To exclude other differential diagnoses, a skin biopsy may be taken. Imaging studies can be used in order to detect any underlying bony abnormalities that cause abnormal pressure on the overlying skin. For this purpose, a plain radiograph usually suffices, but, occasionally, CT scanning is used.
Corn 
Whitlow
Wellbee
Squawk 
Wart
Drustbed
Cowlick
Sniffle