Pimple On Cat's Ear. I was holding my cat Randy and noticed on the back of her ear there was a small bump. Scratching it or around it seems to relieve a sort of itch.

The medical term is ear edge dermatitis or ear margin dermatitis. Feline chin acne is a fairly common skin condition in cats and can be a one-time occurrence occasional flare or chronic issue. Known as pinnae the outer visible part of the cats ear is susceptible to developing thickening crusting and scaling.
I found it while scratching my cats head.
Squamous Cell Carcinoma SCC most commonly affects white noses eyelids and ears. It may just been a small cyst or maybe even a mole. Sebaceous cysts appear as raised bumps and are soft in feel. There is usually an underlying cause of a haematoma which requires treatment.