Lymphatic Malformation: A Rare Cause of Pediatric Abdominal Pain

Congenital lymphatic malformations, also known as lymphangiomas, are benign vascular proliferations of fluid-filled channels or spaces that are thought to arise from failure of the lymphatic system to properly connect to the venous system during embryologic development.

The lymphatic system of the body is derived from the lymphatic endothelial cells on the dorsolateral side of the anterior cardinal veins during the 6th embryonic week.¹ Between the 12^th and 14^th weeks of gestation, lymph sacs anastomose with each other to form a lymphatic plexus, which expand and remodel into a highly branched network of capillaries, lymphatic vessels, and ducts.¹ When these sacs fail to communicate with the rest of the lymphatic system during development, the lymphatic vessels dilate and form masses as lymph accumulates.

Lymphatic malformations are typically present at birth and grow bigger with the child. This usually leads to a diagnosis in children by 5 years old, and some case series have observed a slight predominance in male children.^2-4 The malformations usually arise from the neck and axillary regions. Abdominal lymphatic malformations are rare and comprise less than 5% of all lymphatic malformations.⁵ Within the abdominal cavity, these malformations can arise from solid organs (pancreas, liver, spleen), mesentery, retroperitoneum cavity, or gastrointestinal tract. Isolated occurrence in the small intestine mesentery is rare, accounting for less than 1% of all lymphangiomas.⁵ Grossly, lymphatic malformations appear as cystic lesions with a thin-walled and smooth external surface.^3,4 The fluid in the cysts may be serous, hemorrhagic, or chylous. 

Mesenteric cystic lymphangiomas are the most common type of abdominal malformations. Complications of mesenteric lymphatic malformations occur as they increase in size and include volvulus, gastrointestinal obstruction, and bowel hemorrhage.⁵ Gastrointestinal tract lymphatic malformations are intramural lesions that are frequently detected incidentally on imaging or during endoscopy in adult patients.⁶ Hepatic lymphatic malformations are uncommon and may be seen in isolation in older children or as a part of other systemic lymphatic malformations in early childhood. Splenic lymphatic malformations are usually subcapsular and not in intraparenchymal locations. They appear as multiple focal lesions on computed tomography (CT) and may closely resemble pseudocysts, abscesses, or neoplastic lesions. Renal lymphatic malformations are rare and usually present as focal cystic lesions on imaging.⁷ Pancreatic lymphatic malformations can be located within the pancreatic parenchyma or directly attached to the pancreas by a pedicle. They may mimic pseudocysts or neuroendocrine neoplasms in children. Retroperitoneal lymphatic malformations are extremely rare and usually present in adolescents and adults.⁷

The clinical presentation varies depending on the location and size of the malformation. Most malformations are painless masses and may be incidentally found on imaging obtained to evaluate other complaints. However, the most common presentation is abdominal pain with possible palpable abdominal mass that may be tender or nontender causing a partial small bowel obstruction.^4,5,8 Symptoms suggestive of an acute abdomen including abdominal pain, abdominal distension, emesis, constipation, ascites, palpable mass, or fever.^8,9 In a case series of 21 children, the mean time between initial presentation of symptoms and diagnosis was 27 days and 10 patients presented with acute symptoms.⁴ Retroperitoneal lymphatic malformations may cause ureteric obstruction and hematuria.⁷

Imaging results can suggest a diagnosis of lymphatic malformation and aid in accurate surgical planning. Lymphatic malformations appear as solid multilocular masses and often contain multiple anechoic cystic spaces on ultrasonography. Lymphangiomas may contain echogenic debris or homogeneous fluid, and ultrasonography can help differentiate lymphangiomas from simple mesenteric cysts.^10,11 On CT, multilocular lymphangiomas are septated and the fluid is usually homogenous with low attenuation values. Intravenous contrast enhances the walls and septa of the malformation.^4,10 Negative attenuation values may indicate presence of chylous fluid. Other uncommon findings on CT include hemorrhage or calcifications. Magnetic resonance imaging reveals fluid that is hypointense on T1-weighted images and hyperintense on T2-weighted images. Heterogeneous signal intensity can suggest chylous or hemorrhagic fluid.

The diagnosis is confirmed after surgical excision and histopathological evaluation. Complete surgical intervention for removal should be emergently performed if there is severe abdominal distension, volvulus, or peritonitis caused by torsion or rupture.¹² A complete resection rate of 82% has been reported in children and rarely requires partial bowel resection.⁷ Elective surgery is acceptable if a child’s abdominal pain cannot be managed with conservative therapy.¹²Percutaneous image-guided intralesional sclerotherapy has been shown to be effective as primary intervention in children with intra-abdominal lymphatic malformations.¹³ However, it is limited to few pediatric institutions at this time, and further studies are required to evaluate for complete resolution and recurrence rates. Recurrence after resection is unlikely in children within two years and usually does not require repeat exploration.

Although lymphatic malformations are rare and usually do not manifest as acute abdomen, they should always be considered in the differential diagnosis in a previously healthy child who presents with abdominal pain and palpable mass.

References:

1. Som PM, Francois M. The current concepts of the embryology of the lymphatic system. Neurographics. 2017;7(2):129-150. doi:10.3174/ng.2170198
2. Kim S, Kim H, Lee C, et al. Clinical features of mesenteric lymphatic malformation in children. Journal of Pediatric Surgery. 2015;51(4):582-587. doi:10.1016/j.jpedsurg.2015.11.021
3. Suthiwartnarueput W, Kiatipunsodsai S, Kwankua A, et al. Lymphangioma of the small bowel mesentery: a case report and review of the literature. World Journal of Gastroenterology. 2012;18(43):6328-6332. doi:10.3748/wjg.v18.i43.6328
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8. Weeda VB, Booij KAC, Aronson DC. Mesenteric cystic lymphangioma: a congenital and an acquired anomaly? Two cases and a review of the literature. Journal of Pediatric Surgery. 2008;43(6):1206-1208. doi:10.1016/j.jpedsurg.2008.01.075
9. Kumar B, Bhatnagar A, Upadhyaya VD, et al. Small lymphangioma presenting as an acute abdomen with relevant review of literature. Journal of Clinical and Diagnostic Research. 2017;11(6):PD01-PD02. doi:10.7860/JCDR/2017/22703.9962
10. Levy AD, Cantisani V, Miettinen M. Abdominal lymphangiomas: imaging features with pathologic correlation. American Journal of Roentgenology. 2004;182(6):1485-1491. doi:10.2214/ajr.182.6.1821485
11. Konen O, Rathaus V, Dlugy E, et al. Childhood abdominal cystic lymphangioma. Pediatric Radiology. 2002;32(2):88-94. doi:10.1007/s00247-001-0612-4
12. Muramori K, Zaizen Y, Noguchi S. Abdominal lymphangioma in children: report of three cases. Surgery Today. 2009;39(5):414-417. doi:10.1007/s00595-008-3854-z
13. Chaudry G, Burrows PE, Padua HM, et al. Sclerotherapy of abdominal lymphatic malformations with doxycycline. Journal of Vascular and Interventional Radiology. 2011:22(10):1431-1435. doi:10.1016/j.jvir.2011.06.021