Spider Naevus

Acquired vascular lesion made of a central ascending arteriole (the "body") with radiating thin walled capillary branches (the "legs"). It is also called spider naevus or naevus araneus.

• Common and usually benign. About 10 to 15% of healthy adults have at least one, and about 10 to 20% of healthy children (peak 2 to 15 years, often on the face or dorsum of the hand). It is found in 30 to 60% of pregnant women, appearing from the second to fifth month and often regressing within 3 months after delivery.
• Oestrogen drives their appearance. Multiple lesions occur with pregnancy, oestrogen containing contraceptives, hormone therapy and, importantly, chronic liver disease (alcoholic or viral cirrhosis), where raised oestradiol relative to androgen and altered hepatic clearance are responsible.
• A lesion count of 5 or more, or sudden eruption of many lesions in an adult who is not pregnant and not on oestrogen, should prompt a liver assessment. They are also seen in thyrotoxicosis, severe malnutrition and rarely in hereditary haemorrhagic telangiectasia (which has a different structure).
• Lesions stay in the vascular territory of the superior vena cava: the face, neck, upper chest, shoulders, arms and dorsum of the hands. Lesions below the umbilicus are rare.

• A central red or violet punctum, 1 to 2 mm, sometimes slightly raised and pulsatile, with radiating fine red vessels extending 1 to 15 mm. Pressure on the central arteriole blanches the whole lesion, and the legs refill from the centre outward when pressure is released (a key distinguishing sign).
• Usually asymptomatic. Occasional bleeding with trauma, and cosmetic concern.
• In liver disease the lesions are larger, more numerous and accompanied by palmar erythema, gynaecomastia, testicular atrophy, jaundice, ascites, caput medusae or hepatomegaly.
• Differential diagnosis: cherry angioma (no radiating legs, does not blanch from the centre), telangiectasia (no central feeding vessel), venous lake, petechiae (do not blanch), hereditary haemorrhagic telangiectasia (lips, tongue, fingertips, nose bleeds, family history), pyogenic granuloma, Campbell de Morgan spots, angioma serpiginosum, and basal cell carcinoma (telangiectatic).
• Complications: bleeding after trauma, recurrence after removal if the central vessel is not destroyed, and in liver disease the complications of the underlying condition.

• Clinical, using the pressure test: pressing the centre with the tip of a pen or glass slide blanches the lesion completely.
• Dermoscopy shows a central red globule with radiating vessels.
• In adults who are not pregnant and not on oestrogen, with multiple lesions or other stigmata, check liver tests (ALT, AST, bilirubin, albumin, INR), full blood count with platelets, hepatitis B and C serology, ferritin and transferrin saturation, autoimmune markers, and arrange liver ultrasound with elastography. Ask about alcohol intake in detail.
• Check thyroid function if thyrotoxic features exist.
• In children, a solitary lesion needs no tests. Many lesions in a child, or with systemic features, warrant a full blood count and liver tests.
• Biopsy is not required unless the diagnosis is doubtful.

• No treatment is needed. Reassure the patient. Lesions in pregnancy usually fade within 3 months after delivery, and in children about three quarters resolve spontaneously, so defer treatment in these groups.
• Cosmetic treatment (the aim is to destroy the central arteriole):
  • Pulsed dye laser 585 to 595 nm, 1 to 2 sessions at 4 to 6 week intervals, with a spot size of 5 to 7 mm and the lowest fluence that causes transient purpura. It is the preferred treatment for facial lesions because scarring is least likely. Purpura fades in 7 to 14 days.
  • Potassium titanyl phosphate (532 nm) or long pulsed Nd:YAG laser for larger or deeper central vessels.
  • Electrodesiccation or fine needle electrocautery: after lidocaine 1% 0.1 to 0.2 mL if wanted, insert a fine epilation needle into the central punctum and apply a very short, low energy pulse until the lesion blanches. Do not treat the radiating legs separately. It is fast and cheap, with a small risk of a pitted scar or pigment change.
  • Cryotherapy with liquid nitrogen for 3 to 5 seconds on the centre, with a risk of hypopigmentation in dark skin.
  • Intense pulsed light for numerous small lesions.
• Bleeding: apply direct pressure for 10 minutes, then aluminium chloride 20% solution or a silver nitrate stick.
• Aftercare: petroleum jelly and a non-stick dressing for 3 to 7 days, sun protection of SPF 30 or more for 4 to 6 weeks, and avoid picking the crust.
• Liver disease: treat the cause, which is the only way to reduce new lesions. Alcohol cessation, antiviral therapy for hepatitis B (entecavir 0.5 mg daily or tenofovir 245 mg daily) or hepatitis C (direct acting antivirals under hepatology), and management of cirrhosis complications. Lesions may regress with improved liver function but often persist.
• Special groups:
  • Pregnancy: defer treatment until at least 3 months after delivery. Laser and cryotherapy are acceptable if the patient insists.
  • Children: observe for 1 to 2 years before treating, since most resolve. Use pulsed dye laser if needed.
  • Dark skin: use conservative laser settings, avoid cryotherapy where possible, and test a small area first.
  • Anticoagulation: laser or cryotherapy is safer than electrodesiccation, with pressure for bleeding.
  • Oestrogen containing medicines: if multiple lesions are troublesome, discuss a non-oestrogen alternative.
• Follow up: none for isolated lesions. Review at 6 to 8 weeks after treatment to check clearance, with repeat treatment if the centre persists. Refer to hepatology for any suspected liver disease, and to dermatology for resistant lesions or diagnostic doubt.