a 59-year - old man presented with a swelling of the left lower extremity that had begun two months earlier . for further evaluation , we performed computed tomography ( ct ) venography and pelvic magnetic resonance imaging ( mri ) . the ct venography axial images showed a 2.3 cm cystic mass compressing the left common femoral vein ( fig . the mri images showed a cystic mass compressing the left common femoral vein as well ( fig . we suspected adventitial cystic disease ( acd ) of the common femoral vein , and the patient underwent an operation . under general anesthesia in a supine position , the femoral artery and vein were dissected for about 5 cm with a longitudinal incision on the left inguinal area . surgical exploration showed an approximately 2.0 cm sized cystic mass that originated from the adventitia of the common femoral artery and was compressing the common femoral vein . the cyst that had adhered to the femoral artery was removed first , and the part of the wall that was attached to the cyst in the femoral artery was partially resected . angioplasty was performed to repair the femoral artery whose wall was partially resected . because the patient had had a partial circulation problem in the vein before the surgery and thus venous obstruction was possible , a polytetrafluoroethylene ( ptfe ) patch was used for angioplasty instead of using an autologous vein graft . a cystic mass excision with ptfe roofing angioplasty microscopically , the presence of a mucinous cyst and vessel wall degeneration confirmed cystic adventitial disease of the common femoral artery ( fig . acd is an unusual cystic tumor of the blood vessels characterized by the accumulation of a mucinous substance in the adventitia . acd is an uncommon disease that was first described in 1947 by atkins and key . acd accounts for only 0.1% of cases of vascular disease , and among them , 85% of all cases of acd occur in the popliteal arteries , while fewer cases appear in the femoral arteries . the first case of common femoral artery acd was reported by jaquet and meyer - burgdorff   in 1960 . it was reported that the prevalence is 5 times higher in males than in females . the age of occurrence ranges from 11 to 72 years , and the average age is 42 . four theories have been proposed about the nature of acd : 1 ) the theory that it is a systemic disorder of the connective tissue ; 2 ) the theory that it is a chronic degenerative change due to repetitive trauma ; 3 ) the developmental theory , which maintains that a joint - related ganglion - like structure is incorporated into the vessels during embryologic development ; and 4 ) the ganglion theory that arterial adventitial cysts originate from joint capsular synovial structures . thus continuous trauma from using fishing tools in contact with the thighs was suspected to have contributed to the lesion . on the other hand , considering that the lesion occurred unilaterally and did not appear on the opposite thigh , repetitive trauma is not an obvious explanation for the lesion . the symptoms of acd can include unilateral claudication of the lower extremity , and in rare cases it shows ischemic neuropathy such as paresthesia , pain , and rhigosis . other possible symptoms include arterial obstruction that results in the pulse in the femoral , the popliteal , and the dorsal pedis arteries being weak or not palpable . however , the main symptom in our case was the uncommon occurrence of swelling that appeared due to the venous obstruction . in addition , the pulse of the blood vessels of the lower extremities was fully palpable . recently , it has been accepted that angiography using 3-dimensional ct alone is now considered sufficient for diagnosis . ct angiography is considered to be an important test because it not only determines the site and extent of stenosis but is also useful in evaluating the entire circulation system . aspiration of the cyst under ct or ultrasonography is a minimally invasive method , but it is difficult to perform and the cyst has a high recurrence rate . this method also has a higher recurrence rate than complete resection involving the vessel with artificial material interposition . interposition provides better long - term patency than the other methods . in this case , in the pre - surgical assessment the lesion was misdiagnosed as originating from the femoral vein instead of from the femoral artery . in addition , recurrence will be minimized by our having performed the arterial repair and interposition as well as the cystic mass excision . thus we report here a case of acd , a rare disease , with unusual symptoms , that was successfully treated with surgery .
arterial adventitial cystic disease is an uncommon type of non - atherosclerotic peripheral vessel disease . 
 most cases of arterial adventitial cystic disease occur in the popliteal arteries ; however , fewer cases have been reported in the femoral arteries . 
 a 59-year - old male patient visited the hospital with a complaint of a swelling on the lower extremity that had begun two months earlier . suspecting deep vein thrombosis based on a physical examination and ultrasonography from another hospital , tests were performed . magnetic resonance imaging ( mri ) 
 was performed for exact diagnosis because venous adventitial cystic disease was suspected by computed tomography venography . 
 the mri indicated venous adventitial cystic disease as well . 
 thus , a cystic mass excision was performed . in the end , a cystic mass compressing the common femoral vein that originated from the common femoral artery was diagnosed based on the macroscopic findings . 
 this case is reported because blood circulation in the vein was impeded due to arterial adventitial cystic disease , and the symptoms improved after the cystic mass excision and polytetrafluoroethylene roofing angioplasty .