Klippel–Trénaunay syndrome (KTS) is a rare congenital capillary–lymphatic–venous condition characterized by the following clinical triad: capillary malformations (port-wine stains), congenital venous or veno-lymphatic malformations, and bone and/or soft-tissue hypertrophy. A phenotypic diagnosis of KTS requires the presence of only two of these three cardinal features [1]. The radiographic appearance of soft tissue, bone, and vessels can be assessed using plain films, sonograms, or CT and MRI [4].
The capillary malformation in KTS is usually red to purple in color, which is often described as a port-wine malformation. The venous or veno-lymphatic malformation is extensive and does not involve high-flow arteriovenous malformation (AVM). Liguori [2] et al. reported that 70% of KTS patients have a “vein of Servelle,” also known as a lateral marginal vein, extending from the foot or ankle to the infra-inguinal region.Both malformations typical of KTS were present in our case, who had red spots as well as the lateral marginal vein in the left lower extremity.
In genetic studies, both KTS and Parkes Weber syndrome (PWS) are associated with the PI3K/AKT/mTOR signaling pathway [1]. The two syndromes have many features in common, such as cutaneous port-wine stains, asymmetrically enlarged limbs, and vascular malformations, which can lead to misdiagnosis. The critical clinical difference between these two disorders is the type of vascular malformation. PWS is associated with high-flow AVMs whereas KTS is associated with low-flow (venous and/or lymphatic) malformations [1]. Images of the present case revealed venous malformation but not AVM, further confirming the diagnosis of KTS.
Hemangioma is the most common benign primary tumor of the spleen. Kocaman et al. [5] reported that splenic hemangiomatosis may occur in KTS patients, and is often asymptomatic. However, in the present case, the profound tumor was located in the mesenteric region rather than the spleen. Further, the tumor was initially detected in prenatal screening and was suspected to be lymphangiohemangioma. This early manifestation of capillary–lymphatic–venous abnormality may be another key to diagnosing KTS.
In 1900, the French physicians Klippel and Trénaunay classified KTS into four levels of severity [3]. The four levels are as follows: class I, venous/phlebectasicdysplasias; class II, arterial dysplasias; class III, arterial and associated venous dysplasias; and class IV, mixed angiodysplasias. Because we observed no arterial involvement in the present case, KTS was categorized as class I (venous/phlebectasicdysplasias).
According to Sikakulya et al. [6], KTS can be associated with several complications, such as deep venous thrombosis, bleeding, pulmonary embolism, stasis dermatitis, cellulitis, and limb enlargement. Although no definitive treatment for KTS has been approved, an early approach consisting of multidisciplinary management should be considered. Macrocystic lymphatic malformations can be treated with coil embolization or sclerotherapy, while microcystic malformation might be treated only with oral sirolimus or doxycycline [1, 2]. In addition, laser therapy is used to reduce the port-wine stains. All these management approaches are primarily symptomatic treatment and prevent further complications [7]. Prognosis depends on the severity of the malformations and associated anomalies.
In conclusion, we report a case of KTS (class I) in a newborn with a profound abdominal lymphangiohemangioma. She presented with the classical KTS features of capillary and venous malformations, which allowed her condition to be distinguished from PWS. Early distinction between KTS and PWS was possible based on the identification of significant hemodynamic arteriovenous fistulas, which is essential for further treatment and prognosis prediction. Additionally, she presented with a unique abdominal lymphangiohemangioma in prenatal MRI, which served as an important clue for early diagnosis of KTS. The prognosis of KTS is variable and needs to be treated with multidisciplinary management.