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Solar Lentigo

Author: Dr Amy Prideaux 

Chief Editor: Dr Daniel Keith

Macroscopic Appearance

A solar lentigo is a harmless flat spot of darkened skin which results from exposure to UV radiation causing a local proliferation of melanocytes. They tend to appear on the face, neck, shoulders and forearms but can occur anywhere on the body (you may haven seen them on the back of hands, sometimes referred to as age spots).

 

Compared to a freckle, solar lentigos tend to be darker in colour, larger in size, and do not fade in winter months.

 

They are essentially flat seborrheic keratosis. These seborrheic keratosis can arise within solar lentigos and if this happens the lesion would change in texture, and become thicker.

​Features: 

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  • Tanned brown colour

  • Well defined borders

  • Flat

  • Regular or irregular in shape

  • May have a slight overlying scale

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Macroscopic appearance of a single solar lentigo which appears irregular in shape, with a uniform tanned brown colour.

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Multiple solar lentigos can be seen on this patient's forehead. As you can see they can be variable in shape (including circular spots, larger ovals, and irregularly shaped structures) and size (ranging from a 1-2mm to 1-2cm).

Dermoscopic Appearance

The following features may be helpful when considering whether a lesion is a solar lengigo or not. These will be further explained in the images below.

 

  • Moth eaten border

  • Structureless light brown pigment

  • Small circles

  • Perifollicular brown, round pigmentation

  • Finger printing pattern

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Moth eaten border

  • Sharply defined in-pouchings in the structure giving the appearance of an irregularly curved border

 

Structureless light brown pigment

  • Bland looking, featureless brown colour

  • Lack of a pigment network or structures

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Perifollicular brown, round pigmentation

  • Isolated, darker brown circles surrounding a pale centre

  • Larger than small circles

 

Finger printing pattern

  • Fine parallel lines resembling that of a finger print

  • This can also look a little bit like the surface of wood Brown in colour

 

Small circles

  • Small touching circles with a pigmented border and pale centre

  • This can often resemble frogspawn

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