Longitudinal Ultrasonographic Appearance of an Atypical Tendinous Variant of Popliteal Artery Entrapment Syndrome in an Adolescent

A 15-year-old boy presented with left fifth-toe ulceration, claudication, and rest pain. Computed tomography angiography demonstrated proximal-to-mid popliteal artery occlusion. Duplex ultrasonography revealed thrombotic occlusion and a slender tendon crossing the artery, which appeared more conspicuous longitudinally than transversely. Magnetic resonance imaging showed apparent continuity with the main tendon of the medial head of the gastrocnemius, supporting an atypical variant of popliteal artery entrapment syndrome. Surgery was declined. At 3 months, the ulcer had healed, and symptoms improved during medical therapy, although perfusion indices remained abnormal. Longitudinal ultrasonography may facilitate delineation of slender compressive tendons.