Optical Coherence Tomography Visualization of a Port-Wine Stain in a Patient With Sturge–Weber Syndrome

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Excerpt

Optical coherence tomography (OCT) represents an innovative approach to the evaluation and management of port-wine stains (PWS) in patients with Sturge–Weber syndrome. Sturge–Weber syndrome is a congenital neurocutaneous disorder characterized by widespread vascular abnormalities including leptomeningeal angiomas and facial port-wine stains, particularly involving the ophthalmic distribution of the trigeminal nerve.1 Port-wine stains are capillary malformations that result from vascular ectasia because of retrograde venous pressure. An embryonic somatic activating mutation in GNAQ has been implicated in the pathogenesis, which dysregulates endothelin leading to focal vascular malformation.1 Histologically, PWS contain thin-walled vessels in the papillary and reticular dermis that spare the subcutaneous tissue.2 Unlike angiomas, PWS have no malignant potential and do not regress, though they can hypertrophy and darken with age.3 They are also prone to thrombosis as a result of reduced blood flow.
Optical coherence tomography is a noninvasive imaging device that can visualize tissue structures with a 2-mm penetration depth. A novel dynamic feature detects blood flow and provides the ability to view vessel architecture in vivo, enhancing the diagnostic value. This feature has yet to be used to evaluate PWS and represents a significant advancement in the capabilities of OCT imaging. Optical coherence tomography combines cross-sectional vertical images to create an en face view, with which the authors are able to determine the depth and characterize the vessel architecture in 3 dimensions (Michelson Diagnostics, Ltd., Kent, United Kingdom). Herein, the authors compare the OCT findings of PWS in a patient with Sturge–Weber syndrome to the unaffected skin in a healthy control. The institutional review board approval was obtained from the University of Miami before testing.
The PWS of a 30-year-old woman with Sturge–Weber syndrome and an age- and race-matched control patient with unaffected skin were scanned using OCT (6 × 6 mm, 120 frames). Cross-sectional images and en face images were analyzed and compared. The total blood flow was measured in each patient at incremental points in depth every 0.05 mm.
Optical coherence tomography findings in healthy skin and PWS are illustrated in Figures 1 and 2, respectively. The en face image of healthy skin has thin, 0.2-mm wide, linear blood vessels anastomosing at acute angles, forming a chicken wire pattern. The cross-sectional view has a smooth epidermal surface with a clearly defined linear dermal–epidermal junction overlying homogenously deposited dermal collagen. The PWS en face image has large, 0.4-mm wide, rounded, highly anastomotic vascular networks that are less organized. The cross-sectional image reveals beaded, snake-like, dilated vessels that closely abut the dermal–epidermal junction. The reflective material in the vessel lumen may represent a thrombus. The epidermal surface of the PWS is visibly less smooth than the control. Figure 3 graphically compares the overall blood flow of each scan at 0.05 mm increments in depth up to 0.5 mm, after which the dynamic signal detection begins to gradually decline. Measurable blood flow is detected in the PWS patient beginning at 0.1 mm, as opposed to 0.2 mm in the control patient. By 0.5 mm, blood flow is seen in nearly 20% of the pixels in the PWS scan compared with approximately 4% in the control patient.
Some of the findings echo those from previous studies, and the results add further means for PWS evaluation through the newfound utilization of the dynamic blood flow feature affording the authors the ability to view vessel architecture in vivo. Zhao and colleagues4 used OCT to examine epidermal thickness, diameter of blood vessels, and depth of blood vessels, which they found to be valuable objective traits in the examination of PWS.
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