Port-wine birthmark — Viva

Q1: Name and classify the lesion

Examiner: What is this lesion, and where does it sit in current ISSVA terminology? [3]

Model answer: This is a port-wine birthmark (PWB; port-wine stain; naevus flammeus). It is a congenital capillary malformation, a simple slow-flow vascular malformation, not a vascular tumour. It is present at birth, grows with the child, persists, and may darken or thicken. [3][15]

Examiner: What wording would lose marks? [3][13]

Model answer: Calling it a haemangioma, saying it proliferates and involutes, or describing it as an acquired “stain.” The familiar name remains acceptable, but “port-wine birthmark / capillary malformation” states the biology more accurately. [3][13]

Q2: Explain the molecular basis without overstating it

Examiner: What is the genetic basis? [5][6]

Model answer: A postzygotic activating mosaic GNAQ variant, usually p.R183Q, is the landmark and common finding in isolated PWB and SWS tissue. It is not universal; GNA11-associated capillary-malformation phenotypes and wider genetic heterogeneity are reported. The lesion is usually sporadic, and a blood test may be negative because the variant is tissue mosaic. [5][6]

Examiner: Take me from GNAQ to vascular ectasia. [5][6]

Model answer: I would not recite a definitive PLC-beta/IP3/DAG/calcium cascade as proven causation. MAPK/ERK and other pathways are implicated, but the causal cell and the complete route to persistent ectatic dermal vessels remain incompletely resolved. Reduced vascular innervation is a proposed contributor, not a universal mechanism. [5][6]

Q3: Map the facial risk correctly

Examiner: Is this a V1 port-wine stain? [14]

Model answer: Trigeminal labels are anatomically memorable but clinically inferior for SWS risk. I map the forehead territory, defined by the vascular-territory work rather than a sensory dermatome. Forehead involvement predicts brain risk; I do not reassure from a “V2/V3 only means zero” rule. [14][15]

Examiner: What does the eyelid add? [12][15]

Model answer: Any upper- or lower-eyelid/periocular involvement predicts glaucoma risk. The infant needs prompt paediatric ophthalmology assessment with intraocular pressure and complete ocular examination, followed by lifelong individualized surveillance because glaucoma can present in infancy or later. [12][15]

Examiner: What are your referrals today? [12]

Model answer: Baseline paediatric neurology for the forehead brain-risk phenotype and prompt paediatric ophthalmology for eyelid involvement. I give a family safety-net for seizures, focal deficits, stroke-like episodes, developmental regression, photophobia, tearing, corneal clouding, and apparent eye enlargement. [12]

Q4: Defend your MRI plan

Examiner: The infant is well. Do you order contrast MRI today? [12]

Model answer: Not automatically. Consensus does not recommend routine screening MRI for every asymptomatic high-risk infant. Neurology discusses selective imaging, particularly for extensive or bilateral lesions, subtle symptoms, or when presymptomatic treatment is contemplated. [12]

Examiner: If the family wants reassurance from a normal neonatal MRI, what do you say? [12]

Model answer: An early MRI may be falsely negative, so a normal scan does not exclude SWS. Neurology follow-up and the seizure/developmental safety-net continue. This is why “V1 mandates neonatal MRI” is both outdated and potentially falsely reassuring. [12][14]

Examiner: When does imaging become urgent? [12]

Model answer: With a first seizure, focal deficit, stroke-like episode, or developmental regression. The symptomatic child needs urgent neurology assessment and an optimized MRI protocol with appropriate pre- and post-contrast sequences rather than a limited screening study. [12]

Q5: Work through the differential

Examiner: The parent says a sibling had a birthmark that faded. What is the main alternative? [3][15]

Model answer: Naevus simplex. It is often central or symmetric at the glabella, eyelids, or nape and usually fades, although nuchal lesions may persist. Blanching overlaps with PWB and is not an absolute discriminator. [3][15]

Examiner: Can a lesion seen at birth be an infantile haemangioma? [15]

