Many seborrheic keratoses on the back of a person with<unk>  due to colon cancer The<unk>  is the explosive onset of multiple seborrheic keratoses (many pigmented skin lesions), often with an inflammatory base. This can be a sign of internal malignancy as part of a paraneoplastic syndrome. In addition to the development of new lesions, preexisting ones frequently increase in size and become symptomatic.
Leser–Trélat sign
Asboe-Hansen sign
De Musset's sign
Destot's sign
Amsler sign
Auspitz's sign
Froment's sign
Hegar's sign