Dermoscopy of Seborrhoeic Keratosis

Question 1

What is the ‘Wobble Sign’?

Answer 1

The ‘wobble sign’ may be useful to distinguish a papillomatous melanocytic naevus from a stable seborrhoeic keratosis.

Question 2

What 4 melanocytic lesions can be confused with Seborrhoeic Keratosis?

Answer 2

Dermal naevi, Congenital naevi, Spitz naevi and Nodular melanoma, can be confused with Seb K as they may have similar features

Question 3

What are 6 dermoscopic features of Seborrhoeic Keratosis?

Answer 3

1-Milia-like cysts – two types:

a) Tiny white starry
b) Larger yellowish cloudy

2-Irregular crypts

3-Fissures/ridges

4-Blue-grey globules

5-Light brown fingerprint-like parallel structures

6-‘Fat fingers’ (the gyri of a cerebriform surface)

Question 4

How do Seborrhoeic Keratosis demonstrate chaos and clues in the ‘Chaos and Clues method’, and what are some clinical clues to Seborrhoeic Keratosis?

Answer 4

• Seb K’s demonstrate Chaos via modified pattern analysis i.e they often have asymmetry of colour and structure on dermascopy.
• Seb K’s demonstrate Clues via modified pattern analyses e.g.
• Multiple orange clods
• Multiple white clods
• Thick curved lines
• Sharply demarcated border over total periphery
• Clinical clues to Seborrhoeic Keratosis are:
• Multiple grouped similar lesions
• Stuck-on lesion
• Waxy or scaly surface