Model answer: A subtle infantile-haemangioma precursor can be visible at birth. The differentiating course is early proliferation followed by involution, whereas a PWB grows with the child and does not involute. “Present at birth means it cannot be haemangioma” is too absolute. [15]

Examiner: What bedside finding changes this from slow-flow to fast-flow disease? [7][15]

Model answer: Warmth, pulsation, thrill, or bruit. In a limb with overgrowth, slow-flow capillary-lymphatic-venous disease suggests KTS; a thrill or bruit suggests fast-flow Parkes Weber syndrome and prompts targeted shunt imaging. [7][15]

Q6: Counsel and plan laser treatment

Examiner: What is first-line treatment? [13]

Model answer: Pulsed dye laser, if the patient or family wants treatment. It selectively targets oxyhaemoglobin and can provide meaningful lightening. Earlier treatment may help, but I do not promise a universal starting age, fixed course, or complete clearance. [13]

Examiner: Give me the standard fluence, spot size, pulse duration, interval, and session number. [13]

Model answer: There is no universal recipe. The experienced operator individualizes wavelength, fluence, spot, pulse, overlap, epidermal cooling, and endpoint to lesion site, depth, colour, phototype, device, and prior response. Session interval and number are also individualized; multiple sessions and later touch-ups are common. [13]

Examiner: What adverse effects and safeguards do you discuss? [9][13]

Model answer: Expected pain, oedema, and purpura or colour change; possible dyspigmentation, blistering, textural change, and rare scarring. Use cooling, cautious overlap, and phototype-aware settings. For treatment within the orbital rim, use properly fitted corneo-scleral shields placed and monitored by a trained clinician; outside the orbital rim, use laser-wavelength-specific external eye shields. Darker phototypes have a narrower therapeutic window and greater pigmentary risk. [9][13]

Examiner: Must this infant receive general anaesthesia? [13]

Model answer: No. Analgesia and movement control depend on age, extent and site, pain, eye safety, previous experience, child/family preference, and local expertise. Small or moderate lesions may be treated without general anaesthesia; extensive or safety-critical procedures may justify it after shared decision-making with paediatric anaesthesia. [13]

Q7: Syndromes, prognosis, and counselling

Examiner: State the Sturge-Weber triad. [5][12]

Model answer: Historically: facial PWB, leptomeningeal vascular malformation, and glaucoma. The higher-level answer is that SWS can be partial; a complete triad is not required for diagnosis or referral. Brain and eye involvement vary. [5][12]

Examiner: Contrast KTS and Parkes Weber syndrome. [7][15]

Model answer: KTS is a slow-flow capillary-lymphatic-venous malformation with limb overgrowth, commonly PIK3CA mosaic. Parkes Weber is fast-flow with arteriovenous fistulae; warmth, thrill, or bruit are key clues. I would not describe AV shunts as a routine KTS component. [7][15]

Examiner: What do you tell the parents about inheritance and prognosis? [6][13]

Model answer: PWB is usually sporadic and tissue mosaic, so sibling and offspring recurrence is expected to be low but should not be promised as exactly zero. The skin lesion persists and may darken or thicken. PDL can lighten it, but response varies, complete clearance is uncommon, and touch-ups may be needed. Their informed choice can include laser, camouflage, visible-difference support, or no active treatment. [6][13]

Examiner Closing Checklist

A pass requires the candidate to: [12][13]

1. call PWB a capillary malformation, not a haemangioma;
2. replace trigeminal-dermatome risk with forehead and eyelid phenotypes;
3. separate neurology, ophthalmology, and selective MRI decisions;
4. state that early MRI may be falsely negative;
5. avoid a fixed PDL recipe and protect the eye;
6. individualize analgesia and general anaesthesia;
7. distinguish slow-flow KTS from fast-flow Parkes Weber;
8. preserve uncertainty around mosaic genetics, mechanism, clearance, and recurrence. [6][7][12][13][14]