How quickly can seborrheic keratoses grow? If a skin lesion gets slightly larger within a short period of time, can it still be sk? What are causes?

Seborrheic keratoses. Seborrheic keratoses are benign skin lesions that are found in "older" individuals referred in layman's term as "barnacles", aging spots. You can get more as you get older. If a lesion gets bigger in a short period of time, be sure to check it out with a dermatologist to make sure that it is not an atypical mole or melanoma.
Fast. Nobody knows what causes them. If a huge crop appears at once, it can be a warning of internal malignancy and an indication for endoscopy. They can appear and grow very rapidly.