The Wobble Sign

There is one more feature of seborrhoeic keratosis that does not involve structures or colours — it involves movement.

The wobble sign is observed when you apply gentle lateral pressure with the dermatoscope. Because seborrhoeic keratoses sit on top of the skin — superficially, in the epidermis — they can often be rocked or wobbled slightly when pushed from the side. The lesion moves as a unit, independent of the deeper skin layers.

This reflects the "stuck on" quality that clinicians describe when looking at seborrhoeic keratoses with the naked eye. Under the dermatoscope, you can feel and see this mobility directly.

How to test for it

While examining a lesion that you suspect is a seborrhoeic keratosis, apply gentle sideways pressure with the contact plate of your dermatoscope. If the lesion shifts or rocks slightly on the skin surface, that is a positive wobble sign.

The movement is subtle — a gentle rocking, not a dramatic shift. It works best with thicker, more raised lesions. Flat seborrhoeic keratoses may not wobble appreciably.

What the wobble sign tells you

A positive wobble sign is an additional piece of evidence supporting a superficial, epidermal lesion — consistent with seborrhoeic keratosis. It does not replace the structural features described above, but it complements them.

A deeper lesion — a dermal naevus, a nodular melanoma, a dermatofibroma — sits within or below the skin rather than on top of it. These lesions do not wobble in the same way.

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