Microcystic lymphatic malformation of the small intestine presenting as acute abdominal pain in a 5-year-old boy: a case report and review of the literature.

BACKGROUND: Lymphatic malformations are rare benign congenital anomalies of the lymphatic system, most commonly affecting the head and neck. Gastrointestinal involvement is uncommon, and lymphatic malformations of the small intestine are particularly rare. Microcystic lymphatic malformations infiltrating the bowel wall may present with nonspecific clinical and radiological features, making preoperative diagnosis challenging. Reporting such cases is important to raise awareness of this rare entity as a potential cause of acute abdominal pain in children.

CASE PRESENTATION: A 5-year-old Vietnamese boy presented with acute onset abdominal pain, vomiting, and fever of 1-day duration. Physical examination revealed mild lower abdominal tenderness without a palpable mass. Abdominal ultrasonography demonstrated a mixed echogenic cystic lesion, while contrast-enhanced computed tomography revealed a segment of small intestine with irregular wall thickening, scattered calcifications, and tortuous intramural vessels. Differential diagnoses included vascular malformation, inflammatory bowel disease, and intestinal infection. Due to the acute presentation and inconclusive imaging findings, exploratory laparotomy was performed. Intraoperatively, a markedly thickened and hypervascularized segment of small bowel with dark purple discoloration was identified and resected, followed by primary end-to-end anastomosis. Histopathological examination revealed numerous small lymphatic channels infiltrating all layers of the intestinal wall with focal intralesional hemorrhage, confirming the diagnosis of microcystic lymphatic malformation. The postoperative course was uneventful, and the patient recovered well without complications.

CONCLUSIONS: Microcystic lymphatic malformation of the small intestine is a rare but important differential diagnosis in children presenting with acute abdominal pain and localized bowel wall thickening. Because clinical and imaging findings are often nonspecific, definitive diagnosis usually relies on histopathological examination. Complete surgical excision provides both diagnostic confirmation and curative treatment, with excellent short-term outcomes.