a 57-year - old woman visited the thoracic surgery department of the samsung medical center , seoul , for further evaluation of an abnormal finding on lung examination that had been incidentally detected by routine medical check - up .
she denied any past medical history , and routine physical exams and laboratory tests were within normal limits .
chest computed tomography ( ct ) identified a single 4-mm - sized vascular dilation in the anterior segment of left upper lobe ( fig .
there was no abnormality in the rest of lung parenchyma . under the impression of pavf
cut section of the specimen revealed a 0.5-cm - sized cystic lesion under the pleura .
microscopically , the lesion consisted of irregularly shaped aneurysmal dilation of thick vein ( fig .
additionally , elastic stain showed hypertrophic arteriopathy of pulmonary arterioles around the main aneurysmal vein ( fig .
the patient was discharged without any post - operative complication . a 54-year - old woman presented with incidental abnormal finding on chest x - ray
chest ct revealed a 38-mm - sized large aneurysmal sac in the right middle lobe ( fig .
cut section of the specimen showed a thin - walled cyst with smooth whitish inner surface , measuring 38 mm in diameter ( fig .
elastic stain revealed the lesion to be consisted of aneurysmal dilation of both artery and vein ( fig .
he has had symptoms of cyanosis and clubbing of fingers since he was 4 years old and diagnosed with pavf from chest ct work up .
he showed general cyanosis and complained of dizziness and general weakness , low extremities in particular .
section of the specimen showed many engorged vessels with blood clots mainly in the posterobasal segment , measuring approximately 9 cm in extent ( fig .
he was discharged with no specific postoperative complication . however , diffuse pavfs still remained in other lobes .
he constantly suffered from general weakness and spo2 was still checked as 70% on average .
a 36-year - old man was admitted to the thoracic surgery department for scheduled operation .
although his symptom was relieved , post - treatment chest ct still revealed a multi - cystic lesion in the lateral side of right lung showing plump vascular supply through intercostal arteries or pulmonary arteries ( fig .
it showed no segmental or lobar distribution . under the clinical impression of congenital cystic adenomatoid malformation ( ccam ) ,
cut section of the specimen revealed a multi - lobulated cystic lesion filled with blood , measuring 7 cm in extent ( fig .
microscopic examination revealed that the cystic lining consisted of dilated thick vascular structure ( fig .
the final pathologic diagnosis was given as fistulous arteriovenous malformation / hemangioma ( avmh ) .
a 57-year - old woman visited the thoracic surgery department of the samsung medical center , seoul , for further evaluation of an abnormal finding on lung examination that had been incidentally detected by routine medical check - up .
she denied any past medical history , and routine physical exams and laboratory tests were within normal limits .
chest computed tomography ( ct ) identified a single 4-mm - sized vascular dilation in the anterior segment of left upper lobe ( fig .
there was no abnormality in the rest of lung parenchyma . under the impression of pavf
cut section of the specimen revealed a 0.5-cm - sized cystic lesion under the pleura .
microscopically , the lesion consisted of irregularly shaped aneurysmal dilation of thick vein ( fig .
additionally , elastic stain showed hypertrophic arteriopathy of pulmonary arterioles around the main aneurysmal vein ( fig .
a 54-year - old woman presented with incidental abnormal finding on chest x - ray .
chest ct revealed a 38-mm - sized large aneurysmal sac in the right middle lobe ( fig .
cut section of the specimen showed a thin - walled cyst with smooth whitish inner surface , measuring 38 mm in diameter ( fig .
elastic stain revealed the lesion to be consisted of aneurysmal dilation of both artery and vein ( fig .
he has had symptoms of cyanosis and clubbing of fingers since he was 4 years old and diagnosed with pavf from chest ct work up .
he showed general cyanosis and complained of dizziness and general weakness , low extremities in particular .
cut section of the specimen showed many engorged vessels with blood clots mainly in the posterobasal segment , measuring approximately 9 cm in extent ( fig .
he constantly suffered from general weakness and spo2 was still checked as 70% on average .
a 36-year - old man was admitted to the thoracic surgery department for scheduled operation .
