A 16-year-old girl presented with painful right-leg varicosities. She was actively involved in several sports, and noticed increasingly painful varicosities in her posterior-lateral thigh and extending distally down to her foot. Shortly after her birth purple-red superficial discoloration along her right leg extending up to her flank that abruptly terminated prior to crossing midline was identified. Several right limb-shortening procedures were required. Initial management included gradient compression hose with improvement in her pain. She presented several years later with worsening symptoms and underwent resection of her symptomatic vein clusters followed by targeted sclerotherapy several months postoperatively. Figure 41-1 illustrates a typical case of Klippel-Trenaunay syndrome (KTS). While generally benign, KTS can have unusual presentations that benefit from surgery, sclerotherapy, and/or thermal ablation treatment.

• 
  

  Rare condition, sporadic in nature, no clear genetic inheritance pattern, but may have multifactorial inheritance pattern

  
  
• 
  

  Occurs in all ethnic groups equally¹

  
  
• 
  

  Affects males and females equally

  
  
• 
  

  Lack of large studies, but incidence postulated at 1 in 100,000 live births²

  
  
• 
  

  Most commonly diagnosed in childhood

• 
  

  Unclear and controversial etiology. Competing theories include the partial persistence of an embryologic vascular system, mesodermal developmental abnormalities, and venous hypertension as a result of vascular agenesis, atresia, or hypoplasia possibly related to compression of the deep venous system by abnormal muscles or fibrovascular cords.^{3,4, and 5}

  
  
• 
  

  May be associated with increased maternal age, increased paternal age, and increased number of pregnancies. Vascular malformations are found at increased rates in family members of patients with KTS.²

• 
  

  Classic triad described by Klippel and Trenaunay in 1900 consists of capillary malformations, varicose veins or venous malformations, and osseomuscular limb hypertrophy.

  
  
• 
  

  Cutaneous appearance of capillary malformations (previously referred to as a port-wine stain) that are usually present at or soon after birth.

  
  
• 
  

  Limb hypertrophy involves both bone and soft tissue, and in rare circumstances involves a truncal location.⁶ Although it may be evident early, limb hypertrophy is often recognized after the affected individual begins walking.

  
  
• 
  

  Lymphatic abnormalities can often be present and range from hypoplasia to aplasia. Lymphedema can exacerbate limb hypertrophy and venous congestion.

  
  
• 
  

  A related syndrome, Parkes-Weber syndrome (PWS), is often confused with KTS, and is characterized by the presence of arteriovenous fistulae or arteriovenous malformations in addition to the constellation of clinical findings classically described with KTS.

  
  
• 
  

  Diagnosis is made clinically, with the presence of at least two of the three main features.