At a Glance - Blue naevus vs venous lake

Blue naevus

Blue naevus is smooth, slightly raised and appears blue

Presentation

  • Smooth, round, slightly raised, blue papules. Less than 0.5mm in diameter.
  • May occur anywhere on the body. Common on the face, and backs of hands and feet.
  • Dermoscopy - homogenous steely-blue colour. No network or other features.
  • Watch for sudden increase in size or ulceration.

Aetiology

  • Type of mole that forms when melanocytes collect in the mid- to lower dermis.
  • Due to its depth and the effect on preferential absorption of long wavelengths of light, the lesion appears blue.
  • Frequently present in the teens but may occur at any age. Usually persist throughout life.
  • More common in women and in Asian populations.
  • Benign lesions that rarely show malignant change.

Management

  • No treatment required unless for cosmetic reasons or concern of malignancy.
  • Surgical excision/biopsy.

Venous lake

Venous lake tends to occur in men over the age of 50

Presentation

  • Compressible, well-defined blue, red or purple papules with smooth surface.
  • Blanches on pressure.
  • Up to 1cm in diameter.
  • Usually symptomless but may sometimes bleed.
  • Dermoscopy - homogenous reddish-blue or reddish-black colour. No pigment structures.

Aetiology

  • Angioma due to dilated venules.
  • Tends to occur on lips or sun-damaged skin.
  • Usually present over the age of 50 and more common in men.

Management

  • No treatment necessary unless cosmetic, bleeding or diagnostic concerns.
  • Biopsy if in doubt about the diagnosis.
  • Surgical excision.
  • Cryotherapy, electrosurgery or sclerotherapy.
  • Laser therapy; argon laser and infra-red coagulator may result in scarring.

Contributed by Dr Jean Watkins, a sessional GP in Hampshire.

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