dilatation of pulmonary arteries is a well - known clinical entity commonly encountered in many congenital and acquired heart lesions . idiopathic dilatation of pulmonary arteries ( idpa ) was first recognized as a benign anomaly in 1923 by wessler and jaches . the incidence of this disease is 6 cases per 1000 cases of congenital cardiac disorders . diagnosis of idpa is made after excluding all possible causes that can induce pulmonary artery ( pa ) dilatation . it is usually an incidental finding not fully explained by the patient symptoms and clinical condition . treatment is usually not required as it is considered to be a benign condition , although literature on long - term follow - up is lacking . a 68-year - old female presented with insidious onset gradually progressive shortness of breath from mmrc stage 1 to stage 3 for the last 10 years , which further increased over the past 2 months . she had no associated history of a cough , fever , palpitations , chest pain , pedal edema , orthopnea , or paroxysmal nocturnal dyspnea . on clinical examination , her vitals included pulse rate there was no pallor , icterus , cyanosis , pedal edema , or raised jugular venous pressure . 5600/dl with a differential count of neutrophils  72% , lymphocytes  10% , eosinophils  1% , and monocytes  7% . serum c - reactive protein level was normal ( 0.24 mg / dl ) with elevated serum brain natriuretic peptide levels ( 162 pg / ml ) . anti - nuclear antibodies along with anti - neutrophil cytoplasmic autoantibody levels and thyroid function tests were within normal limit , and there was no evidence of infectious diseases such as tuberculosis or syphilis . x - ray chest revealed mild cardiomegaly of the right ventricular ( rv ) type with mild right atrial dilatation and massive enlargement of the main pa with normal pulmonary vascular markings [ figure 1 ] . ( a ) chest x - ray showing dilated pulmonary artery , ( b ) contrast - enhanced computed tomography chest showing enlarged main pulmonary artery ( 49.75 mm ) , ( c ) contrast - enhanced computed tomography chest showing dilated left pulmonary artery ( 36.96 ) , ( d ) contrast - enhanced computed tomography chest showing dilated right pulmonary artery ( 37.76 mm ) , ( e ) contrast - enhanced computed tomography showing no evidence of pulmonary embolism , ( f ) computed tomography pulmonary artery reconstruction image showing dilated pulmonary artery echo - cardio - graphic findings revealed a normal - sized left ventricle and left atrium with 55% ejection fraction . rv was dilated with adequate systolic function , with dilated right atrium , mild tricuspid regurgitation , and mild pa hypertension ( mean pa pressure 36 mmhg ) . a computed tomography ( ct ) pulmonary angiography with high - resolution ct was done [ figures 1 and 2 ] which revealed dilated main pa with a maximum diameter of 49.75 mm , dilated right main trunk with a diameter of 37.76 mm , and dilated left trunk with a diameter of 36.96 mm . pulmonary function test revealed restrictive airway defect with a normal diffusing capacity of carbon monoxide . she was made to walk for 6 min in which she covered 216 meters without desaturation but had moderate fatigue and severe breathlessness at the end of the test . high - resolution computed tomography sections of lung showing ground glass opacities in lung parenchyma cardiac catheterization was done through right femoral vein / right femoral artery approach . rv angiogram showed the adequate systolic function of rv with normal pulmonary valve and massively dilated the main pa . results of right heart catheterization on the basis of mild symptoms and pulmonary artery pressure ( pap ) < 30 mmhg , a massive dilation of pa could not be explained so the diagnosis of idpa was made after ruling out all possible causes . kaplan et al . postulated it as mal - development of the entire pulmonary tree and congenital weakness of the arterial wall whereas assman thought of it as an unequal division of truncus arteriosus communis . in 1949 , greene et al . and associates established the following pathologic criteria for its diagnosis : 
 simple dilatation of the pulmonary trunk with or without involvement of the rest of arterial treeabsence of intra - cardiac or extracardiac shuntsabsence of chronic cardiac or pulmonary diseaseabsence of arterial disease , such as syphilis , or more than minimal atheromatosis or arteriosclerosis of the pulmonary vascular tree . simple dilatation of the pulmonary trunk with or without involvement of the rest of arterial tree absence of intra - cardiac or extracardiac shunts absence of chronic cardiac or pulmonary disease absence of arterial disease , such as syphilis , or more than minimal atheromatosis or arteriosclerosis of the pulmonary vascular tree . in 1960 , deshmukh et al . , presented report of 13 patients in whom right heart catheterization was performed aimed at elaborating its clinical and physiological aspects and to further draw attention to this anomaly . they opined that normal pressure in the rv and pa should be introduced as the fifth criteria in the diagnosis . our case showed massive dilatation of pa with no apparent intra- or extra - cardiac shunt or any significant heart or lung disease . on right heart catheterization , pap was only 28 mmhg which does not explain the massive dilatation of pa in our case thus confirming the diagnosis . in spite of the well - marked clinical , radiologic and electrocardiographic features , the absence of shunt , the normal relationship in cardiac chambers and normal oxygen saturation are important findings . long - term prognosis of idpa is usually excellent compared to pathological dilatation of pa . however not much data on long - term follow - up of these patients exist . management is also not well established , and any patient with an apparent diagnosis of idiopathic pulmonary hypertension needs to be followed up for a long time to know its benign course . our case adds to the existing literature and spreads physician awareness about this entity and its diagnosis , which should be established after ruling out all possible causes of pulmonary dilatation .