although his symptom was relieved , post - treatment chest ct still revealed a multi - cystic lesion in the lateral side of right lung showing plump vascular supply through intercostal arteries or pulmonary arteries ( fig .
it showed no segmental or lobar distribution . under the clinical impression of congenital cystic adenomatoid malformation ( ccam ) ,
cut section of the specimen revealed a multi - lobulated cystic lesion filled with blood , measuring 7 cm in extent ( fig .
microscopic examination revealed that the cystic lining consisted of dilated thick vascular structure ( fig .
the final pathologic diagnosis was given as fistulous arteriovenous malformation / hemangioma ( avmh ) .
pavf is described as abnormally dilated vessels that provide a right - to - left shunt between pulmonary artery and pulmonary vein and is divided into simple and complex type .
the literature review showed that abnormal communications between pulmonary arteries and veins have been given various names including pavf , arteriovenous aneurysm , and arteriovenous hemangioma [ 1 - 3 ] .
while pavfs have been often described as pulmonary arteriovenous malformation in several reports [ 1 - 5 ] , we suggest that pulmonary avmh should be used preferably to describe tumorous hemangioma lesion and pavf should be used preferably to describe abnormal vascular communication .
pavfs are divided into simple and complex type , and the former is more common .
simple pavfs are those of a well - defined peripheral nodule and may be rounded or multi - lobulated .
histologically , simple type presents as a single aneurysmal sac and contains a single segmental artery feeding the malformation .
complex pavfs involve multiple abnormal vessels and consist of one or more lobulated venous sacs of variable size supplied by more than one feeding artery , often arising from adjacent segmental pulmonary artery branches .
two patients ( cases 1 and 2 ) presented with solitary aneurysmal vascular lesion , which corresponded to simple pavf .
these incidental lesions did not cause any clinical symptom and surgical removal was successfully performed .
on the other hand , case 3 presented with diffuse vascular lesion causing arteriovenous shunt and was consistent with the diagnosis of complex pavf .
lastly , case 4 showed a localized multi - lobular vascular lesion grossly mimicking pulmonary sequestration or ccam .
the histology of case 4 was unusual and also different from cases 1 , 2 , and 3 in that it had no definite aneurysmal sac or shunt formation . while avmh is an acquired tumor - like condition characterized by complex thick - walled vessels
, it was not certain whether case 4 was a tumorous condition of avmh or not .
however , we concluded that the terminology of avmh would represent the histologic characteristics of case 4 the best in that there was definite localized overgrowth of thick vessels .
although it did not cause serious hemodynamic or pulmonary symptoms , his episodes of pneumonia may probably be related to this lesion .
while most pavf patients are known to have hht , patients in our series did not .
pavfs are not easily diagnosed routinely , due to its rarity and its unspecific findings on routine examinations .
ct is generally considered the reference standard investigation for diagnosing pavfs . in terms of treatment ,
the four rare cases of surgically resected pavfs described herein show various spectrums of clinical and histologic features .
they can present as either localized or diffuse , and they can involve either thin or thick blood vessels .
 pulmonary arteriovenous fistula ( pavf ) is abnormally dilated vessels that provide a right - to - left shunt between pulmonary artery and pulmonary vein and is clinically divided into simple and complex type . here 
 , we report four cases of surgically resected sporadic pavfs presenting various clinical and histologic spectrums . cases 1 ( a 57-old - female ) and 2 ( a 54-old - female ) presented as incidentally identified single aneurysmal fistulas and the lesions were surgically removed without complication . on the other hand , case 3 ( an 11-old - male ) showed diffuse dilated vascular sacs involving both lungs and caused severe hemodynamic and pulmonary dysfunction . 
 embolization and surgical resection of the main lesion failed to relieve the symptoms . 
 case 4 ( a 36-old - male ) had a localized multiloculated cyst clinically mimicking congenital cystic adenomatoid malformation . 
 microscopically , the lesion consisted of dilated thick vessels , consistent with the diagnosis of fistulous arteriovenous malformation / hemangioma . 
CASE REPORTS
Case 1
Case 2
Case 3
Case 4
DISCUSSION