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Facts about the skin from DermNet New Zealand Trust. Topic index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


What are angiokeratomas?

Angiokeratomas are small dark red to purple raised spots. They may also have a rough scaly surface. They are composed of surface blood vessels (dilated capillaries). Often unnoticed, they may become crusty and bleed if accidentally scratched or damaged, or a harmless clot may form in the lesion (thrombosis), changing the colour to dark purple or black overnight.

There are several types of angiokeratomas:

What causes angiokeratomas and who gets them?

Apart from Fabry syndrome, which is caused by a genetic defect, the cause of other angiokeratomas is unknown.

Distinguishing features

Sporadic angiokeratoma
Scrotal angiokeratomas
Vulvar angiokeratomas
Angiokeratoma circumscriptum
Angiokeratoma circumscriptum
Type of angiokeratoma Description
Sporadic angiokeratoma
  • Solitary lesions
  • Common in those over 40 years
Angiokeratoma of Fordyce
  • Most commonly found on the scrotum. Also found on the shaft of the penis, labia majora of the vulva, inner thigh and lower abdomen
  • Most prevalent in those over 40 years
  • Men are more often affected than women
  • May be a single lesion or multiple lesions (>100)
  • Lesions are small, red and less scaly in younger patients whilst in older patients they tend to be larger, blue/black and with overlying scales
  • Usually symptomless and may only be noticed when they bleed after scratching or intercourse
Angiokeratoma circumscriptum
  • Rare birthmark (vascular malformation). May be present at birth but can occur later in childhood or adulthood
  • Females are more affected than men 3:1
  • Cluster of lesions on a small area of the leg or trunk
  • Over time lesions may darken in colour and change shape and size
Fabry syndrome (angiokeratoma corporis diffusum)
  • Rare serious inherited disorder caused by a deficiency of an alpha-galactosidase enzyme, ceramide trihexosidase
  • Excessive quantities of glycosphingolipids are deposited in blood vessels and internal organs
  • More severe in males than females
  • Angiokeratomas are widespread, most numerous on lower trunk and groin area
  • May present with fever and painful hands & feet
  • May result in corneal opacities, kidney failure, heart failure, strokes, arthritis, colitis & many other problems.

What is the treatment for angiokeratomas?

Angiokeratomas are harmless surface vascular lesions that can usually be left alone. As the black spots sometimes resemble melanoma, a skin biopsy may be performed to rule out malignancy and allay any fears.

If bleeding becomes a concern or treatment is requested for cosmetic purposes, they can be removed. Surgical options include excision, laser therapy, cryotherapy or electrocautery.

Related information


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Author: Vanessa Ngan, staff writer

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If you have any concerns with your skin or its treatment, see a dermatologist for advice.