Chapter 17

### PATIENT STORY

A 32-year-old man presents with right lower extremity edema, pain, lipodermatosclerosis, and history of recurrent right ankle ulcers. Physical examination demonstrates port-wine stains overlying his right upper and lower extremity, as well as the right hemithorax and abdomen (Figure 17-1). He states that these lesions have been present since birth. A clear asymmetry of his lower extremity is also noted with the right leg being larger than the left. Some soft tissue masses are also present, mainly in his lower extremity with an overlying cutaneous bluish discoloration. A duplex ultrasound documents a heterogeneous network of hypoechoic vessels with monophasic flow patterns and an incompetent great saphenous vein that is feeding many of the dilated venous structures. The deep venous system is normal and intact.

###### FIGURE 17-1

Magnetic resonance imaging (MRI) is the imaging modality of choice. The vascular malformation appears as a hyperintense lesion in spin-echo sequences. MRI is also essential in identifying the relationship of the malformation with the normal vasculature.

T2-weighted hyperintense magnetic resonance imaging or magnetic resonance angiography (MRI or MRA) demonstrates low-flow lesions mostly in his upper and right lower extremities (Figure 17-1) with osteomuscular hypertrophy of the right leg. The iliac veins and inferior vena cava are normal and patent.

A diagnosis of the unique vascular malformation, Klippel-Trenaunay syndrome (KTS), is made. The treatment plan is to eliminate the great saphenous vein using thermal ablation, and to treat the remainder of the venous malformations with ultrasound-guided foam sclerotherapy in multiple sessions.

### INTRODUCTION

Congenital vascular anomalies are a unique group of vascular disorders whose treatment remains a significant challenge. The groundbreaking work of Mulliken and Glowacky in characterizing vascular anomalies provides the definition of vascular malformations as "diffuse or localized embryologically developed errors of vascular morphogenesis leading to true structural anomalies."1 It is critical to understand that with this classification and definition, hemangiomas are considered vascular tumors, as they exhibit a different clinical appearance and biologic behavior. For this reason, vascular malformations and hemangiomas will be discussed separately here.

### HEMANGIOMAS

Hemangiomas are the most common pediatric vascular tumor, and as such represent a proliferative disorder in contrast to vascular malformations, which are nonproliferative.

#### Epidemiology

They are congenital and occur in 7% to 10% of children, and 30% are evident at birth, while the remainder appears within the first 4 weeks of life. The female:male ratio is typically 5:1.2

#### Etiology and Pathophysiology

The etiology is unknown. Recently, overexpression of the notch signaling pathway has been associated with the progression of hemangioma stem cells into hemangioma endothelial cells. Abnormal vascular endothelial growth factor (VEGF) production has also been observed.2 Increased estrogen levels ...

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