回顾性分析1例5岁7月龄原发性小肠淋巴管扩张症(PIL)患儿的临床表现、实验室指标、内镜病理及淋巴核素显像特征，并随访治疗归转。患儿以腹泻、腹胀、手足搐搦起病。实验室检查示重度低白蛋白血症（16.4 g·L^-1）、低IgG（2.32 g·L^-1）、淋巴细胞减少（0.82×10⁹/L）及低钙低镁血症，影像学检查提示多浆膜腔积液，胃肠镜检查见十二指肠及回肠末端黏膜弥漫性白色雪花样物质，病理示淋巴管扩张伴炎细胞浸润。特征性发现⁹⁹Tc^m-DX淋巴核素显像提示左静脉角持续显影，提示胸导管出口梗阻。经低脂高蛋白、高MCT饮食联合白蛋白输注等治疗，7天后白蛋白升至26.8 g·L^-1，症状显著缓解。儿童原发性小肠淋巴管扩张症的主要临床表现为腹泻、腹胀、水肿、低蛋白血症、电解质紊乱；淋巴核素显像明确了胸导管梗阻这一关键病理机制，为该病的病因诊断提供了可靠的影像学依据。

A retrospective analysis of the clinical manifestations, laboratory indicators, endoscopic pathology, and lymphoscintigraphy characteristics of a 5-year-7-month-old child with Primary Intestinal Lymphangiectasia (PIL) was conducted, along with a follow-up of treatment outcomes. The child presented with symptoms of diarrhea, abdominal bloating, and tetany in hands and feet. Laboratory tests revealed severe hypoalbuminemia (16.4 g·L^-1), low IgG (2.32 g·L^-1), lymphocytopenia (0.82×10⁹/L), and hypocalcemia with hypomagnesemia. Imaging studies indicated multiple serous effusions, and gastrointestinal endoscopy showed diffuse white, snowflake-like substances on the mucosa of the duodenum and terminal ileum. Pathology demonstrated lymphatic dilation with inflammatory cell infiltration. Characteristic findings from ⁹⁹Tc^m-DX lymphoscintigraphy indicated persistent imaging of the left venous angle, suggesting obstruction at the thoracic duct outlet. Treatment with a low-fat, high-protein, high-medium-chain triglyceride (MCT) diet combined with albumin infusion led to a significant increase in albumin levels to 26.8 g·L^-1 after 7 days, with a marked alleviation of symptoms. The main clinical manifestations of primary intestinal lymphangiectasia in children include diarrhea, abdominal bloating, edema, hypoproteinemia, and electrolyte disturbances. Lymphoscintigraphy confirmed the key pathological mechanism of thoracic duct obstruction, providing a reliable imaging basis for the etiological diagnosis of the disease.