solitary dark mole on back
This is a common presentation, someone notices a funny looking mole on their own or someone else’s back and suggests they get it checked. Seems reasonable, after all melanoma skin cancer is on the increase and it can kill you.
This person has a dozen or so small harmless looking ‘moles’ on their upper back, and one that sticks out like a sore thumb, or ugly duckling. Closer evaluation is required.
Mostly quite featureless. certainly no features such as reticular network or brown globules to make you think of a melanocytic lesion. There are several brownish clods of variable sizes-these are the comedo like openings of seborrhoiec keeratosis. How do we tell these from globules? Study hundreds of images-they are different.
Closer examination of the almost (but not quite ) featureless background reveals many small homogenous blood vessels. The pattern is small loops, typical of seborrhoeic keratosis. Which is the diagnosis. Other supporting features of seb k are the very well defined edge and fissures. an autocorrected image shows these fissures (circled) more readily. Click on the image to enlarge.
There is a blood vessel structure in the upper right quarter near the centre, the circle goes through it. This is just random. How can I say that with confidence? By studying many thousands of lesions. There are plenty of features here to support seb k, no features of skin cancer, and we simply do see varied random features in all kinds of skin lesions.
Many ugly ducklings are harmless, and can be proved so with the dermoscope, saving time, money and worry.