Nevus flameus
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"nevus flammeus" OR "port wine stain"
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Nevus Flammeus (Port-Wine Stain / Capillary Malformation)
Terminology
Nevus flammeus (Latin: "flame nevus") is the classical name for what is now formally classified as a capillary malformation (CM) - a slow-flow vascular malformation of the skin. Common synonyms include port-wine stain (PWS) or port-wine birthmark (the currently preferred term by the ISSVA). Note that "nevus flammeus neonatorum" (also called nevus simplex, salmon patch, stork bite, or angel's kiss) is a separate, benign transient entity that must not be confused with true CM.
Epidemiology
- Prevalence: ~0.3% of the population
- No sex preponderance
- Most cases are sporadic (somatic mutation), but inherited (autosomal dominant, multiple) forms exist as part of the CM-AVM syndrome
(Fitzpatrick's Dermatology, p. 2668)
Clinical Features
Nevus Flammeus Neonatorum (Figure A below - the transient neonatal variant):
Figure: (A) Facial nevus flammeus neonatorum. (B) Unna nevus on the nape of the neck - both are transient variants. - Fitzpatrick's Dermatology
True Capillary Malformation (Port-Wine Stain):
Figure: (A) Extensive right facial CM involving V1/V2 trigeminal branches in Sturge-Weber syndrome. (B) Choroidal CM with glaucoma. - Fitzpatrick's Dermatology
| Feature | Description |
|---|---|
| Appearance | Red-to-deep purple, flat, homogenous, geographic or dermatomal |
| Onset | Congenital, present at birth |
| Location | 50% on face (trigeminal distribution: V1, V2, V3); also extremities, trunk |
| Laterality | Often unilateral |
| Temperature | Normal (cold; never warm - distinguishes from AVM) |
| Blanching | Does NOT blanch completely |
| Pain/bleeding | Flat and painless; no spontaneous bleeding |
| Course | Persists lifelong and progressively darkens to purple; soft tissue hypertrophy develops over time |
(Fitzpatrick's Dermatology, p. 2669; Kanski's Clinical Ophthalmology, p. 63)
The palate/oral mucosa can also be involved, as seen here:
Figure: Mucosal port-wine stain of the palate - Andrews' Diseases of the Skin
Pathogenesis & Genetics
- Sporadic CM: caused by somatic activating mutations in GNAQ (a G-protein alpha subunit mediating signals between G-protein-coupled receptors and downstream effectors). The same mutations drive Sturge-Weber syndrome (SWS).
- Clonal expansion of abnormal neural-crest-derived cells is the proposed mechanism for facial CM.
- Phakomatosis pigmentovascularis (PPV): mutations in GNAQ or GNA11 lead to combined CM + pigmented nevus.
- Inherited CM-AVM1: inactivating mutations in RASA1 (GTPase-activating protein, negatively regulates Ras).
- Inherited CM-AVM2: inactivating mutations in EPHB4 (regulates arteriovenous identity, interacts with RASA1 via RAS-MAPK signaling).
- M-CM (Macrocephaly-CM): activating mutations in AKT3, PIK3CA, PIK3R2.
