Concentric circles dermoscopy

What are concentric circles?

Concentric circles are a specific clue to melanoma on the face (lentigo maligna), but the clue has poor sensitivity as they are rarely present. In a study by Tschandl et al, concentric circles were only found in 4.2% of flat facial melanomas, usually larger lesions [1]. Concentric circles are also referred to as a circle within a circle and the isobar sign.

What do concentric circles look like through the dermatoscope?

Concentric circles consist of an asymmetrical pigmented follicular opening with a darker dot located within ostial openings.

Concentric circles (red arrows) seen in dermoscopy of pigmented actinic keratosis 

Concentric circles (red arrows) seen in dermoscopy of lentigo maligna 

Concentric circles (red arrows) seen in dermoscopy of lentigo maligna melanoma 

In which lesions are concentric circles seen in through the dermatoscope?

• Lentigo maligna
• Pigmented actinic keratosis (rarely).

Concentric circles seen in dermoscopy of a lentigo maligna. Courtesy of Prof Cliff Rosendahl 

Right post-auricular region 

 

 

 

Scalp