<prompt> A patient presented with local gigantism of the leg and increased pulsations of the lower limb veins. Most probable diagnosis is :TumorAV fistulaVaricose veinsIncompetence of the saphenofemoral junction  <response>: The patient is having congenital AV fistula which has caused overgrowth of the leg.Arteriovenous fistula AVF AVF may be congenital or acquired by the trauma of a penetrating wound, or surgically created for renal dialysisStructural effect on veins Veins are arterialised, they become dilated tortuous and thick walled.Physiological effects of fistula -Increased pulse pressure Increased systolic decreased diastolicEnhanced venous return result in Increased HR and Increased CO.Left ventricular enlargement and later cardiac failure may occurA congenital fistula in the young may cause overgrowth of limb.In the leg, indolent ulcers may result from relative ischemia below the short circuit.Clinical signsA pulsatile swellingA thrill on palpationContinuous bruit on auscultationNicoladonis sign or Branham sign Pressure on the artery proximal to fistula causes the swelling to diminish in size, a thrill or bruit to cease, the pulse rate to fall and the pulse pressure return to normal. 