Concentric circles dermoscopy

Author: Naomi Ashman, Dermoscopist, Torbay Skin, Auckland, New Zealand; DermNet New Zealand Editor in Chief Adjunct A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Created January 2019.

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.

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

Lentigo maligna
Pigmented actinic keratosis (rarely).

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Related information

References

Dermatoscopy, Pattern analysis of pigmented and non-pigmented lesions by Harold Kittler, Cliff Rosendahl, Alan Cameron, Philip Tschandl; 2nd edition, 2016; Facultas Verlags- und Buchandels AG facultas Universitatsverlag, Vienna, Austria. Chapter 8, Special situations, P274.