A 53-year-old man was admitted to our hospital with the complaint of neck pain and dyspnea. His blood examination revealed increased C-reactive protein and amylase levels. Enhanced computed tomography (CT) images demonstrated a retropharyngeal and a mediastinal low-density area extending to the portal area. He was diagnosed with pancreatic pseudocyst from the abdominal cavity to the cervical region accompanied by spontaneous rupture into the portal vein. Endoscopic ultrasound-guided cyst drainage (EUS-CD) of the most inferior cavity around the superior mesenteric artery was performed through the gastric wall. No adverse events were recorded during the procedure, and a near-complete resolution of his symptoms and the pseudocyst was achieved.