langerhans ' cell histiocytosis ( lch ) is a proliferative disease characterized by monoclonal proliferation and the infiltration of organs with langerhans ' cells . several organ systems may be involved in lch including the lungs , bone , skin , pituitary gland , liver , lymph nodes , and thyroid . localized forms of lch in bone have been referred to as eosinophilic granuloma since lichtenstein first described them in 1940 . the term " pulmonary langerhans ' cell histiocytosis ( plch ) " was first coined by farinacci in 1951   and refers to disease in adults that affects the lungs , either in isolation or in addition to other organ systems . multi - systemic variants of this disease are known by a variety of names , including systemic histiocytosis x , letterer - siwe disease , and hand - schuller - christian disease . to avoid confusion , the histiocyte society has established a simplified classification system . according to this system , plch is a disease in adults that affects the lungs , either in isolation or in addition to other organ systems . the most common findings on high - resolution computed tomography ( hrct ) of the chest are multiple nodular and cystic changes , which occur predominantly in the middle and upper lobes . nodular lesions are predominant in the early stage of plch and progress to cystic lesions in later stages of the disease . in korea , multiple cystic lesions are the main radiological findings of plch , and no cases with multiple nodular lesions without cysts have been reported . here , we report a case of plch with multiple nodules without cysts throughout the lungs . a 31-year - old male was admitted to our hospital for a cough and exertional dyspnea , which had been present for 2 months . he had no hypertension , tuberculosis , or diabetes , and no history of surgery , medication , or travel . his vital signs were blood pressure 120/80 mmhg , pulse 84/minites , respiration rate 20/minites , and body temperature 37.2. physical examination of the head and neck revealed no palpable cervical lymph nodes or masses and no neck vein engorgement . auscultation of the chest revealed a regular heart beat with no murmurs and clear breath sounds with no crackles or wheezing . laboratory examination indicated a white blood count of 10,310/mm , hemoglobin concentration of 16.0 g / dl , and platelet count of 202,000/l , and the chemistry was unremarkable . arterial blood gas analysis revealed a ph of 7.455 , pao2 99.1 mmhg , paco2 38.2 mmhg , hco3 27 mmol / l , and 98% o2 saturation . the results of the pulmonary function test were forced vital capacity ( fvc ) 5.46 l / minites ( 105% of predicted ) , forced expiratory volume in 1 second ( fev1 ) 4.59 l / minites ( 110% of predicted ) , and fev1/fvc 84% . we performed fiber optic bronchoscopy for bronchoalveolar lavage and observed no abnormal findings in the gram stain or culture , acid - fast bacillus stain or culture , tuberculosis - pcr , or cytology . the chest ct revealed variable - sized nodules with peribronchiolar or centrilobular distribution , some of which revealed thick - walled cavitary change ( fig . the differential diagnosis based on the chest ct findings was that the pulmonary nodules represented hematogenous metastasis . histologically , multiple nodules showed an infiltration of eosinophils , lymphocytes , and langerhans ' cells ( fig . treatment consisted only of smoking cessation , and a chest radiograph 4 months later indicated that the nodules had decreased in size . after 15 months , we observed that the symptoms had improved further , and a follow - up chest radiograph and hrct indicated that the multiple nodules had disappeared ( fig . this case involved a young male who currently smoked and had multiple pulmonary nodules , which were suspicious of metastasis . plch is a rare disorder found in only 5% of biopsy - confirmed interstitial lung disease . reviewed 102 cases with histopathologically confirmed plch drawn from a group with a mean age of 40.3 years and a 1 : 1.5 ratio of males to females and found that 95% of the cases involved smokers . the only consistent epidemiologic association is cigarette smoking , which is involved in the overwhelming majority ( > 90% ) of cases . several hypotheses have been proposed to explain the association between cigarette smoking and plch . according to one , cigarette smoke induces the secretion of bombesin - like peptides from neuroendocrine cells in the lungs . these peptides may have an important role in mediating lung injury and consequently induce lung fibrosis . other components of cigarette smoke , such as tobacco glycoprotein , have also been implicated in the pathogenesis of plch . nevertheless , plch occurs in a very small percentage of smokers , so genetic or environmental factors likely contribute to the development of this disease . a young male who currently smoked complained of a cough and exertional dyspnea , common clinical features of plch ; however , the radiological findings did not support a diagnosis of plch . hrct of the chest is a useful , sensitive tool in the diagnosis of plch . the combination of diffuse , irregularly shaped cystic spaces with small peribronchiolar nodular opacities , predominantly in the middle and upper lobes , is highly suggestive of plch [ 6 - 8,13 ] . when these features are present on hrct , they allow the clinician to make a diagnosis of plch without a lung biopsy . the lung cysts of plch are often less than 20 mm in diameter and typically have thin walls ( < 1 mm ) [ 6 - 8 ] . the frequency of cystic change reflects the timing of imaging during the course of the disease [ 1,6 - 8 ] . in the early stages , the most common finding is nodular change , whereas in the later stages , cystic change and fibrosis predominate [ 6 - 8 ] . based on the radiological staging , this case represents an early stage of plch comprised of nodular lesions only without cystic change . this finding is rare ; only one other case of plch with multiple cavitating pulmonary nodules has been reported , although several cases of plch presenting as a solitary pulmonary nodule have been reported worldwide . none of these cases progressed to a more severe stage , such as cystic change or reduced pulmonary function . brauner et al .   reported two cases of plch in which only nodules were present : one progressed to cystic change and the nodular lesion disappeared in the other . it is thought that predominantly nodular lesions in plch appear early in the reversible state of the disease . in korea , a number of cases of plch have been reported based on variable radiological findings , including multiple cysts and a combination of nodules and cysts . however , no case involving only nodular lesions has been reported . atypical radiological findings as in this case need to be followed to determine whether sarcoidosis , pneumoconiosis , military tuberculosis , hypersensitivity pneumonitis , or metastatic lung nodules are present . the confirmative diagnostic tool is a pathological examination of a lung biopsy . in this case , an open lung biopsy was performed , which resulted in the diagnosis of plch based on positive staining for s-100 protein . the only treatment was smoking cessation , and clinical and radiological improvement was observed 15 months later . here , we report a case of early stage plch in a young male that had atypical radiological features , which consisted of variable - sized nodules only without cystic changes .
a 31-year - old man presented with a dry cough and exertional dyspnea . 
 the chest x - ray showed multiple nodular opacities throughout the entire lung field . 
 chest computed tomography ( ct ) revealed variable - sized nodules with a peribronchiolar or centrilobular distribution , some of which revealed thick - walled cavitary change . based on the chest ct findings , it was initially assumed that metastatic lung nodules with hematogenous spread were present ; therefore , we performed an open lung biopsy . on microscopic examination , 
 several compact cellular interstitial infiltrates composed of langerhans ' cells , eosinophils , and lymphocytes were observed . 
 immunochemically , the langerhans ' cells showed strong cytoplasmic staining for s-100 protein . 
 based on these findings , the patient was diagnosed with langerhans ' cell histiocytosis of the lung . 
 high - resolution ct of the chest is a useful , sensitive tool in the diagnosis of pulmonary langerhans ' cell histiocytosis ( plch ) . 
 a typical radiologic finding of plch is irregularly shaped cysts . 
 the radiological finding in this case of nodular opacities throughout the lung fields only without cysts is rare in plch . 
 we report a case of plch with atypical multiple nodules mimicking hematogenous metastatic lung nodules .