(Fitzpatrick's Dermatology, p. 2671)
Histology
- Dilated capillaries of the papillary and upper reticular dermis
- Areas of increased number of otherwise normal-appearing capillaries
- Endothelial cells are flat
- Factor VIII, fibronectin, and basement membrane proteins are normal
- S100 staining shows abnormal innervation (key finding)
- Immunohistochemistry: D2-40 negative (distinguishes from lymphatic malformation)
(Fitzpatrick's Dermatology, p. 2671; Kanski's Clinical Ophthalmology)
Complications
- Soft tissue hypertrophy - especially V2/V3 dermatomes; affects lips, gums, maxilla/mandible - leading to skeletal asymmetry, occlusal tilt, open-bite deformity
- Pyogenic granulomas - lobular vascular overgrowths that can bleed; arise within the PWS especially during adolescence
- Purple nodules and verrucous/cobblestone thickening of the skin over time
- Meyerson phenomenon - atopic dermatitis, psoriasis, or acne is worse within the CM area
- Ocular - glaucoma, episcleral hemangioma, choroidal hemangioma (in SWS)
- Leg-length discrepancy when extremities involved
(Fitzpatrick's Dermatology, p. 2671)
Associated Syndromes
| Syndrome | Key Features |
|---|---|
| Sturge-Weber Syndrome (SWS) | Facial CM (V1 ± V2/V3) + ipsilateral leptomeningeal angioma (seizures, hemiparesis, hemianopia) + ipsilateral glaucoma |
| Klippel-Trenaunay Syndrome | CM + varicosities + limb hypertrophy |
| Proteus Syndrome | CM + hemihypertrophy + macrodactyly + epidermal nevus + cerebriform plantar overgrowth |
| Phakomatosis Pigmentovascularis | CM + pigmented nevus (nevus spilus, Ota) ± systemic involvement |
| CM-AVM Syndrome | Multiple atypical CMs + AVMs (RASA1/EPHB4 mutations) |
| Macrocephaly-CM (M-CM) | CM + macrocephaly (PIK3CA, AKT3) |
| TAR Syndrome | Thrombocytopenia + absent radius + occasionally PWS |
Differential Diagnosis
| Condition | Distinguishing Features |
|---|---|
| Nevus flammeus neonatorum (salmon patch) | Median location (glabella, nape, eyelids), fades by 1-4 years |
| Infantile hemangioma | Appears weeks after birth, raised, grows rapidly then involutes |
| Telangiectasia | Fine red vessels, not a solid patch |
| CMTC (Cutis Marmorata Telangiectatica Congenita) | Marbled blue-red pattern, often with skin atrophy |
| CM-AVM | Multiple, smaller, atypical CMs; inherited |
Diagnosis
- Clinical diagnosis in most cases
- Doppler ultrasound is indicated only if the lesion is painful, warm, or spontaneously bleeds (to rule out fast-flow AVM)
- MRI/MRA when SWS or intracranial involvement is suspected
- Ophthalmologic evaluation starting in infancy for lesions involving V1 territory (glaucoma screening)
(Fitzpatrick's Dermatology, p. 2671)
Treatment
First-Line: Pulsed-Dye Laser (PDL)
- Wavelength: 585 nm or 595 nm; short pulse duration (400-1500 ms)
- Gold standard - targets oxyhemoglobin selectively (selective photothermolysis)
- 6-12 sessions typically required; general anesthesia may be needed in children
- Dynamic cooling device used to protect epidermis and allow higher fluence
- More effective on face/cervical/trunk lesions than extremities
- Does not improve associated soft tissue hypertrophy
- Recurrence can occur after stopping treatment
A recent systematic review and network meta-analysis (Nguyen et al., 2025) confirmed PDL at 595 nm remains the best-evidence treatment for port-wine birthmarks.
Other Modalities
- Topical rapamycin (sirolimus) - alone or as adjuvant to laser, shows promise
- Topical imiquimod - adjuvant role
- Contour resection / soft tissue debulking - for hypertrophy complications (lip, gum overgrowth)
- Camouflage makeup - highly effective noninvasive option for cosmetic management
- Orthopedic - shoe lifts for leg-length discrepancy >1.5 cm; epiphysiodesis at ages 11-13
For SWS specifically
- Prompt ophthalmologic follow-up from birth (glaucoma management)
- Prophylactic antiepileptic therapy - advocated but lacking robust RCT evidence
- Neuroimaging for leptomeningeal involvement
(Fitzpatrick's Dermatology, p. 2673-2674; Kanski's Clinical Ophthalmology, p. 63-64)
Key Points Summary
- Nevus flammeus = capillary malformation (CM) = port-wine stain - a congenital, slow-flow vascular malformation
- Caused by somatic GNAQ mutation; presents at birth, never involutes
- Darkens with age; soft tissue hypertrophy develops over decades
- 50% facial (trigeminal distribution); always assess for Sturge-Weber syndrome when V1 is involved
- Histology: dilated capillaries in upper dermis, S100-negative innervation, D2-40 negative
- Gold-standard treatment: pulsed-dye laser (595 nm) - multiple sessions required
- Distinguished from "nevus flammeus neonatorum" (salmon patch) which is transient and benign
Sources: Fitzpatrick's Dermatology (Vol. 1-2), Kanski's Clinical Ophthalmology (10th ed.), Andrews' Diseases of the Skin; supplemented by Nguyen et al. 2025 network meta-analysis and Hashemi et al. 2025 systematic review on laser treatment.
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