View this YouTube video on Adnexal tumours and foreign bodies. Click on the arrow and when it starts go to the bottom of the screen and change the 360 resolution to 1080 and then click on the box with the arrows pointing out to enlarge to full screen. These videos are recorded in high definition which makes for great viewing if you have a fast broadband connection. Press ESC on your keyboard to return to normal size.
Most adnexal tumours are derived from hair follicles but others can come from eccrine sweat ducts or apocrine glands.
View this Pilomatrixoma case in Dermoscopy Atlas