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pulmonary alveolar microlithiasis ( pam ) is a rare and chronic lung disease , characterized by the presence of small round bodies containing concentric calcareous lamellas in pulmonary alveoli ( 1 - 3 ) .
the disease could remain asymptomatic for decades , with subsequent occurrence of dyspnea , chest pain , and dry cough , and could result in respiratory failure ( 3 ) . half of the patients were asymptomatic at the time of diagnosis ; therefore , most reported cases were diagnosed during a routine examination ( 1 - 3 ) .
characteristic radiologic findings consist of bilateral innumerous calcified nodules , which might suggest the disease , and it is subsequently confirmed with a less invasive procedure , such as bronchoscopy ( 4 ) .
most cases of pam in asia have been reported in turkey , india , and japan ( 1 - 3 ) .
here we reported on the first case of pam in korea , confirmed by open lung biopsy .
a 19-yr - old male exhibiting no respiratory symptoms visited our hospital on november 9 , 2010 for evaluation of abnormalities noted on a chest radiogram of a routine health check for military service .
he had eight elder sisters , but no family history disclosing pulmonary disease . on admission ,
the patient had evidenced no abnormal physical findings , and laboratory data were also normal .
results of the pulmonary function test were also normal ; an fvc of 4.48 liters ( 115% predicted ) , a normal fev1 of 3.83 liters ( 107% predicted ) , and a fev1/fvc ratio of 85% .
diffusion capacity study showed a dlco of 33.4 ml / mmhg / min ( 126% predicted ) .
a chest radiogram taken on the day of his visit showed bilateral , diffuse , fine reticulonodular opacities in both lungs ( fig .
high resolution ct ( hrct ) scan revealed scattered micronodules , interlobular septal thickening , subpleural interstitial thickening , and some areas of ground - glass opacity .
subpleural cystic changes and microcalcifications along the subpleural regions and some interlobar septa were also observed ( fig .
cell analysis of bronchoalveoloar lavage ( bal ) fluid showed 80% in lymphocytes and 15% in monocytes .
histological findings of vats biopsy showed multiple round small calcified nodules in the visceral pleura and the alveolar wall , consistent with the diagnosis of pam ( fig .
the patient was followed up in out - patient clinic for 6 months without progression of the disease and had no treatment for pam .
pam is a rare disease and has been reported with no particular geographic or racial distribution ; however , europe is the most prevalent area , followed by asia , particularly turkey , india , and japan ( 1 , 2 ) .
a genetic factor has been supposed because of familial occurrence ( 1 , 2 ) .
recently , a mutation in the scl34a2 gene , which encodes a type iib sodium dependent phosphate transporter , was suggested as a pathogenesis of this disease ( 5 ) .
cl34a2 is primarily expressed in alveolar type ii cells responsible for surfactant production using phospholipids and plays a major role in homeostasis of inorganic phosphate ( 5 ) .
therefore , dysfunction in cl34a2 can result in accumulation of phosphorus ion in alveolar space and is likely the cause of pam . in this case
, none of the family members of the patient had experienced any type of respiratory illness .
there was no sex difference in the rate of occurrence in reported cases and it was most frequently discovered from birth up to 40 yr of age ( 1 - 3 ) . due to the inability to certify clear etiological and pathogenic factors ,
a therapeutic approach is difficult , and there is currently no effective medical treatment for this disease and affected individuals may progress to respiratory failure .
therefore , lung transplantation should be considered in end stage pam , where either severe respiratory failure or right heart failure is present ( 6 - 8 ) .
therefore , in many cases , the diagnosis is made as an incidental radiographic film in symptomless patients ( 3 ) .
the chest radiograph usually revealed small innumerable , widespread , and calcified nodules , which tend to be greatest at the base ( 4 , 9 , 10 ) .
hrct scan has aided in characterization of the imaging of the disease and can be useful in diagnosis ( 4 , 9 , 10 ) .
ground - glass opacities due to volume averaging of tiny microliths are a common and major finding in the literature ( 4 , 9 , 10 ) .
subpleural linear calcification and nodular fissural thickening are also a common finding ( 4 , 9 , 10 ) . in this case , these findings were also observed on his chest ct .
although specific findings in hrct scan could lead to diagnosis of pam , other cases of diffuse pulmonary calcification should be considered for differential diagnosis , including metastatic pulmonary calcification , amyloidosis , and dendriform pulmonary ossification ( 11 ) .
however , clinician 's awareness of typical hrct findings of this disease could lead to diagnosis using less invasive procedures .
therefore , most recently reported cases of pam were diagnosed by transbronchial biopsy and bal ( 1 ) . in this case ,
due to lack of experience with this disease , we performed open lung biopsy for diagnosis . in conclusion , pam is a rare disease that can present with no symptoms .
pulmonary alveolar microlithiasis ( pam ) is a rare disease with unknown etiology and pathogenesis . 
 it is characterized by diffuse , innumerable , and minute calculi , called microlithiasis in the alveoli . 
 more than half of reported cases are asymptomatic at the time of diagnosis . 
 we describe the first case of pam in korea . a 19-yr - old man without respiratory symptoms presented with interstitial thickening on the chest radiograph . 
 his chest high resolution ct scan showed diffusely scattered , ill defined tiny micronodules and interstitial thickening . 
 open lung biopsy confirmed the diagnosis of pam . 
 he was followed up for 6 months without treatment , and no progression was noticed .