The Role of Endoscopic Ultrasonography in the Diagnosis of Retroperitoneal Lymphatic Malformations.

Lymphatic malformation (LM), formerly known as lymphatic cyst, is an extremely rare condition with no specific symptoms, often incidentally detected during examinations for other diseases and confirmed by postoperative pathology. Endoscopic ultrasound (EUS), a non-invasive tool, plays a critical role in diagnosing LM and reducing unnecessary surgeries. We report the case of a young male with 4-day upper abdominal pain was admitted. Imaging (chest CT, enhanced upper abdominal CT, MRI+MRCP) revealed a cystic lesion in the pancreatic head connected to a tubular structure. EUS further showed the lesion was linked to an enlarged lymph node, leading to a diagnosis of retroperitoneal LM, later confirmed by pathology. EUS facilitates early diagnosis by visualizing ductal continuity, avoiding unnecessary interventions like biopsy or surgery.