Medical Mystery of the Week

You are sent a picture of this patient's back (see image below) and told that the lesions appeared suddenly over a period of 2-3 weeks. What is your diagnosis, what test(s) would you order to confirm your suspicions, and what treatment, if any, do you recommend?

DIAGNOSIS: Multiple seborrheic keratosis, a common finding, particularly as we age.

However, the sudden appearance of these lesions over several weeks or months should raise one's suspicions of an underlying malignancy and prompt a thorough search. In this circumstance, the appearance of the keratoses is referred to as the sign of Leser Trelat.