A case report of membranous occlusion of the subclavian vein: a rare cause of McCleery syndrome.

Patients presenting with periodic swelling of the upper extremity without thrombosis are diagnosed with McCleery syndrome. There have been sporadic cases reported over the past decades. Due to the rarity of this disease, no standard consensus on diagnosis and treatment of McCleery syndrome was established. Subclavius tendon and anterior scalene muscle compression were proposed as the primary cause of McCleery syndrome. Partial resecting muscle, tendon or ligament was recommended as therapies. We report one rare case of membranous occlusion of the subclavian vein (SCV) that leads to periodic swelling of upper extremity and diagnosis of McCleery syndrome was made. This 21-year-old man complained of swelling and pain in the right upper extremity after strenuous exercise lasting for 3 months. Physical examination, spinal X-ray and magnetic resonance imaging showed no signs related to classic venous thoracic outlet syndrome (VTOS). Duplex ultrasonography demonstrated membranous occlusion without thrombosis at the proximal end of the right SCV. The lesion was confirmed by venography. Treated by balloon dilation alone, the patient recovered uneventfully during 18 months of follow-up. Repeated duplex ultrasonography revealed patency of the SCV. To our best knowledge, our case provides the first reported membranous occlusion of the SCV. Excluding the presence of thrombosis in SCV, he was diagnosed with McCleery syndrome and was cured by balloon dilation alone. We can learn from this rare case that membranous occlusion of veins can be a rare cause of McCleery syndrome and is worthy of careful consideration and differentiation of VOTS.