A 35-year-old Caucasian man with a pulsating painful flank mass was referred for further evaluation and treatment. The mass had been present for over 15 years and had enlarged over the past year along the right lower back and flank in an area underlying a birth mark (Figure 42-1). Examination confirmed a 15-cm tender mass with overlying erythematous skin changes. A thrill was palpable over the mass, and a continuous bruit was present on auscultation.

The lesion was confirmed to be a localized arteriovenous malformation (AVM) with minimal involvement of the surrounding tissues, as demonstrated on abdominal computed tomography (CT) scanning with angiography including three-dimensional (3D) reconstruction (Figure 42-2).

Conventional angiography (Figure 42-3) confirmed the presence of an extensive AVM lesion with multiple feeding arteries. The massively dilated venous outflow due to the fistulous lesion producing a hemodynamically advanced condition.

Direct puncture, transvenous embolization utilizing 0.035 Bentsen wires was performed preoperatively for subsequent open resection of the lesion to reduce intraoperative bleeding. Complete excision of the lesion filled with the coils was performed safely (Figure 42-4), leaving a minor residual lesion that was treated with conventional sclerotherapy (Figure 42-5). Follow-up CT angiography and 3D reconstruction demonstrated an excellent result (Figure 42-6).

Congenital Vascular Malformation (Arteriovenous Malformation Subtype)

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  Congenital vascular malformations (CVMs) are inborn vascular defects that present at birth and may become clinically evident later in life.

  
  
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  The AVM is the least common CVM, representing 10% to 15% of all clinically significant CVMs.

  
  
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  The majority of CVMs (85%-90%) are either a venous malformation (VM)¹ or a lymphatic malformation (LM).²

Hemangioma

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  The neonatal or infantile hemangioma is not a vascular malformation but a vascular tumor.

  
  
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  Hemangioma is a vascular tumor that originates from endothelial cells and is present in the early neonatal period.

  
  
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  Hemangiomas occur in approximately 1% to 2% and 10% of white infants at birth and at age 1 year, respectively.

  
  
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  Hemangiomas occur most commonly in white infants, with an incidence rate 10 to 12 times that of black and Asian infants.

  
  
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  Females are affected more often than males by a ratio of 3:1.

Congenital Vascular Malformation (Arteriovenous Malformation Subtype)

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  CVMs are inborn vascular defects that present at birth and continue to grow at a rate proportional to the growth rate of the body.

  
  
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  The AVM is a congenital anomaly of the vascular system where the anatomic defect produces shunting of arterial blood into the venous system.

  
  
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  The vast majority of the AVMs exist alone as independent lesions, but occasionally occur with other CVM lesions.

  
  
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  AVM itself is further subgrouped into two different types, based on the embryological stage where developmental arrest has occurred: extratruncular and truncular lesions.³

The AVM type most often associated with unpredictable biological behavior is the extratruncular lesion that has unique, pathologic, embryological characteristics. Its proliferative potential is derived from the mesenchymal cells of origin where developmental arrest has occurred at an earlier stage of in utero organogenesis.

In contrast, the other type of AVM, the truncular form, does not have a mesenchymal cell origin or characteristics. Both forms are classified based on the Hamburg classification (Table 42-1).

In addition to its unique embryological characteristics, AVM exhibits complicated hemodynamics. Both truncular and extratruncular AVM lesions are associated with altered cardiovascular hemodynamics occurring centrally, peripherally, and locally, involving the arterial, venous, and lymphatic systems. These characteristics make the AVM the most hemodynamically complex type of CVM. The AVM also carries a high rate of progression and significant destructive potential of the primary lesion and its secondary effects.⁴

The AVM, especially the infiltrating extratruncular-type lesion, is the most dangerous, primitive CVM that is associated with high rates of recurrence and potentially life-threatening and limb-threatening complications.

Proper treatment of AVMs requires accurate diagnosis and precise classification of its embryological subtype (as either truncular or extratruncular), and determination of its hemodynamic status.