Presentation
History of sudden onset right arm pain five days ago during playing gym. No history of direct trauma or abnormal skin discoloration, clinical examination showed mild tender small oval shaped firm mass moves freely from side to side but has a limited movement from up to down.
Patient Data
Lobulated mass with different signal intensities and internal partial septations is seen rising from the basilic vein posteromedially to the brachial artery.
On FSE FS sequence, it is clear that the lesion has no relation to the adjacent artery and nerve.
Coronal STIR: This sequence shows the orientation of the aneurysm to the basilic vein and the nearby brachial artery.
After IV contrast injection, the aneurysm could not attain MRI signal intensity similar to basilic vein suggesting presence of thrombosis inside the aneurysm. Note there is dilatation in the basilic vein proximal to the aneurysm. If this mass originated from structures outside the basilic vein, dilatation should be distal not proximal to the mass.
Different MRI protocols explaining why this mass is a basilic thrombosed saccular aneurysm and not arising from the nearby brachial artery and ulnar nerve.
On color Doppler and pulsed wave Doppler, the basilic vein aneurysm appears hypoechoic with partial venous blood flow inside suggesting thrombosis.
Case Discussion
Differential diagnosis would be angiosarcoma of basilic vein. See this case for comparison (Bilateral and asynchronous angiosarcoma - basilic vein).