PB0970 - Klippel-Trenaunay Syndrome: a rare disorder with complex hemostatic and thrombotic challenges

Background: Klippel-Trenaunay Syndrome (KTS) is a rare, genetic vascular proliferative disorder that manifests with arteriovenous malformations (AVM), chronic thrombocytopenia, thrombophilia, portal vein thrombosis and limb asymmetry. The estimated incidence is between 2 and 5 per 100,000 and often presents in infancy with limb asymmetry and progresses throughout life. Its pathogenesis has been linked to somatic mutations in PIK3 leading to dysregulation in the mTORC2 pathway. It is grouped with other overgrowth syndromes and collectively termed PIK3CA-related overgrowth spectrum (PROS) but awareness is limited due to the rarity of the syndrome.

Aims: Here we present the case of a 17-year-old female with KTS, splenomegaly and portal vein thrombosis who presented for evaluation of esophageal varices bleeding. Initial blood counts showed leukocytes 4.3 K/uL, hemoglobin 8.1 g/dL, platelet 45 K/uL and she received a massive transfusion protocol for active hematemesis. In regards to her portal vein thrombosis, she had been diagnosed one year prior and was not anticoagulated. Endoscopy revealed esophageal and gastric varices with stigmata of recent bleeding.

Methods: She underwent open splenectomy and splenorenal shunt with side-to-side anastomosis. Surveillance CT imaging revealed patent splenorenal shunt and decreasing SMV thrombosis and decreasing gastric and esophageal varices.

Results: Laboratory studies showed resolution of thrombocytopenia and progression to thrombocytosis.

Conclusion(s): This case highlights a rare vascular disorder with hematologic complications including thrombocytopenia, AVMs and thrombosis. Patients with KTS often have both hemostatic and thrombotic complications, even independent of liver disease, due to thrombocytopenia and vascular malformations. The syndrome is often diagnosed with clinical history and imaging studies. The management is largely supportive, though low-dose aspirin therapy appears to be beneficial in patients with AVMs. Therapies targeting mTOR and PIK3, sirolimus and alpelisib, are treatment options for patients with symptomatic KTS or for those with functional impairment.