 days , heavy colonies with confluent growth in ogawa 's egg medium were detected in the bronchial washing fluid culture . after 2 weeks , several colonies with confluent growth in the mycobacterium growth indicator tube 's egg medium were detected in the bronchial washing fluid culture . the precise species was identified using a polymerase chain reaction - restriction fragment length polymorphism - based method that identified differences in the rpob gene.7 ) the colonies were subsequently identified as m. intracellulare . to rule out metastatic lung disease , the lung tissue from the biospy showed chronic granulomatous inflammation with caseating necrosis ( figure 3a , b ) . for further evaluation , a nucleic acid amplification for mtb and ntm with a stain for acid - fast bacilli was conducted using tissue from the pcna . the additional report showed that both the nucleic acid amplication for ntm and the stain for acid - fast bacilli were positive ( figure 3c ) , and there were no malignant cells . this finding was consistent with ntm infection , and we could exclude metastatic lung disease . in conclusion , the lung tissue from the biospy confirmed the diagnosis obtained from the bronchial washing fluid culture . with the diagnosis of ntm infection the patient was prescribed a medication regimen that included rifampin ( 450 mg ) , ethambutol ( 800 mg ) , and clarithromycin ( 1,000 mg ) . a drug susceptibility test for clarithromycin was performed , and the result showed that the m. intracellulare was sensitive to clarithromycin . the patient started to complain of nausea and vomiting , and had poor oral intake 7 days after taking the medication for ntm . we changed the time for taking the medication from before meals to before bed , after which her symptoms improved . there were no other complications such as an abnormal liver function test or optic neuritis . we have performed blood tests and chest radiography to monitor the side effects and the disease progression . m. avium is the more important pathogen in a disseminated disease , whereas m. intracellulare is the more common respiratory pathogen . the chest radiography and ct scans showed abnormalities typical of the two forms of mac lung disease . the traditionally recognized presentation of mac lung disease is as an apical fibrocavitary lung disease with large cavities , located in the upper lobe . this form of the disease usually occurs in men with a history of cigarette smoking , excessive alcohol use , and underlying lung disease in their late 40s and early 50s . if not treated , this form of mac is rapidly progressive within a relatively short time period , 1 to 2 years mac lung disease also presents with bronchiectatic nodular infiltrates , usually involving the right middle lobe or the lingula segment , predominantly in postmenopausal and non - smoking women . this form of the disease has a tendency to progress much slower than the fibrocavitary disease , therefore long - term follow - ups lasting from months to years may be necessary to determine clinical or radiographic changes . in this indolent form of the disease spn is identified as focal , round , or oval areas of increased opacity in the lung that measure 3 cm in diameter . these nodules are frequently discovered incidently on chest radiography or chest ct.8 ) spn is often assumed to be attributable to mtb infection.9 ) however , it has been shown in case reports that spn can be attributable to mac lung infection.456 ) in 2009 , sekine et al.10 ) reported a case of a mac pulmonary infection presenting with multiple nodules , which was an unusual presentation of a mac pulmonary infection . unlike mtb therefore , the isolation of mac species from a respiratory sample is not sufficient evidence of ntm lung disease . in 1997 , the american thoracic society issued a revised set of diagnostic criteria for ntm pulmonary disease . according to these criteria , a patient with ntm lung disease must have compatible symptoms and signs , and a compatible chest radiography or chest ct abnormalities . the current case did not strictly satisfy the diagnostic criteria proposed by the american thoracic society in terms of radiographic findings . the diagnostic criteria of ntm lung disease must be expanded to such cases of spn , multiple nodules , and multiple cavitary nodules , as in our case . in our case , we could not initially rule out mtb lung infection due to the chest ct findings , which showed multiple cavitating nodules with centrinodular nodules . we did not suspect mac lung infection because there was neither bronchiectasis in the right upper lobe or the left lingular segment nor a fibrotic change in the upper lobe . while the bronchoscopy findings were sufficient to diagnose the patient with mac lung infection , we also conducted a pcna to rule out metastatic lung disease . , we differentiated the atypical presentation of mac lung infection from mtb lung disease or metastatic lung disease . ntm have emerged as an increasingly important pathogen in the last two decades . in korea , there has been an increasing prevalence of mac infections , and an increasing number of cases presenting with atypical findings . our case report highlights the importance of differentiating among mtb , mac infection , and metastatic lung disease in cases of multiple cavitary nodules . clinicians should consider the possibility of mac lung infection with various findings on chest radiography and chest ct . we believe that pcna can be a valuable diagnostic tool for differentiating mtb and mac , and differentiating between malignant diseases and infectious diseases when a pulmonary nodule is revealed on chest radiography or chest ct scans . in conclusion , to the best of our knowledge , this is a very rare report of a mac pulmonary infection presenting with multiple cavitary nodules . as the prevalence of mac infections increases , more cases start to show atypical radiographic findings , compared to the typical apical fibrocavitary or bronchiectatic nodular forms . other forms of mac have been reported , such as spn and multiple nodules . in this report , we present another form of mac pulmonary infection . therefore , clinicians should consider the possibility of mac lung disease with various findings on chest radiography or chest ct scans . in addition , pcna can be a useful diagnostic tool for evaluating multiple nodules to differentiate metastatic lung diseases from infectious diseases such as mtb or mac lung infections .
nontuberculous mycobacteria ( ntm ) have been increasingly recognized as an important cause of chronic pulmonary infections . 
 the mycobacterium avium complex ( mac ) , which is composed of two species , mycobacterium avium and mycobacterium intracelluare , is the most commonly encountered pathogen associated with ntm lung disease . mac pulmonary infection typically presents in a fibrocavitary form or a nodular bronchiectatic form . 
 however , there have been atypical presentations of mac pulmonary infections , including solitary pulmonary nodules ( spn ) . 
 there have been several previous reports of spn due to mac infection in the united states , japan , and korea . in 2009 , 
 sekine and colleagues reported a case of mac pulmonary infection presenting with multiple nodules . to date , however , there have been no cases of ntm lung infection with multiple cavitary pulmonary nodules , and neither a fibrotic change nor nodular bronchiectasis . 
 the present case showed a multiple cavitating nodular lung infection due to mac , which is very rare and different from the typical presentation of mac pulmonary infections . 
 we also showed that percutaneous transthoracic needle aspiration can be a useful diagnostic tool to evaluate a case of multiple cavitary nodules .